elements 21, Issue 4 | 2007 - corporate.evonik.com

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elements21S C I E N C E N E W S L E T T E R | 1 8 | 1 9 | 2 0 | | 2 0 0 7

Coating & Bonding TechnologiesDesigning with PolymersBiotechnologyInterfacial TechnologiesInorganic Particle Design

S C I E N T I F I C F O R U M

Evonik Meets Science

“The future begins here,” pledged Creavis employees and visitors at the inauguration of the NanotronicsScience-to-Business Center almost two years ago in Marl. It was written in red letters on the floor to theoffices and pilot plants and underscored how highly we value research. For one Creavis project, the futurehas indeed begun. That project is the flexible ceramic separator SEPARION®, which enables the use oflarge-scale lithium-ion batteries. For this development, Evonik Industries and Prof. Paul Roth of the Univer-sity of Duisburg-Essen have been nominated for the Federal President’s Future Prize 2007. The nomina-tion honors both the scientific quality of the work, as well as the overall importance of the innovation tosociety, where it will create new long-term jobs. We are quite proud of this achievement.

One of the factors in the success of this development has been close contact among the scientists, bothinternally and externally: The best ideas occur in direct dialogue, and short communication paths ensurethat they are not lost. This is also the motivation for our Evonik Meets Science event. Continuing the tradi-tion developed at Degussa, we extended our fourth-ever invitation to some 200 scientists to join us to dis-cuss current research topics, inspire new ideas, and gather feedback.

This issue will give you a look at the topics we addressed – topics as diverse in their content as they arein their stages of development: Some are still at the level of basic research, while others have already reached market maturity. We need both kinds – those that are in their infancy, and those that are appli-cation-oriented. The Nobel Prizes for the year 2007 in Physics and Chemistry provide impressive proof ofthis. While Peter Grünberg tracked an exotic phenomenon of sold-state physics and, in the process, made adiscovery that revolutionized storage technology, Gerhard Ertl worked on an application-relevant issue:How metal surfaces enabled certain chemical reactions. His methods, however, came from basic research.

Utilizing the strengths of university and industrial research alike, close contact among scientists, beingopen to new ideas – this describes our innovation philosophy. The Areas of Competence, the Science-to-Business Center, and Evonik Meets Science reflect this mindset. If you would like to learn more about theindividual projects we discussed during the event, please do not hesitate to use the phone numbers and call the authors. Research requires dialogue.

I hope you enjoy reading the current issue.

2 elements21 E V O N I K S C I E N C E N E W S L E T T E R

E D I T O R I A L

Research Requires Dialogue

BIOTECHNOLOGY26 Tissue engineering: Conquering new territory

with artificial organs29 From extraction to fermentation:

New business prospects for specialty amino acids

NEWS30 Groundbreaking ceremony:

New production plant for methacrylates in Shanghai 30 PMMA molding compounds for flat panel displays:

New plant comes onstream in Taiwan31 Evonik and TSM plan construction of an

integrated solar silicon production facility 31 R&D center expanded in Shanghai

INTERFACIAL TECHNOLOGIES32 Nanoemulsions for PEG-free cosmetics by

simple dilution with water

35 Water makes the diesel clean: Microemulsions reduce the discharge of pollutants from engines

INORGANIC PARTICLE DESIGN38 Evonik is the leading producer of inorganic particles:

Nearly endless applications41 Inorganic nanofillers for transparent polymers:

Invisible helpers for new functionalities

44 EVENTS AND CREDITS

elements21 | 2007

The cover picturesymbolizes Evonik’sfive Areas of Compe-tence, which were also the topics atEvonik Meets Science (see p. 8)

4 FUTURE PRIZECeramic separator for lithium-ion batteries:Evonik team nominated for the german future prize

8 EVONIK MEETS SCIENCE SCIENTIFIC FORUMIntense dialogue between science and industry

COATING & BONDING TECHNOLOGIES10 Highly reactive powder coatings expand the range of

applications: Breakthrough in storage stability thanks to purified formulation

13 Automotive coatings – the silent revolution:Although automotive coatings are already high in quality, research continues at breakneck speed

DESIGNING WITH POLYMERS16 New functions by programmed self-assembly:

Macromolecular building blocks made from polymer-peptide conjugates

19 Drug delivery systems: Conveying active ingredients to the cell interior

NEWS23 Evonik Röhm: 100 years of thefuture24 Creavis’ nanotronics summer school

links science and industry24 Threonine facility being expanded in hungary25 Catalysis research: Evonik employees

receive renowned raney award

Dr. Alfred OberholzMember of the Executive Board ofEvonik Industries AG

contents

elements21 E V O N I K S C I E N C E N E W S L E T T E R 3

news

European researchers interested in putting their exceptional scientificwork in biotechnology into practice can look forward to support fromEvonik Industries. For the second time, the company is offering theEuropean Science-to-Business Award, an innovation award that rec-ognizes the market potential of an invention and assists its conversionto innovation. The award carries a prize money of € 100,000 and alsoincludes management training at the University of St. Gallen.

“Our objective in offering the award is to build bridges betweenuniversity and industrial research,” said Dr. Alfred Oberholz, the mem-ber of the Executive Board of Evonik Industries AG with responsibili-ty for R&D in the Chemicals Business Area. “We want to motivateyoung scientific talent with an entrepreneurial spirit and help themswiftly convert their research results into products.” The European Sci-ence-to-Business Award 2008 is aimed at scientists, entrepreneurs,and the founders of start-ups who research or work in the field ofwhite biotechnology, are 38 years old or younger, and work in a teamwith a maximum of three members. Entries must be received byMarch 31, 2008.

Before the winner of the Evonik European Science-to-BusinessAward in white biotechnology is announced in the fall of 2008, theentries will be thoroughly examined by a renowned jury from industryand science. In addition to Evonik Executive Board member Dr. AlfredOberholz, the members of the jury include Wim Soetaert, professor ofbiochemical technology at the University of Gent; Philippe Soucaille

of the French company Metabolic Explorer; Prof. Heinz Saedler, direc-tor of plant breeding research at the Max Planck Institute in Cologne;Prof. Thomas Gutzwiller of the school for entrepreneurs at the Uni-versity of St. Gallen; and Steffen Klusmann, editor-in-chief of Finan-cial Times Germany, which supports the Award as a media partner.Dr. Arend Oetker, president of the Donor’s Association for the Promo-tion of Sciences and Humanities in Germany, is patron of the Award.

“This time, we decided that the focus would be on white biotech-nology, because its environmental and economic advantages are in-creasingly making it one of the key technologies of the 21st century,”explained Oberholz. Experts predict that as early as 2010, between10 and 20 percent of all chemical substances will be produced by bio-technological means. In specialty chemicals, which represents 40 per-cent of the chemical industry and is therefore its largest single sector,growth is projected to increase significantly over the same period.

In 2006, Russell Cowburn, professor of nanotechnology atImperial College, London, accepted the first European Science-to-Business Award in the field of material sciences: “The Award helpedme enormously in developing and implementing my ideas for themanufacture of magnetic data storage,” he said. He also has a tip forthe Award winner in 2008: The prizewinner should just get used tohis newfound popularity and practice giving speeches.

More information on the Evonik European Science-to-BusinessAward can be found at www.evonik.com/award.

Evonik was christened in a spectacu-lar event on September 12 in Essen.Evonik Industries AG is the creativeindustrial group which operates inthree highly profitable, promisingbusiness areas: Chemicals, Energy,and Real Estate. The company is aglobal leader in specialty chemicals,an expert in power generation fromhard coal and renewable energies,and one of the largest private resi-dential real estate companies inGermany. Evonik Industries is activein over 100 countries around theworld. In fiscal 2006 around 43,000employees generated sales of €14.8billion and operating profit (EBIT) ofover €1.2 billion. Evonik plans toenter the capital market in the firsthalf of 2008

+++ White Biotechnology: Evonik Industries Offers European Science-to-Business Award

+++ Evonik. Power to create.


C E R A M I C S E P A R AT O R F O R L I T H I U M - I O N B AT T E R I E S

r. Andreas Gutsch and Dr. Gerhard Hörpel of EvonikIndustries, along with Prof. Paul Roth of the Univer-sity of Duisburg-Essen, are among the nominees forthe German Future Prize 2007. The team impressed

the judges with its entry Nanoschicht mit Megaleistung(“Nanolayer with Megapower”), an application that enables thesafer use of large-scale batteries, and opens up new opportuni-ties for the consumption of sustainable energy sources.

Endowed with € 250,000, the German Future Prize of theFederal President is one of the most prestigious science andinnovation awards in Germany: To be nominated, inventionsmust not only be considered pathbreaking, but must also havebeen developed to market maturity and contribute to job crea-tion. The most recent validation for the reputation of the Prize:Prof. Peter Grünberg, Physics Nobel Prize recipient, had alsoreceived the German Future Prize in 1998. “We are very happyto have been nominated. It reflects the revolutionary break-through in the field of lithium-ion batteries and, at the sametime, is an indication of the outstanding creative potential with-in the Evonik Group,” said Dr. Werner Müller, CEO of EvonikIndustries AG. “In Kamenz, near Dresden, we are now com-mencing serial production of battery components,” Müller con-tinued.

Lithium-ion batteries are considered the most promisingcandidates for the mobile energy supply of the future. They arelighter, smaller, and more powerful than the other competitivetechnologies: lead acid and nickel-cadmium batteries. Theyhave an exceptionally high energy and performance density, arelatively high cell voltage of 3.6 volts, and also have a longeruseful life. This is why almost all of today’s cell phones, notebookcomputers, and camcorders operate on lithium-ion batteries.

Evonik Team Nominated for the

D Ceramic separators from Evonik enable the use of large lithium-ion batteries

Other areas of application in which there is a demand for large-scale batteries, however, have been barred to lithium-ion bat-teries, because they could not meet the safety requirements.One of their weaknesses was in the battery separator. Conven-tional separators, semipermeable polymer membranes used toseparate the anode and the cathode in the battery, have two keydisadvantages: They are flammable and lose their stability attemperatures above 140 °C (284 °F). This means that if batteriesequipped with these separators are overloaded, they can over-heat, melt, and trigger a short circuit.

The innovation nominated for the Future Prize, which isbased on a joint project among the German Research Founda-tion, Evonik Industries, and seven universities, provides a remedy:A new kind of separator, which Evonik Industries is marketingunder the name SEPARION®. SEPARION® is made of ceramicand polymers – two materials that are incompatible, given theirdiffering temperature requirements. The combination of low-temperature sintering and high-temperature plastic was madepossible through applied nanotechnology. Nanoparticles are afunctional component of separators and, among other things,ensure their material integrity, nanoporosity, and flexibility.

In abuse tolerance tests, which simulate a variety of im-proper uses, the batteries were overloaded, externally short-circuited, and had nails driven into them. The new separatorpassed all the tests with flying colors. Its most important featuresturned out to be high thermal resistance, chemical resistance,rapid wettability with electrolytes, outstanding charge behav-ior, and complete temperature resistance.

elements21 E V O N I K S C I E N C E N E W S L E T T E R

F U T U R E P R I Z E

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German Future Prize

Access opened to billion-euro market

Evonik Industries has invested € 50 million in the developmentand marketing of the new lithium-ion battery components, andin the construction of production and pilot facilities – and allsigns point to a substantial return on the investment. The newlydeveloped separator could be the key to acquiring the hybridvehicle and stationary battery markets. According to forecasts,the market for lithium-ion battery materials will grow from itscurrent size of about € 1.4 billion to € 3.9 billion by the year 2015.

The benefits would be felt by a host of industries along therelevant value-added chains. There is enormous growth poten-

tial in the area of hybrid cars, for example, which combine theadvantages of two different power trains. Depending on thedriving situation, combustion engine and electric motor operateindividually or in tandem. This promises not only better accele-ration, but above all fuel savings of up to 30 percent. Accordingto estimates, more than 70 different models of hybrid car shouldbe available in the year 2010. The overall sales figure is estimat-ed to be 1.2 million vehicles for that year, with 6.5 million fore-cast for 2015. Today, that figure is about 500,000. Hybrid cars,in particular, would profit from the new technology. These ve-hicles currently run on nickel-hybrid batteries, which are lesspowerful and heavier than lithium-ion batteries and also con-serve less fuel. Lithium-ion batteries, which have eliminated thesafety risk, would be revolutionary for this market. EvonikIndustries is currently using a Honda Civic equipped with a bat-tery prototype to demonstrate that the SEPARION®-based bat-tery technology is already application-ready and suitable foreveryday use. The car has already logged 45,000 kilometers(about 27,962 miles).

Another field of application just waiting for large-formatbatteries is regenerative energies. Large lithium-ion batteriescould make a major contribution to temporary power storagefor utility-independent solar installations, for example, or to bal-ancing the utility supply by stabilizing the electricity grid. Polit-ically, a clear course has been set for renewable energy sourcessuch as the sun or wind for the sake of greater independencefrom fossil energy sources. This is why energy suppliers are obli-gated to integrate decentralized power supplies into their grids –for example, the excess energy from private photovoltaic units.While these measures mean increased operating expenses forgrid operators and future expansion of the grid, the costs can bereduced if large-format batteries are used for load leveling. >>>

Nominated for the German Future Prize 2007: Prof. Paul Roth (left),Dr. Andreas Gutsch(middle), and Dr. Gerhard Hörpel(right)

BMBF initiative for lithium-ion batteries startedEvonik Industries, BASF, Bosch, Volkswagen, and Li-Tec are embarking on an R&D initiative with the Federal Ministry for Education and Research(BMBF) for the development of “Lithium-Ion Batteries for Mobilizing Re-generative Energies of the Future and Increasing Efficiency in the Conversion of Fossil and Regenerative Energies.” The initiative is slated to last three years.The BMBF is funding the projects with some € 60 million.

Research initiative with the German Research Foundation (DFG) With regard to advanced development of the technology, Evonik has joinedthe German Research Foundation (DFG) to support an initiative on the topicof “Functional Materials and Material Analytics for High-PerformanceLithium-Ion Batteries.” The objective of this initiative, in which several uni-versities and institutes are involved, is basic research on lithium-ion tech-nology. Evonik is participating in the initiative with its own research project.

Hybrid cars and tempo-rary power storage in the use of regenerativeenergies are highly promising fields of application for large-volume lithium-ion batteries with SEPARION®


Rollable ceramics: The film used as aseparator in lithium-ion batteries isultrathin. Because of the strongresponse among battery manufacturersand the great market potential, Evonikhas now installed an additional plant for producing SEPARION® and now has a capacity of three million squaremeters per year

These are just two areas in which growth is virtually pre-programmed. Other conceivable areas of application would berecreational applications, such as boats or lawn mowers, wheremarket volumes are smaller, yet still nothing to be ignored.

In addition to separators, Evonik has expanded its portfoliofor battery components with increased safety and power: TheKamenz site near Dresden already produces high-performanceanodes and cathodes. At the same site, the midsized companyLi-Tec builds large-scale lithium-ion cells and batteries. As earlyas 2005, Evonik Industries had established a joint venture withJapanese battery manufacturer Enax as a forward integrationmeasure. Ready-made electrodes are manufactured in China onthis basis, while the joint venture markets powerful anodes andmanganese-based cathodes.

In all, Evonik has already produced several hundred thousandsquare meters of separator film. Based on the positive responseand in light of the great market potential, the company has installedan additional plant for producing the separator film. With a capaci-

ty of three million square meters per year, the plant marks thecompletion of the first step from pilot to commercial production.

Where does the whole story begin? A small, creative, andvisionary group built around Prof. Michael Dröscher, head ofInnovation Management Chemicals, identified the topic “Mem-branes” and their market potential in the “Screening Commit-tee,” the predecessor of today’s Creavis. The researchers identi-fied this topic at a time when lithium-ion batteries and theirapplication in automobiles were nothing more than a vision.The so-called Membrane Team turned this fantastic vision intoreality. Under the wings of Dr. Gerhard Hörpel, the team con-sisted of Christian Hying, an expert in membrane technologyand today responsible for SEPARION® separator production;Volker Hennige, a ceramics expert, who currently heads thelithium-ion activities of Creavis in China; and Sven Augustin,with his membrane application and market background, who iscurrently responsible as a battery expert for automobile appli-cations in Evonik’s Automotive Industry Team.


F U T U R E P R I Z E

CathodeSeparator

Anode

The German Future Prize was awarded for the eleventh time in 2007. Fourteams were nominated by Federal President Horst Köhler in Berlin for the finalson December 6. Through the project “Small Holes, Big Impact” by NanionTechnologies GmbH from Munich and the University of Freiburg, the develop-ment of new medicines can be accelerated and their effects on human cellstested more precisely, less expensively, and faster. Ultraprecise projection processes revolutionize the “Production of the Computer Chips of the Future,” –a project of Carl Zeiss SMT – and promise long-term security for the develop-ment of the technology. For the project “Light from Crystals” – a joint develop-ment of Osram Opto Semiconductors GmbH and the Fraunhofer Institute forApplied Optics and Precision Engineering – new manufacturing processes areused to generate ultraefficient, long-lived light sources that can serve as an envi-ronmentally safe substitute for conventional solutions. It is not possible to applyfor the Prize; authorized institutions may submit to the jury up to three recom-mendations per call for application.

The development could create 1,000 new jobs in Germany

This team has acted as the nucleus for our lithium-ion activities.One hundred new jobs have already been created through theresearch and development of the new separators and additionalbattery components. If the level of growth comes even close topredictions, the number of jobs will increase tenfold in the nextfew years. The way appears paved for lithium-ion technology tobring back expertise and, with it, jobs to Germany.

Part of those jobs are in the German state of Saxony, home ofLi-Tec Battery GmbH & Co. KG, where Dr. Andreas Gutsch isthe managing director. Li-Tec has produced lithium-ion cellsand batteries in cooperation with Evonik at the Kamenz site inSaxony since October 2006. Gutsch was head of Creavis beforemoving to Li-Tec in 2007. “In just a few months, we have creat-ed 50 jobs in Kamenz. But our potential for this technology is fargreater.” Dr. Gerhard Hörpel adds: “We are convinced of theenormous market potential of this application.” The problem:Skilled labor is hard to find. Gutsch: “We are desperately lookingfor engineers ready to join us on our growth path.” Applicantsmust have a pioneering spirit and the courage to innovate. ●


or the fourth time since 2001, the Chemicals BusinessArea of Evonik Industries AG has brought together re-searchers from science and industry for the scientificforum Evonik Meets Science. Some 200 renowned

researchers from Germany and other countries took advantageof the opportunity to learn more about current developments inthe field of chemistry by attending the technical presentationsand discussions held on October 22 and 23. “Our experiencehas shown that we have to link science and industry with eachother in a systematic way. An intelligent transfer of knowledgekeeps Evonik’s innovation engine running smoothly,” said Dr.Alfred Oberholz, the member of the Executive Board of EvonikIndustries AG with responsibility for R&D in the ChemicalsBusiness Area, on the occasion of the forum.

This year, the presentations at Evonik Meets Science focusedon five areas oriented to Evonik’s Areas of Competence. “Eightypercent of our core competencies are represented by these fiveAreas of Competence,” says Oberholz. The areas are Coating &Bonding Technologies, Interfacial Technologies, InorganicParticle Design, Designing with Polymers, and Biotechnology.On these platforms, Evonik combines the know-how, experi-ence, and technologies of multiple business units in the Chem-icals Business Area so that knowledge in the company can bebetter and more selectively converted into concrete solutions.

“A chemical company used to do the research for new prod-ucts, but that’s now outdated,” explained Oberholz. “We now haveto move up the value-added chain and think in systems. Systemintegration is becoming an increasingly important topic.” Thework of the chemical industry, in particular, increasingly over-laps with industries such as biotechnology, nanotechnology, medi-cine, photonics, and electronics.

Oberholz cited the example of lithium-ion batteries to ex-plain this approach: “To put it simply, we used to develop the var-ious powders for making anodes, cathodes, and separators. To-day, however, even though we are a chemical company, we alsohave to understand the interplay of the components in a batterycell if we want to be able to supply our customers and businesspartners with new innovations.” This does not mean, of course,that the company has to start manufacturing the cells or even thebatteries itself. Indeed, companies must always make a clear dis-tinction between what belongs to their core competencies andwhat does not. At the opening of the scientific forum, Dr. KlausEngel, chairman of the Chemicals Business Area at Evonik In-dustries AG, pointed out the importance of Evonik’s innovationsin this area: “The market for lithium-ion batteries will grow toten billion euros over the next decade.”

In the Chemicals Business Area, about 2,300 employees workin R&D at more than 35 sites worldwide. The business area also

Intense Dialogue between Science

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E V O N I K M E E T S S C I E N C E S C I E N T I F I C F O R U M

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and Industry

maintains over 250 partnerships with universities and other re-search institutes, in which it invests over € 10 million per year.According to Oberholz, innovations are possible only if Evonikcan collaborate on R&D with external research institutes. Suchpartnerships also require intense dialogue – for which EvonikMeets Science regularly provides the space. “Because people,”says Oberholz, “are the most important resource for innova-tion.” ●

Some 200 researchers from Germany and abroadanswered the invitation to Evonik Meets Science.Photo right: Dr. Alfred Oberholz,Member of the Executive Board of Evonik Industries AG

Dr. Klaus Engel, Member of theExecutive Board of Evonik Industries AG


DR. EMMANOUIL SPYROU

he economic importance of powder coatings hasgrown continuously since the 1980s. Twenty yearsago, less than 200,000 metric tons were producedworldwide. Today, that figure has risen to about

1,300,000 metric tons. At 38 percent, Asian manufacturers ac-count for the largest share, followed by Europe with 35 percent.There are a number of reasons for the success of powder coat-ings: They are environmentally safe, cost-effective, have goodmechanical properties, and are easy to process. This especially

H I G H LY R E A C T I V E P O W D E R C O AT I N G S E X P A N D T H E R A N G E O F A P P L I C AT I O N S

Breakthrough in Storage Stability

T applies to polyurethane-based powder coatings, which not onlyshow good weather resistance but a balanced ratio of hardnessto flexibility.

Because of the high reactivity of their starting compounds,however, these systems needed isocyanates – blocking agents,such as caprolactam, that prevent sudden cross-linking. Theseblocking agents are released when coatings are cured, and soare undesirable both environmentally and economically. This iswhy emission-free PUR powder coatings that emit neither sol-

Evonik has succeeded in significantlyreducing the curing temperature forpowder coatings with the help of special catalysts. This means it is nowpossible to coat temperature-sensitivesubstrates, for example high-qualitykitchen furniture, with powder coat-ings that protect them reliably againstUV light


C O AT I N G & B O N D I N G T E C H N O L O G I E S

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Thanks to Purified Formulation

vents nor blocking agents were developed in the early 1990s. Inthe future, this unusually complete lack of emissions will gaingrowing importance in the wake of increasingly more stringentenvironmental restrictions.

The mechanism of internal blocking consists in the forma-tion of a four-membered heterocyclic compound from two iso-cyanates each. At temperatures of 180 °C (356 °F) or higher,these “uretdiones” can be broken down again uncatalyzed. Theisocyanates that reform react under these conditions with resins

Unit of Evonik Industries has succeeded in untying this GordianKnot, and developed emissions-free, low-temperature-curingpowder coatings that nevertheless show remarkable storagestability.

To better understand the reaction, researchers carried outmodel tests in solvent, which simplifies the reaction sequence,allowing it to be controlled with greater ease and precision. Asuitable catalyst, such as tetra alkyl ammonium carboxylate(TAAC), which reaches at least moderate reactivity, is used to

containing hydroxyl groups to form polyurethane compounds.Now, through the use of special catalysts, it is also possible tolower the curing temperature considerably. As a result, temper-atures need be no higher than 130 to 140 °C (266 to 284 °F) – inunique cases, even 120 °C (248 °F). This represents a consider-able advantage over previous systems, because under these con-ditions, even temperature-sensitive substrates like wood, MDFplastics, and special aluminum alloys can be coated.

Low-temperature-curing powder coatings with good stability

These highly reactive powder coating systems, with their lowcuring temperature, present not only advantages, for this featureused to severely limit the storage stability of powder coatings.This is why, as a rule, they must be stored in a cool place and are,therefore, expensive to handle. Glycidyl methacrylate (GMA)based powder coatings, for example, are used as a clear coatingin high-quality automotive coatings. There are two reasons forthe lack of storage stability: One is that undesired reactions canoccur even at room temperature. The other is that the coatingparticles in these kinds of systems tend to sinter due to physicaleffects. For the first time, the Coatings & Colorants Business

lower the reaction temperature. The activity can be increasedsignificantly, however, by using another compound that con-tains epoxide groups. After 30 minutes, the conversion rate ap-proaches nearly 100 percent.

In additional tests, researchers were able to prove that agreat deal of the reaction had already run in the first several min-utes. With powder coating formulations that are homogenizedat up to 120 °C (248 °F) in the extruder, this could lead to un-wanted preliminary reactions. Also, a slightly delayed curing isactually an advantage in the case of powder coatings, because itgives the powder melt more time for a smooth film formation.This is why the “catalyst duo” was expanded by a third compo-nent, which consists of a carbonic acid that does not significant-ly impair the total reaction, but has a big impact on the progressof the reaction. Only when the acid is almost entirely consumedby reacting away internally does the reaction between the uret-dione and alcohol really begin – and this results in the desiredtime delay.

Consequently, in addition to the reaction partners, at leastthree additional components are needed for optimal control oflow-temperature-curing polyurethane powder coatings: the ac-tual catalyst (TAAC, for example), an epoxide, and an acid. As arule, the latter is already supplied through the hydroxyl >>>

Formation and cross-linking of uretdiones

O

1. Cleavage2. Film building

C + OH-Polymer

Isocyanates

R – N + N – R

Uretdione

O

=O

CR – N N – R

CO

===

---

-=

C ==

NH

Polyurethane

–O – Polymer

O

==


polyester resins that are used. Depending on the manufacturingprocess, these resins still contain acid groups.

The following reaction mechanism between these threecomponents seems plausible: The carboxylate of the catalyst re-acts with the epoxide under formation of an alcoholate. The car-boxylate is neutralized directly by the free acids, and a new car-boxylate is formed. Only when this cycle is interrupted by theuse of the entire acid can the alcoholate – the actual reactivecomponent – unfold its effect. We must begin with the assump-tion that the reaction in the catalyst mixture is stoichiometric –

DR. EMMANOUIL SPYROUEmmanouil Spyrou works in research and development at Evonik’s Coatings &Colorants Business Unit, where he isresponsible for the radiation curing andpowder coatings research areas.

+49 2365 [email protected]

Reaction curves in the catalysis of the uretdione and alcohol reaction. The desired time delay of the reaction occurs only with the addition of acid.This is necessary for a good reaction and prevents pre-reactions duringprocessing in the extruder

■■ No catalyst ■■ + Catalyst ■■ + Catalyst + Epoxid ■■ + Catalyst + Epoxid + Acid

an important consideration in formulation, since epoxide hasalways to be present in excess relative to the total quantity ofcatalyst and acid.

Additional improvements are already underway

It is also clear from the reaction sequence that, with differingconcentrations and identities of the three components, a greatmany formulations are possible. Researchers worked with theliquid model system here, too, to achieve manageable results. Inthe final analysis, further development involves the optimizationof each individual component – and, at the same time, all compo-nents, because whenever one component is changed, it affectsthe other two. The resin used also plays an important role, as itmust ensure a smooth coating surface while also preventing thepowder coating particles from blocking or sticking. In all, thechanges take place in properties of reactivity, flexibility, reactionsequence, and storage stability. On the other hand, this alsomeans that additional improvements are possible in the profileof characteristics of powder coatings, because many combina-tions have not been tested at all yet. Developments in these areasare already underway.

Today, there are formulations available that completely curewithin 30 minutes at 140 °C (284 °F) in a circulating air oven.Their reactions progress well and they are also sufficiently flex-ible. Their storage stability is their most notable feature, how-ever. These systems can be stored for two weeks at even 40 °C(104 °F) without any significant changes to their coating prop-erties. Appearance (smoothness) and gloss, which are normallyweak points of conventional low-cure powder coatings, areparticularly consistent. The stability achieved at 40 °C waspreviously unreachable for highly reactive emission-freepowder coatings. In this regard, the new powder coatings are amilestone in tapping additional applications for environmental-ly friendly powder coatings. More improvements in the formu-lations and the catalyst system are already underway, and willgive these special coatings even greater momentum. ●

Postulated mechanism of catalyst activation. The actual reactive component –the alcoholate – only reacts when the acid is consumed almost completely

NCO concentration at 140 °C

100

80

60

40

20

00 5 10 15 20 25 30

Time [min]

NCO [%]

Epoxide

Tetraalkylammoniumcarboxylate

Acid

Alcoholate

Carboxylate + Alcohol

mailto:[email protected]



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In the automotive industry, coatings and coating processes have achieved a high standard in terms of weather and mechanical resistance. What is more, they allow a wide array of hues andeffects. But cost pressure, regulations, and the push to save energy are forcing researchers to search for new processes and materials.

A U T O M O T I V E C O AT I N G S

The Silent Revolution

PROF. DR. THOMAS BROCK

or many years, vehicle coatings have had a classical, pri-marily four-layer structure that protects the body of thecar against rust and mechanical damage, and providescolor and different effects. The first layers applied to the

metallic carrier material made of steel, aluminum, or zinc, is aphosphate layer and an electro-dip primer, which provide cor-rosion protection and adhere extremely well to the metal sheet.A filler applied on top smooths any roughness in the undercoatso it cannot be seen when the very thin coating is applied. It alsoprotects the layers underneath against stone chipping. The basecoat, which goes over the filler layer, is the color-bearing layerthat is also responsible for a metallic or a pearl finish, for example.As the final layer, the clear coat protects the layers underneathagainst chemical and mechanical influences, and the effects oflight.

This classical coating system and its means of application areset to undergo a number of changes over the next years, how-ever. One factor will be cost pressure, which will have an impacton the choice of materials, energy consumption, and processtimes. Legislative and health-related restrictions, as well as newrequirements governing the quality of effects, functionality, andperformance, will also play an important role.

One standard that the coatings industry has already con-tended with for years is the use of lower quantities of solvents.In the United States, the biggest demand is for high-solids sys-tems, which use special media with a tight relative molar mass,and two-component systems, depending on the area of applica-tion. On the other hand, water-based and powdered coatings arethe preferred choices in Europe and, to some extent, Japan. Mostwater-dilutable coatings contain water-dispersed or emul- >>>

F

Although automotive coatings are already high in quality, research continues at breakneck speed


sified polymers. Practical experience has proven thatchanging to water-based coatings can reduce sol-

vent emissions from production lines by two-thirds to three-quarters – even when the clearcoat contains solvents and only the base coat, fil-ler, and electro-dip primer are water-based.

New processes for drying and curing are alsobecoming more important – or at least the sub-

ject of more intensive research. For “low-bake”processes, the industry is looking for ways to bake

or cure at lower temperatures. Modified coatingsare currently in various phases of testing. In some

cases, drying processes such as those first used forcoating wood – using dry, evenly warm air – can also be

used for water-based automotive coatings. This technology,however, is specially suited to new plants, so only a few manu-

facturers are currently using the process – Daimler, in its vanfactory in Düsseldorf, is one example. In automotive repair andin the refinishing phase of the production process, but above allin coil coating, near infrared technology (NIR®, KIR®), in whichthe coating is cured through energetic, shortwave IR radiation,is gaining prominence. The methods are not used (yet) in serialproduction, however, because of the fact that, for convincingresults, the distance between the metal sheet and the heat sourcehas to be precisely maintained – not an easy task given the ge-ometry of a vehicle.

In the near future, UV curing will almost certainly be the pro-cess of choice for vehicles in the upper price ranges, given thefact that coatings cured by this method can be further processedquickly and show a high degree of scratch resistance. A two-component isocyanate curing method is also used in the cavities

Nanofinishing for automotive coatings:

interference on effect pigments coated nanothin

From the driver’s perspective, the carcoating must provide reliable protec-tion against chemical and mechanicaldamage and the influences of light. It also has to look good. This way, hegets years of enjoyment from his car.From the industry’s point of view, the materials and painting processesmust also be cost-effective, consumelittle energy, and emit as little solventas possible


that cannot be easily reached by UV light. Compared to UV cur-ing, light radiation curing, which is still in the basic research stage,would require fewer safety precautions and consume less ener-gy in a production line.

Technically, the electrostatic spray coating of plastic parts isalready feasible. But the conductive plastics required for themethod make the technology too expensive. Conductive under-coats and new plastics with increased conductivity, as well astechnical “tricks,” should pave the way for electrostatic plasticscoating.

Nanotechnology is also making its mark on the world ofautomotive coatings, where nanoparticles ensure, for instance,improved cross-linking of the coating layer. Tests in acceleratedweathering plants and with scouring materials, for example,have shown that coatings with nano-linked polymers maintaintheir shine longer than conventional clear coatings. Chemicalcompounds called “dendrimers,” whose structure resembles abranched tree, in which the “branches” consist of repeating unitsof the base molecule, could be attractive for base and clear coat-ings. Dendrimers have been so expensive to produce, however,that research is concentrating on hyperbranched polymers,which have similar properties, although they are neither as roundnor as highly symmetrical as dendrimers. Even if these mediaare expensive now, their use in the coatings of the future is as-sured. They could, for example, protect the base coat and the fil-ler against stone chipping. “Nanofinishes” are already ensuringhigher soil repellency and longer life for transparent plastic partssuch as headlight covers and glass.

An already well-established direction of development forautomotive coating chemistry has led to soft-feel coatings withskin-friendly “haptics,” such as on dashboards or door handleshells. While the industry relied on films and adhesive technolo-gy for such applications in the past, it is now frequently turningto plastic coatings embedded with polyurethane spheres. Thelatter ensure that the coating surface feels soft. R&D is also con-sidering functional surface effects for completely differentareas: One example is coatings with chemical fingerprints thatprovide additional security against theft. In this application, thecoating contains a chemical bar code that can then be read bymeans of a scanning technology. Another example is piezoelec-

trical coatings with electrically active polymers to replaceswitches as pressure sensors. Both applications are still relative-ly far from practical use, however.

In the intermediate term, the automotive industry will elim-inate the filler from the current system of coating layers – somepaint shops have already done so. The primer and base coatingswill assume the tasks of the filler, and thereby help reduce ener-gy consumption by 30 percent and costs by 20 percent. Over thelong term, the car body will not even have an electro-dip primercoat. Instead, the metal will be pretreated by other “integratedpretreatment” methods, including sol-gel processes or self-organizing monolayers.

Whatever innovations arise over the next few years, the goalof the automotive industry is to lower costs and further simplifyprocesses. This can be done through fewer coating layers, forexample, but also through complete automation of the pro-cesses, as well as modular, decentralized production with pre-cisely reproducible shades of color. Finer atomization of paintparticles with ultrasound or laser for reproducibly thinner lay-ers would also meet the industry’s objective. No matter whattechnique eventually prevails in the industry, it should, and will,go completely unnoticed by the consumer, as long as thechanges are confined to the “interior life” of coating layers. Tothe customer, then, the only improvement in the automotivecoating will be its durability and looks – truly a silent revo-lution. ●


PROF. DR. THOMAS BROCKThomas Brock has been Professor in Coating Technologyat Niederrhein University of Applied Sciences in Krefeldsince 1995. Previously, he spent ten years developingautomotive coatings for DuPont Performance Coatings,the former Herberts GmbH. Most of his work is focusedon measuring and testing technology, rheology, coatingproduction, and the various coating processes and typesof application. Currently, he is chairman of the “CoatingsChemistry” division (previously: APi) of the Society ofGerman Chemists (GDCh).+49 2151 [email protected]

Clear coat

Color-bearing base coat

Filler layer

Electro-dip primer

Phosphate layer

Metal

Most current automotive coatings have a four-layer structure, includingthe electro-dip primer, filler layer, color-bearing base coat, and clear coat



DR. HANS G. BÖRNER

he key to the function of proteins is their structure,which is determined via a hierarchical structure for-mation process over four distinguishable levels. The se-quence of the individual amino acids within the linear

polypeptide chain determines the primary structure, while theformation of basic structural elements such as the α-helix andthe �-sheet governs the secondary structure. The three-dimen-sional organization of these simple secondary structure elementsthen defines the tertiary and finally the quaternary structure ofproteins.

Taking this simplistic structure formation principle into ac-count, the controlled integration of defined peptides into syn-thetic polymers to transfer biological principles into syntheticpolymer systems is gaining importance. Hence, combining seg-ments of monodisperse, monomer-sequence-controlled peptideswith synthetic polymer blocks enables one to access bioconju-gates. These might allow envisioning new possibilities for poly-mer chemistry by the direct translation of structural and func-tional principles of biology into synthetic polymer sciences.Peptide segments combine the possibility of defined self-assem-bly with the potential to actively interact with biological sys-tems. Thus, bioconjugates can be potentially used to programstructural formation processes in polymers and generate bioac-tive polymeric materials. In short, the goal is to understand andcontrol intermolecular interactions between sequence-defined

peptides. Specific interactions can be used in a broad spectrumof applications, such as organizing macromolecular buildingblocks (supramolecular chemistry with macromolecular LEGO®

bricks), controlling the release of drugs from polymeric carriersystems, generating affinities to (bio-)surfaces, and stabilizing avariety of interfaces, most importantly those between biologicalsystems and synthetic materials.

Broad synthesis routes to versatile polymer bioconjugates

At the Max Planck Institute of Colloids and Interfaces in Golm, aresearch group is focussing on the synthesis and investigation ofhighly defined polymer-peptide conjugates. Researchers devel-oped and implemented a variety of access routes to integratemonodisperse oligopeptides with defined monomer sequencesinto synthetic polymers. Primarily two approaches are utilized:A grafting method, in which synthetic polymers are polymerizedfrom a defined position of a peptide. In this method, initiatorfunctionalities are integrated into an oligopeptide at a specificsequence position. By using controlled radical polymerizationtechiques, such as ATRP (atom transfer radical polymerization)and RAFT (reversible addition-fragmentation chain transferradical polymerization) the synthetic polymer block is synthe-sized in a well-defined manner.

N E W F U N C T I O N S B Y P R O G R A M M E D S E L F - A S S E M B LY

Macromolecular Building Blocks Made

Over millions of years, Nature has created proteins as a versatile platform of biopolymers. They followa simple structural principle in which 20 different building blocks, natural amino acids, are combinedinto linear polypeptide chains. Despite the simplicity of the building block principle, peptides and pro-teins can be found in a broad range of applications, and perform a variety of different tasks in biologi-cal processes. They operate, for instance, as multifunctional systems that define the function of cells,the organization of tissues, the transport materials, or they catalyze chemical reactions as enzymes.

T

Figure 2Integration of monodispersedoligopeptides with a definedmonomer sequence (bio-segment) into synthetic poly-mers. The synthetic methodsdeveloped allow broad access to various systems throughcoupling and polymerizationstrategiesAdapted from: Lutz, Börner, Prog. Polym. Sci., 2007,doi:10.1016/j.progpolymsci.2007.07.005

1-Coupling/ligation 2-Macroinitiators 3-Inverse bioconjugation 4-(Macro)monomers

Polymerization Solid phase synthesis Copolymerization

Biosegment

Polymer bioconjugates (blocks or graft)

+ N3 NH2 O

O

= –=NH

O

= Br


D E S I G N I N G W I T H P O LY M E R S

17

from Polymer-Peptide Conjugates

Figure 1Inspired by the structural principlesof biology: By integrating definedpeptide segments into syntheticpolymers, scientists from the MaxPlanck Institute for Colloids andInterfaces Research in Golm areopening up access to new, complexmicrostructures. Their work demon-strates that the biological principle“form follows function” can also beapplied to the material sciencesAdapted from: Förster et al., J. Mater.Chem., 2003, 13, pp 2671–2688,and Protein structures from PDB

A different approach uses regioselective coupling methods,including the highly specific “click” coupling reaction, to ligatepolymers with defined end functionalities to complementarygroups in a peptide segment. These broad access routes allowfor the integration of basically the entire variety of classical syn-thetic polymers available (s. Fig. 2).

Biomaterials are highly optimized to their purpose and fre-quently superior to synthetic materials. This results often fromhierarchical structures, facilitated and guided by proteins, pep-tides, and saccharides. Scientists in Golm transferred this bio-logical concept of peptide-guided structural formation to synthet-ic polymers and polymer materials. For that a variety of peptide-based organizer units was studied, as depicted in Fig. 3 (p. 18).

The motif of the �-sheet was closely studied as one of thethree secondary structural elements, because interesting tape-like, fibrillary, or tubulary structures could be obtained. Theseare not only important structural and functional elements innatural materials, but they also offer a wide variety of possibleapplications in synthetic materials. Such elements might allowthe generation of interesting properties, such as anisotropicstrength and elasticity, defined positioning of chemical func-tionalities, and the directed transport of materials. This mightallow addressing applications such as, for instance, as fiber com-

ponents in composite materials for lightweight construction, asnanowires for printable electronics, or as scaffolds for tissueengineering for biomedical applications.

Building blocks with switchable functions

The functions of peptide segments in peptide-polymer conju-gates can be temporarily disturbed by selectively integratingdefect segments. This enables the realization of switchable build-ing blocks that have been demonstrated to be useful tools forpeptide-guided microstructure control. The functions of thepeptide, however, is only temporarily disturbed and can beswitched on again controlled via the pH value. Exploiting thisconcept conjugate systems composed of poly(ethylene oxide)and peptides have been realized that spontaneously organizeinto macroscopic tapes with lengths of several millimeters afterswitching the organizational tendency of the peptide segmentON. An analogous peptide segment attached to poly(n-butylacrylate) leads in organic solvents to the formation of nanosco-pic spring structures as depicted in Fig. 4 (p. 18).

The combination of polymers and monodisperse peptidesallows for the expansion of the structural and functional spaceavailable for classical block copolymers, and potentially >>>

Wormlike micelles

Vesicles

Amphiphilc AB-block copolymer

Micelles

Acetylcholine receptor Green fluorescent protein Ribonuclease inhibitor Chaperon complex

might broaden the platform of polymerssignificantly by exploiting the structureformation properties of peptides. The ra-tional design in these bioconjugates iscurrently addressing the secondary struc-ture level, and transduction of informa-tion in terms of complex, hierarchical self-assembly processes is still not fully under-stood. Even if the research is fundamentalin nature to understand the basic interac-tions and behaviors of such systems, it al-ready enables one to envision possibili-ties and potentials also interesting forindustrial applications. Biomedicine andpharmacology, for example, offer fieldsof application for bioactive polymer ma-terials and highly defined functionalpolymers. Even now, bioconjugates com-posed of poly(ethylene oxide) and pep-tides are being tested as carriers for anti-tumor agents in cancer therapies. Appli-cation here can specially address lymphat-ically spread metastatic tumors that can-not be easily reached via conventionalblood distributed carrier systems.

It is predictable that polymer chem-istry with its inherent molecular weightdistributions will evolve to macromo-lecular chemistry with precisely definedmolecules. Hence, the synthesis of fullysynthetic, monodisperse polymers withdefined monomer sequences will be oneof the upcoming challenges in polymerscience. Completely unnatural polymerclasses might be developed, which com-bine novel units capable of specific mo-lecular recognition with new monomeralphabets to fine-tune secondary interactions along linear poly-mer chains. The study of the sequence-structure-property re-lationships of these entirely synthetic macromolecules has tofollow.

Non-peptidic, monodisperse polymers with precise function-alities and functions offer enormous advantages. Particularly inthe arreas of pharmacological and biomedical applications.Toxicological studies might be less expensive and licensing pro-cedures could be dramatically simplified. There are also severalbenefits foreseeable for materials sciences. Selectivity, specific-ity, and, above all, bioactivity could be incorporated into mate-rials as realized already in biological materials. The methodsintroduced here might be attractive for the area of renewableraw materials, too. Polymers built from amino acids are mostlikely one of the first platforms to compete with classical poly-mers, made from fossil raw materials, and then well-definedcompatibilizers are required. ●


DR. HANS G. BÖRNERHans G. Börner is currently an EmmyNoether Fellow of the German ResearchFoundation (DFG) and head of an inde-pendent research group in the colloidchemistry department of Prof. MarkusAntonietti at the Max Planck Institute forColloid and Interface Research in Golm.His research interests are focused on thesynthesis, the characterization, and theapplication of polymer bioconjugates toestablish and control well-defined inter-actions in macromolecular systems.

+49 331 567-9552; [email protected]

Figure 3The concept of peptide-guided organization of synthetic polymersAdapted from: Börner, Macromol. Chem. Phys., 2007, 208, pp 124–130

Figure 4Peptide-guided organization of a polybutylacrylate peptide conjugate in organicsolvents (diagram of the activation of the peptide organizer (left) and aggregationto a nanoscopic coil spring [middle and structural model right])

1. Linear peptides

2. Preorganized peptides

3. Cyclopeptides

Nano and microtapes

Nanostructured tapes

Core-shell tubes

Peptide organizers Polymer-peptide conjugates Structures

Structure model

Distorted �-sheet

AFM

Switch

on

off Self-assembly



HANS-ULRICH PETEREIT, DR. NORBERT WINDHAB

he importance of effective active ingredients to theadvances of modern medicine cannot be denied. Justas much value is placed on the development of inno-vative pharmaceutical forms, which make it possible

to create the actual drug from the active ingredient. Advanceddrug delivery systems ensure that an active ingredient is trans-ported from the site where it is applied to the site where it canbest fulfill its therapeutic function.

These kinds of “shuttles” can, for example, transport an ac-tive ingredient unimpeded through the stomach and into the in-testine. Building on the many years of experience of the PharmaPolymers Business Line, the drug delivery platform EUDRAGIT®

of Evonik Industries has already proven itself in a variety of ap-plications. The EUDRAGIT® family is based on pharmaceutical

coatings that can be used to coat cores of active ingredients, orin which active ingredients can be embedded.

EUDRAGIT® is made of polymethacrylates to which func-tional groups have been added. These functional groups areneeded to equip the shell of these special pharmaceutical formswith defined release mechanisms. The polymethacrylates of theEUDRAGIT® system are an excellent means of coating substrates,crystals, pellets, tablets, or capsules with a shell that resists stom-ach acids. The choice of polymer allows selective control overthe release site of the active ingredient in the digestive tract.

In principle, there are two different methods of controllingthe release of the active ingredient: One dissolves the shell in adefined region of the human body in reaction to the pH valuepresent in different regions of the human gastrointestinal >>>


D R U G D E L I V E R Y S Y S T E M S

Conveying Active Ingredients to the Cell Interior

With the help of low-molecular meth-acrylates, Evonik Industries researchershave created a new basis for highly specific drug delivery systems for futurenucleic acid therapies. The company has also developed an additional platformfor oral applications based on an endog-enous substance to improve the intake of active ingredients into the blood-stream via the intestine. In the future-oriented field of drug delivery systems,the company is the world market leaderin the area of controlled release systems,and has already amassed many years ofproduct and formulation know-how.

T


tract, and the other controls the permeability of a polymer that isinsoluble under physiological conditions by means of itscharacteristic properties and the coating thickness.

Dissolution can be controlled through the pH value, for ex-ample, with the help of an amino function in a side chain of a cat-ionic polymer such as EUDRAGIT® E. The coating is acid-solubleand is used for applications in the stomach, with the shell pro-tecting against moisture, isolating taste, or preventing unwant-ed staining. By contrast, the associated anionic polymers in theform of EUDRAGIT® L are equipped with carboxyl groups thatallow release in the basic environment. These kinds of coatingsare already used in medications that are resistant to gastricjuices. After passing through the stomach, the tablets dissolve inthe intestine as a result of the basic environment and release theactive principle for absorption in the bloodstream.

Diffusion-controlled release of active ingredients, indepen-dent of the pH value, offers an alternative to these systems. Suchcoatings enable the development of “delayed-release medica-tions,” which release the active ingredient over time rather thanall at once, thereby allowing it to work longer in the body.

Ternary complexes as synthetic vectors. The complexesconsist of a cationic lipid (dioleoyltrimethylammonium-propane/ DOTAP), an anionic methacrylate copolymer andan antisense oligonucleotide as active agent. The systemcan be varied through the type of polymer, the amount ofantisense oligonucleotide, and the charge ratio

EUDRAGIT® NE 30 D, a methacrylic acid ester, belongs in thisclass, and releases the active ingredient based on the thicknessof the coating. One version of this system, in which the releaseof the active substance is triggered more flexibly not only by thethickness of the coating but the permeability of the shell, is usedin EUDRAGIT® RL and RS. The effect is achieved with the aid ofquaternary ammonium groups in the pharmaceutical polymer.

Building on these systems, the Pharma Polymers BusinessLine has selectively developed drug delivery platforms. A goodexample is EUDRACOL™ – a technology for targeted transportof the active ingredient through the digestive tract, with pH-de-pendent and time-controlled release. The delivery system, ap-plied in oral dosage forms, consists of an active ingredient core,which is enclosed in several layers of EUDRAGIT®. The outerlayer allows the core to be transported unchanged through thestomach to the end of the small intestine, where it dissolves inresponse to the basic environment. Later on in the process, therelease is diffusion-controlled through the second layer, so thatthe active ingredient is solely released in the colon, where itworks on site or can be resorbed by the intestinal wall.

Interaction with biological membranes

The next logical step in the advanced development of drug de-livery technology is therapy on the cellular level. The big hurdlehere is the protective mechanism of the cell wall, which pre-vents foreign substances from entering the cell. Nature, how-ever, has left open a back door that allows many key nutritionalsubstances and ingredients with biological mechanisms to beactively absorbed by the cells. On the other hand, viruses areable to exploit such mechanisms as gene shuttles, so to speak, orvectors to penetrate the cell wall.

Given these circumstances, the Pharma Polymers unit tack-led the question of whether drug delivery technology can beused to achieve targeted interactions with biological membranesthat enable penetration into the cell. A ternary complex consist-ing of a cationic lipid, an anionic polymer, and an oligonucleoti-de as active agent has proven the key to success, as it takes on thefunction of a non-viral, synthetic vector, and so prevents toxi-cological side effects of the shuttle.

To develop a suitable system, researchers first started fromthe well-known fact that carboxyl functions interact with thephospholipids of the membrane and can destroy them. Anionicpolymers are able to control this interaction with the membraneas a function of the pH level. Based on the company’s own ex-pertise, researchers then developed special anionic methacry-lates that show a lower molecular weight compared to existingEUDRAGIT® systems.

The low molecular weight is important because the applica-tion is no longer oral, but must be administered parenterally byinfusion or injection. The polymeric systems are structured likeEUDRAGIT®, but show a decided difference in that the arrange-ment of the polymer chains in solution now depends on the pHvalue: When the pH value is high, the polymer chains are ex-panded. In acids, however, where the carboxyl residues are pre-sent in a non-dissociated form, a thick coil develops. This me-chanism affects the interaction with the membrane.

Catonic lipid

Active principle

Anionic polymer


The key to genetic therapy is exocytosis: receptor-mediatedabsorption of substances into the interior of a cell. The cationiclipid contained in the ternary complex supports exocytosis. Inthe cytoplasm of the cell, this process leads to the formation ofan intracellular vesicle, the “endosome,” which transports theenclosed material to the lysosome or back to the cell wall and re-leases it there.

The pH value is 5.8 in the endosome, and 7.2 outside thecell. This means that the polymer passes through a conformationchange in the slightly acidic environment of the endosome, andthe active ingredient is released into the cytoplasma, the targetedcompartment. Exocytosis – the transport of the active ingre-dient from the inside of the cell back to the outside – is thereforeimpossible. This mechanism allows the actual active ingredient,the oligonucleotide, to diffuse to the cell core or the endoplas-matic reticulum, the site of the cellular protein biosynthesis.

The system is currently being tested using special blood can-cer cells (T24 cells). In vitro measurements reveal that the ac-tivity of the cells remains unchanged when incubated, either with-out copolymer or as a simple mixture of these three substances.Only the addition of the ternary complex led to a significantdrop in the activity (about 50 percent) of these blood cancercells –proof positive that the specific oligonucleotide was actu-ally released in the cytoplasm and was able to interact in thedesired way with the genetic material of the cancer cells main-taining their vitality. Researchers had thus created a drug de-


The ternary complex consisting of lipid, polymer, and oligonucleotide enters the cell as a Clathrin-Coated Vesicle (CCV) by endocytosis – a type of intro-susception of the cell membrane, in which the complex enters the cell. In theinterior of the cell an endosome is formed. Because of the differing pH values in the endosome and outside the cell, the active agent is immediately releasedfrom the endosome by polymer membrane interaction. Transport back out of the cell – exocytosis – and decomposition of the active ingredient in thefunctionally altered endosome, – the lysosome – is therefore unlikely

Activity of T24 cells depending on cationic lipid and anionic copolymer, measured at the enzyme expression. Complexes without copolymer and simple mixtures of the components have no impact. Only the ternary complex consisting of lipid, copolymer, and antisense oligonucleotide leads to a significant reduction in enzyme expression

livery platform for administering and increasing the activity ofnucleic acid agents. Through targeted release of active ingre-dients in the cytoplasm, a new opportunity opens for selectiveinactivation of malignant genes, for example – a process alsoknown as gene silencing.

Innovation coup with mother’s milk

Another research project planned by Evonik’s Bio Science-to-Business Center aims to tap previously unfeasible oral applica-tions for both new and existing active ingredients. And the frag-ment of an endogenous protein supplies the key. Once again, thestrategy is built on the ability of the EUDRAGIT® system totransport active ingredients unimpeded through the stomachand into the intestine. Because many active ingredients are notabsorbed well here, the system is also equipped with an endoge-nous peptide that promotes absorption into the intestinal cellsand transport of the active ingredient from the intestine into thebloodstream. This concept marks the first time a drug deliveryplatform offering the characteristic therapeutic advantages forthe intestinal tract has become available for oral administrationof many known active ingredients.

A fragment in human lactoferrin was identified as a suitablepeptide. This fragment makes up ten to 20 percent of the pro-tein content of mother’s milk and is also found in other bodilyfluids and, naturally, in the milk of all mammals. Lactoferrin >>>

Extracellular pH: 7.2

CCVExocytosis

Lysosome

Endoplasmatic reticulumEndosome

pH 5.8

Polymer alone

0 20 40 60 80 100 120

Method adopted from Dean NM et al.

Enzyme expression [%]

Cationic lipidsalone

Complexes withoutcopolymer

Complexes withcopolymer and scrambledoligonucleotide

Complexes withcopolymer and oligonucleotide

Nucleus

Lysis

Cell wall

©Release in thecytoplasm


is an extremely large molecule, with a number of small subunits,each of which performs different tasks. Certain subunits areresponsible for the transport of the iron, for example, whileothers are able to interact with the DNA. The latter make up asmall section of the protein molecule, which looks somethinglike an electrical plug, and are arranged on the molecule’s surface.

Because of the genetic code, this fragment is folded in a spe-cific way. Amazingly, the same three-dimensional structure canbe found in the lactoferrin of all mammals, although the peptidedisplays different sequences of amino acids, depending on thegenus. This three-dimensional structure was obviously con-served over the course of evolution because of its function.

The researchers of the Bio Science-to-Business Center havenow succeeded in loading various active ingredient particleswith this human lactoferrin fragment and producing a numberof substance samples for field tests. It also turned out that thissmall addition of peptide on the surface of the active ingredientparticle is already sufficient to produce a shuttle that triggers

strong stimulation of the intestinal cells. This stimulation resultsin a large-volume absorption process, a type of macropinocyto-sis, that significantly increases the bioavailability of active in-gredients in standard tests, or at least makes it possible.

In principle, the process is based on an elaborate trick, sincethe cells recognize the shuttle – which is both invisible and a de-coy – as one of their own. This absorption process was confirmedmany times in later tests. It is, therefore, possible to use a Trojanhorse to gain access to the interior of a cell through cell stimulation.

Findings such as these could potentially open up completelynew paths in pharmaceuticals – both for new medicines and formany known active ingredients that are poorly absorbed by theintestine on their own. These are listed, for example, in BCSClass 3, which includes therapeutic substances for which phar-macists would like to see improved bioavailability. The presentfindings raise hopes that, with the help of innovative drug de-livery platforms, advanced drug therapy will open up complete-ly new opportunities. ●

Sights are set on the next level of innovation: With the help of the EUDRAGIT®

drug delivery system and an endogenous peptide, researchers in the BioScience-to-Business Center aim to improve the absorption of active ingredientsin the intestine, and thereby increase bioavailability. Prof. Dr. Ulrich Schubert,Jena, and Prof. Dr. Roland Brock, Tübingen, among others, are involved in theproject. Dr. Benedikt Hartwig is the project manager at Evonik

HANS-ULRICH PETEREITHans-Ulrich Petereit has headedResearch, Development, and TechnicalService for the Pharma PolymersBusiness Line of Evonik’s SpecialtyAcrylics Business Unit since 1995. His areas of responsibility include development of drug delivery systems.


DR. NORBERT WINDHABNorbert Windhab is Senior ManagerBiotechnology in Evonik’s research unitCreavis Technologies & Innovation in the Bio Science-to-Business Center,where his responsibilities include humanstudies, new pharmaceutical syntheses,and nutritional supplements.


Stomach Intestine Cell Blood

EUDRAGIT®

A certain segment of the human protein lactoferrin (left) enablesthe absorption of various active ingredients into the intestine. The photo on the right shows in vitro how a fluorescent pigmentwas fed into the cells




The company was started 100 years ago as a manufacturer of enzy-matic leather tanning chemicals (mordants). Today, it is the globalleader in methacrylate chemistry: Evonik Röhm GmbH, which repre-sents the Methacrylates and Specialty Acrylics Business Units ofEvonik Industries. “With sales of over € 1.6 billion, these two busi-ness units generate 15 percent of the chemistry sales of the newEvonik Industries, and make an above-average contribution to theGroup result,” said Dr. Manfred Spindler, member of the Manage-ment Board of Evonik Degussa GmbH, at the event celebrating the100th anniversary of Evonik Röhm in Darmstadt in late September.Three hundred guests were in attendance, including internationalcustomers, representatives of politics and associations, as well as VeraRöhm and Dr. Axel Röhm, the grandchildren of company founderOtto Röhm.

The event included a scientific colloquium, during which Dr. KlausAlbrecht, head of Innovation Management for the Methacrylates

news

larger quantities of acrylic acid esters and, finally, developed for theautomotive industry a completely transparent safety glass with an in-terior acrylic layer, the production of which started in 1928.

The breakthrough came in 1933 with the registration of the trade-mark for PLEXIGLAS® – the first completely transparent plastic, whichwas originally painstakingly polymerized between two plates of glass.Even back then, the cast plates impressed the beholder with the samequalities of transparency, brilliance, unsurpassed aging resistance,formability, and fracture resistance that are valued today. “The successof plastics was possible largely because of the evolution of improvedmethods for systematically processing them into finished or semi-fin-ished products,” said Albrecht. Today, multiunit injection-moldingmachines are taking over complex manufacturing processes and thushelping develop increasingly efficient solutions in large-scale produc-tion. Extrusion technology has also reached a quality very close to thatof cast plates. Only for the kind of ultrahigh-molecular PMMA grades

Dr. Klaus Albrecht, head ofInnovation Management

for the MethacrylatesBusiness Unit (left) and Dr.Manfred Spindler, member

of the Management Boardof Evonik Degussa GmbH

Business Unit and head of R&D in the Molding Compounds BusinessLine, led some 50 university scientists through the company’s history.“One of Otto Röhm’s great achievements was to help further ourunderstanding of polymers by systematically working with acrylates,“said Albrecht. Once the new company – established on September 6,1907 by Röhm and his friend Otto Haas for the manufacturing ofenzymatic products – had made enough income for research purposes,he put together a research team that continued his work since the1910s on the synthesis and polymerization of acrylic acid, and on meth-acrylic acid as a somewhat later focus. All activities were based onRöhm’s 1901 dissertation “Polymerization Products of Acrylic Acid.”

The team systematically studied the properties of acrylic plasticsand were not discouraged by the lack of technical difficulties. Indeed,Röhm described a synthesis pathway for acrylic acid from ethyleneearly on. Because there was insufficient research on stabilization ofthe monomers, the compounds had to be cleaned in small quantitiesin completely darkened laboratories. Otherwise, spontaneous poly-merization would occur. Little by little, the team was able to produce

used in aquarium panes or airplane windows does casting remain themethod of choice.

But Evonik Röhm has long offered more than just the high-qualityplastic PLEXIGLAS®. The Pharma Polymers unit produces methacry-late-based polymer coatings that can be used to control the rate or lo-cation of the release of active ingredients, and the subsidiary EvonikRohMax supplies oil additives that help improve the viscosity of lubri-cants and gear and hydraulic oils; they ensure that oils have uniformlygood lubrication properties over a range of temperatures.

“Otto Röhm was ahead of his time,” said Spindler. “He was solid-ly convinced that the results of his dissertation amounted to a technol-ogy platform that he could use to build a completely new business –twenty years before the seminal work of Hermann Staudinger laid thegroundwork for polymer chemistry.” Success has proven him right –today, Evonik, with its Methacrylates and Specialty Acrylics BusinessUnits, is the global leader not only in methacrylate chemistry, but alsoin specialty monomers for paints, dispersions, and adhesives, and isthe world’s second-largest supplier of PMMA molding compounds.

+++ Evonik Röhm: 100 Years of the Future


What are the latest developments in the field of printable electronics?What materials can be used to produce innovative, flexible flat screendisplays? What materials can be used to produce flexible, inexpensivesolar cells? These and other questions were the focus of NanotronicsSummer School 2007, which Creavis Technologies & Innovation, theR&D unit of Evonik Industries, held in September in a complex locat-ed just outside the gates of the Marl Chemical Park.

About 80 scientists from 25 universities and research institutesgathered with experts from Creavis to discuss current developmentsand results from the projects of the Nanotronics Science-to-BusinessCenter. Other participants included research groups working withCreavis in bilateral research partnerships, and representatives of theDispersion Systems for Electronics Applications Graduate College ofthe University of Erlangen-Nuremburg, and “Nanotronics – Photo-voltaics and Optoelectronics from Nanoparticles” of the University ofDuisberg-Essen, which are both sponsored by the German ResearchFoundation (DFG).

“Our goals for the development of nanotechnological solutionsfor future electronics applications are so ambitious that we can onlyreach them together,” stressed Dr. Harald Schmidt, head of CreavisTechnologies & Innovation, in his welcome address. “Our objective isto forge the optimal link between science and industry, so that newscientific developments can be rapidly converted into new products,“explained Dr. Ralf Anselmann, head of the Nanotronics Science-to-Business Center.

The annual Nanotronics Summer School, a key component ofEvonik’s science-to-business concept, helps promote a fast and com-prehensive exchange of experience and information within the Nano-tronics Science-to-Business Center cooperation network. As a placewhere experts from industry and scientists from a variety of researchinstitutes can conduct an open exchange on current research results,the Nanotronics Summer School and the partnership network it isbased on are unique in the German research landscape.

The workshop was set up like a scientific symposium: The 27presentations covered such topics as the optical properties of siliconquantum dots, conduction mechanisms and structural elements ofnanoparticulate semiconductor layers, improving the conductivity ofITO nanoparticle coatings on polymer substrates, and the processingof nanoscale particles to printed layers. Another highlight of the Sum-mer School was two poster sessions devoted to an in-depth discussionof joint research activities, which also allowed project participants tobecome better acquainted.

In the Nanotronics Science-to-Business Center, Creavis workswith scientists and internationally renowned universities, and coop-erates with two graduate colleges sponsored by the German ResearchFoundation. The project is funded by the State of North Rhine-West-phalia, and co-financed by the European Union. Thanks to the part-nership, the company benefits from an immediate transfer of top re-search, and young scientists from a better understanding of industrialpractice.

Evonik’s Feed Additives Business Unit is expanding the capacity of itsL-threonine facility in Kaba, Hungary, to 20,000 metric tons per year.In addition to the capacity enlargement, the company will upgradeproduction technology and process automation, as well as productdesign, to optimize plant efficiency further. Operated by the subsidiaryEvonik Agroferm, the plant is scheduled to go on stream by the end ofthis year.

“Right from the beginning, in spring 2004, when Evonik acquiredthe Agroferm site, it was our intention to transform the former lysineproduction into a state-of-the-art L-threonine plant,” Dr. Hubert

Wennemer, president of Feed Additives, explained. “This investmentrepresents another cornerstone in our amino acid growth strategy,”Wennemer continued.

“Relative to the capital outlay for a greenfield plant of that size, thespecific investment cost at Kaba is significantly lower. This cost bene-fit combined with the fermentation expertise and skills of our Hun-garian workforce give Evonik a sustainable competitive advantage,”Sigmar Eisele, president of Evonik Agroferm, said.

“Nowadays, Europe accounts for over 50 percent of the globalthreonine market and provides further growth potential, especially in

Creavis discussed resultsfrom the projects ofEvonik’s NanotronicsScience-to-BusinessCenter in Marl withabout 80 universityscientists

+++ Creavis’ Nanotronics Summer School Links Science and Industry

+++ Threonine Facility Being Expanded in Hungary


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respond in a flexible manner to increasing customer demand. Hence,the company has the technical capability for de-bottlenecking its twothreonine production sites further.

L-threonine and L-tryptophan are protein building blocks. They areessential in today’s nutritional concepts for balancing the amino acidlevels in animal feeds and for optimizing livestock production whiledecreasing nitrogen excretion, and thereby reducing the environmen-tal impact of livestock farming.

Evonik’s Kaba, Hungary, site, wherethreonine production is being expanded

Dr. Daniel J. Ostgard of Evonik Industrieswill receive the renowned Raney Award inrecognition of his outstanding work in thefield of heterogeneous catalysis. The cata-lysis researcher is receiving this award forthe development of highly selectivepowder and fixed-bed nickel catalysts usedin industrial hydrogenation processes. TheRaney Award is given out every two yearsby the Organic Reactions Catalysis Society(ORCS) to scientists who have made an im-portant contribution to catalyst technologyin organic synthesis. Ostgard will acceptthe award in March 2008 during the ORCSmeeting in Richmond, Virginia, USA. “We

are very proud of this honor,” said Dr. Hans-Josef Ritzert, head ofEvonik’s Catalysts Business Line. “It underscores not only the sci-entific quality of our research, but its importance for efficient industrialsystems.”

Ostgard has worked for Evonik Industries since 1991 – first in theUnited States and then, since 1998, in Germany. One of the primaryfocuses of his group’s research has been activated metal catalysts.Some of the group’s accomplishments include catalysts that can beused for the complete hydrogenation of nitriles to primary amines.Possible applications include the nitrile hydrogenation that occurs

during Vitamin B2 synthesis and the selective hydrogenation of unsat-urated fatty nitriles to their corresponding unsaturated amines that areused for the production of surfactants and emulsifiers. Ostgard’sgroup has also elucidated the mechanism for the hydrogenating sug-ars such as fructose and glucose. These reactions produce sugar sub-stitutes such as sorbitol or mannitol, which are suitable for use by dia-betics. Dr. Ostgard has used his catalyst expertise since 2006 in theMarketing and Business Development unit of the Catalysts BusinessLine for acquiring new business opportunities.

The ORCS was established in 1975 as a discussion forum forapplied catalysis research, with a focus on organic synthesis. Its mem-bers include both university and industrial researchers from specialtychemicals, fine chemicals, and pharmaceuticals companies. The or-ganization has given out the Raney Award, which is sponsored by theAmerican company W.R. Grace & Co., since 1992. The name of theaward honors the American engineer Murray Raney, who discoveredthe nickel catalyst named after him in 1926. Raney-type nickel cata-lysts are commonly used for the transformation of organic compoundson an industrial scale, especially for the hydrogenation of unsaturatedcompounds.

Evonik is a leading supplier of catalytic system solutions. It offersan extensive range of homogeneous and heterogeneous catalystsfrom a single source, as well as an all-inclusive package of services forcustomers in the life sciences, fine chemicals, industrial chemicals,chemical intermediates, and polymers segments.

+++ Catalysis Research: Evonik Employees Receive Renowned Raney Award

the Eastern area. Additionally, the relative importance of Asia and LatinAmerica is expected to rise overproportionally in the coming years,”Dr. Thomas Kaufmann, vice president of Marketing, explained.

The Kaba site is Evonik’s second state-of-the-art threonine pro-duction facility in Europe, bringing the company’s total capacity to40,000 metric tons per year. The new threonine production line alsofrees up fermentation capacity to be used for production of trypto-phan and other amino acids. This modular concept allows Evonik to


Tissue engineering offers the opportunity of cultivating viable cells of an organism in vitro and replacing damaged tissue, such as skin, with implants made of autologous cells. The generation ofcomplex organic tissue, however, is still in its early stages. Now, researchers at the Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB) have succeeded in producing an artificialliver. This is not only a precursor of future implants: The laboratory-grown organoid tissues also offer a promising method for testing newly developed active ingredients on human tissue.

T I S S U E E N G I N E E R I N G

Conquering New Territory with

Figure 1Collagen carrier scaffoldwith conserved tubularstructures (vascularizedmatrix) for the in vitro pro-duction of human tissues filled with the functionalequivalent of blood vessels.At the Fraunhofer Institutefor Interfacial Engineeringand Biotechnology inStuttgart, this matrix is usedas a substrate for endog-enous human cells for theproduction of artificial tissues and organs

Figure 2 Bioreactor with vascularized matrix for in vitrogeneration of complex human tissues. The gener-ated tissue is supplied with nutrients and oxygenthrough an artery, and the metabolites are purgedthrough a vein. The system thus reflects the smallest unit of human tissue with a functionalblood vessel network


B I O T E C H N O L O G Y

27

PROF. DR. HEIKE MERTSCHING

longside stem cell therapy, which has been in use fordecades, tissue engineering has recently become anestablished methodology within regenerative medi-cine. Compared to proven reconstruction of skin and

cartilage, the cultivation of complex organic tissue that dependson blood supply is still in its infancy. Now, with the help of a newprocess, scientists have succeeded in opening up a new dimen-sion in tissue engineering.

To reproduce 3D tissue models with blood vessel supply, re-searchers at the Fraunhofer Institute for Interfacial Engineeringand Biotechnology (IGB) used parts of the small intestine of apig, which they isolated with an artery for the blood supply anda vein for discharge of the bloodstream (s. Fig. 2) by means of acirculating pump.

To create an artificial liver from human tissue, all of the ani-mal cells of the pig intestine first had to be removed. To do this,the animal organ was put into a bath, in which the intestinal cellswere selectively ruptured by a high osmotic pressure differ-ence. The fragments were removed by rinsing with a chelatingagent. This left a collagen matrix, in which the branched net-work of the vascular system was conserved down to the mostdelicate capillaries (s. Fig. 1).

IGB researchers then streamed a nutrient solution enrichedwith human endothelial cells through this network by means ofa circulation pump. In this procedure, the interior sides of theformer blood vessels are lined – just like the living model – withthe endothelial cells. Signal molecules on the surface of the vas-cular structure ensure adhesion of the cells. The method, whichis universally applicable no matter the genus, produces artificialtissue with a functional network of blood vessels that scientistscall a 3D vascular tissue model.

A computer controls the vital functions of the artificial liver

This model can now be equipped with the cells of a variety of tis-sues and organs. In addition to the endothelial cells of the artifi-cial bloodstream, IGB researchers introduced hepatocytes intothe former intestinal cavity, and within two weeks were able togrow liver-like tissue ex vivo.

The artificial blood circulation can keep this tissue “alive” inthe bioreactor for weeks. In addition, a computer-controlled envi-ronment was created for the artificial liver that recreated natur-al living conditions as closely as possible.

In the human body, hepatocytes are responsible for numer-ous transformations, with the most important of these beingdetoxification. Because the liver model and its added hepatocytesworks, in principle, like a human organ, it opens the opportunityof studying the toxicity of new active ingredients as well as nano-scale materials. Currently, a trachea model is used to test the ex-tent to which nanoparticles are absorbed through the respirato-ry tract organ and circulated in the blood. In subsequent >>>

Artificial Organs

A


tests, researchers can then explain how these particles are latermetabolized in the liver. The artificial liver can even help deter-mine whether long-term effects will occur and what impact anactive ingredient will have when it is administered multipletimes. Long-term tests for these applications are currentlyunderway at IGB.

Better results without animal testing

The strongest argument for the use of artificial liver in pharma-ceutical research is the fact that it is based on human cells. Suchan approach avoids the occasional lack of reproducibility of theresults of animal tests. On the other hand, the model also givesus the opportunity to effectively reduce the number of previ-ously unavoidable animal tests. Last, the process is also suitable,in principle, for growing a complete organ for transplantation inthe future. Compared to transplants of foreign organs, trans-plants like these, made of endogenous cells, would not be reject-ed by the immune system. This option is still somewhat “pie-in-the-sky” – the time-consuming authorization process alonewould take about five years.

Without doubt, the test system marks an important milestonefor pharmaceutical research in its ability to identify toxic or in-effective substances in an early phase of the development of ac-tive ingredients. Researchers also hope to be able to improvetheir understanding of the cell processes responsible for theoccurrence of tumors. Additionally, three-dimensional test tissueoffers an opportunity to accelerate the development of tumortherapeutics.

Chemotherapy is a treatment particularly prone to succeed-ing or failing based on individual differences. To improve con-trol over these individual imponderables, IGB researchers planto first grow a matrix tumor using tumor cells from patients,then treat the tumor with various chemotherapeutic agents toselect the best treatment option for the patient.

Other projects planned by the Institute cover all of the hu-man body’s “gateways” for the intake of active ingredients.These include an artificial intestinal model for such studies asthe mechanism of drug absorption, also in connection with ad-vanced drug delivery systems. Another project aims to depict avascularized full-thickness skin model, which can be used tostudy the transport of active ingredients from the epidermis tothe subcutis. For their part, trachea models should offer insightinto the absorption of active ingredients through the mucousmembrane of the nose and trachea. The findings of these studiescould pave the way for development of patient-friendly forms ofdrug administration, including nasal sprays and inhalers. ●

PROF. DR. HEIKE MERTSCHINGBiologist Heike Mertsching has beenhead of the Cell Systems department at the Fraunhofer Institute for InterfacialEngineering and Biotechnology inStuttgart since 1994.


Figure 3 Bioartificial vascu-larized liver tissue,produced in thePC-controlled bioreactor system(s. Fig. 2) ofFraunhofer IGB



DR. ANDREAS KARAU

At the beginning of 2005, Evonik’s ExclusiveSynthesis & Catalysts Business Unit made a coura-geous decision: Its French subsidiary Rexim, theworld’s third-largest supplier of pharmaceutical

amino acids, would completely change its production from anextractive process based on animal raw materials to fermenta-tion. The first work on process development had begun an entireyear before that. So after two and a half years in development,Rexim used the new process to produce its first ten metric tonsof the amino acid L-proline in bioreactors in May 2006. Thenew key technology is now fermentation, in which the desiredamino acids are manufactured from microorganisms. Suchrapid success would not have been possible without the widevariety of Evonik units that provided their expertise to assistwith the conversion, including the Exclusive Synthesis &Catalysts and Feed Additives Business Units, as well as Creavisand the ProFerm Project House, which has now successfullyconcluded (s. elements18, p. 12 ff).

Amino acids are a primary component of infusions, are usedas chiral compounds in the pharmaceutical industry, and arealso used in many cosmetic products, as well as in sports andwellness nutrition. Manufacturing processes based on animalraw materials have become controversial in the wake of BSE andother animal diseases. Despite the fact that it is scientificallyproven to be safe, acceptance of animal-based starting materialsfor obtaining pharmaceutical amino acids has dropped. Anotherimportant factor is that extraction always involves coproduction,which means that complete participation in the market growth

of specialty amino acids was limited. With this new fermenta-tion technology, Evonik Industries has now created a future-oriented platform for operating fast, efficiently, and with sustain-able responsibility in this attractive market. As early as summer2007, Rexim had successfully validated large-scale fermenta-tive production of two additional amino acids, L-valine andL-isoleucine. Regular production is scheduled to commence inearly 2008. ●

B I O T E C H N O L O G Y

F R O M E X T R A C T I O N T O F E R M E N TAT I O N

ADR. ANDREAS KARAUAndreas Karau is responsible forresearch, development, and quality assurance at the French subsidiary Rexim located in Ham. Previously, he headed the ProFerm Project House,which has since concluded its work.


New Business Prospects for Specialty Amino Acids


In September, Evonik Industries held the groundbreaking ceremonyfor the newly integrated production plant for the manufacture ofmethyl methacrylates (MMA) and methacrylate specialties in theShanghai Chemical Industry Park (SCIP). At a volume of € 250 million,the integrated production plant represents the second-largest singleinvestment ever made by Evonik’s Chemicals Business Area. “Withthis production plant, we are laying the groundwork for participationin what is for us a highly attractive growth market. This investmentwill also consolidate our position as a worldwide leading manufacturerof methacrylates,” emphasized Dr. Klaus Engel, member of the Man-agement Board of Evonik Industries with responsibility for the Chem-icals Business Area.

The world-scale facility is scheduled to come onstream in mid-2009. The integrated MMA production will include, in addition to anannual capacity of about 100,000 metric tons of MMA, productionplants for methacrylic acid, butyl methacrylate, and PMMA moldingcompounds. This will mark the creation of a network, unrivaled andunique in the world, for supplying customers in optoelectronics, thepaint and adhesives industry, and in automobile manufacture.

The integrated production complex will be built on Evonik’s mul-tiuser site SCIP, where the Group has been operating a polyester plantand a colorants plant since June 2006, and where a polycondensationplant for special polymers and a compounding plant will come onstre-am next year. Engel stressed: “China plays a central role for ourgrowth strategy in Asia. Here we must be present on site with ourproduction plants. For this reason, we’ll continue expanding our mul-tiuser site in China.”

The new production plant for thermoplastic methacrylate resins isscheduled to commence operation in the second half of 2009. Theplant will be connected downstream of the integrated MMA facility.“With this plant we’re significantly increasing our worldwide capaci-ties for thermoplastic methacrylate resins,” said Dr. Manfred Spindler,member of the managing board of Evonik Degussa GmbH. He alsostated that, in thermoplastic methacrylate resins, the Chinese markethas the greatest growth potential worldwide. “And our new plant willput us right in the middle of this market.”


Evonik Industries started up a new production facility for PMMA(polymethyl methacrylate) molding compounds in Taichung, Taiwan,together with its joint venture partner Forhouse Corporation. Evonikholds a 51 percent share and Forhouse a 49 percent share in the jointventure Degussa Forhouse Optical Polymers Corporation, launchedin January 2006. The new plant manufactures high-quality PMMAfor optical applications in flat panel displays.

“Global demand for our high-quality PMMA molding com-pounds is set to rise significantly in the next few years,” said GregorHetzke, president of Evonik’s Methacrylates Business Unit. “The mar-ket for liquid-crystal flat panel displays is currently expanding at anannual rate of more than ten percent. The new production facilityenables us to serve this growing market from our local site.”

The plant will have an initial annual capacity of some 40,000metric tons and is designed for “over-the-fence” production. Apartfrom PMMA manufacture, the further processing of lighting modules(backlight units) for flat panel displays will also be located at this site.The integrated supply chain ensures the continuous supply of the ultra-high-purity optical-grade material to customers. The PLEXIGLAS®

molding compound used to manufacture optical light guides in TFTLCD (thin film transistor liquid crystal display) flat panel displays has tomeet the most stringent quality requirements to enable perfect illumi-nation of the displays.

The joint venture unites both partners’ core competencies.Evonik Industries is a leading global manufacturer of PMMA molding

compounds, with its broad product portfolio for all extrusion andinjection molding applications. Forhouse, Evonik’s Taiwanese part-ner, is one of the leading companies in its field and possesses substan-tial expertise in manufacturing and developing lighting modules forflat panel displays. It operates several production facilities in Taiwanand China. In 2006, Forhouse generated sales of some € 492 millionwith about 6,000 employees. In their joint venture, Evonik andForhouse are not only cooperating in their existing business, but arealso developing new products.

Taichung, Taiwan:Evonik’s new production facility for PMMA moldingcompounds

+++ PMMA Molding Compounds for Flat Panel Displays: New Plant Comes Onstream in Taiwan

+++ Groundbreaking Ceremony: New Production Plant for Methacrylates in Shanghai

Laying the foundation stone for the new integratedplant in Shanghai. Representing Evonik were Gregor Hetzke (head of Methacrylates, right), Dr. Michael Müller Hennig (2nd from right, head ofSpecialty Acrylics), Dr. Dahai Yu (3rd from right,Regional President of Evonik Degussa GreaterChina), Project Manager Dr. Claas Klasen (4th fromright),Dr. Manfred Spindler (5th from right, memberof the Management Board of Evonik Degussa GmbH),as well as the deputy chairman and chairman, respectively, of Evonik’s Management Board, Dr. Alfred Oberholz (6th from right) and Dr. Klaus Engel (7th from right)


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For more than € 10 million, Evonik Industries has enlarged itsresearch and development (R&D) center in Shanghai. As one of thelargest R&D centers ever established by a multinational company inShanghai, the new R&D center has a total of 25,000 square meters ofspace, housing state-of-the-art laboratories for research and develop-ment, application technology, and technical service. The investmentincluded the construction of a pilot facility for polymer engineering ina four-story building with a footprint of 1,250 square meters.

The former Shanghai R&D center, in which Evonik invested € 12million, was inaugurated in April 2004. The expansion provides,among other things, a regional hub for sales, marketing, technicalservices, R&D, and the service platform for customers in China andother countries in the Asia-Pacific region.

“Our enlarged R&D center will help us strengthen the interfacebetween the various business units and customers, universities, andresearch institutes in China and provide customers with tailor-madesolutions and our high-quality products. Our center will also be theheadquarters for our marketing and sales activities in China, as well asthe principle site for Evonik’s Chemicals Business Area in this region,”said Dr. Dahai Yu, regional president of Evonik Degussa Greater China.“The expansion of our R&D center marks yet another milestone forour China efforts. We expect sales in the Greater China Region to reach€ 1 billion by 2009.” In the years to come, and in its Chemicals Busi-ness Area, Evonik plans to invest some € 100 million annually in Chinaalone, thereby underscoring its firm commitment in this growth regioneven further.

Evonik Industries and Netherlands-based The Silicon Mine (TSM)Sittard-Geleen are planning to build the first integrated productionfacility for solar silicon in the Netherlands. For this purpose, the twopartners recently signed a letter of intent. In this integrated produc-tion network, Evonik’s Chemicals Business Area will manufactureSiridion® chlorosilanes, from which TSM will produce high-puritysolar silicon for the photovoltaics industry. Evonik will invest a highdouble-digit million euro amount.

“We see solar silicon as a large market with growth over the nextfew years. In the midterm, we aim to take hundreds of millions of eu-ros in order to massively expand our good position in this attractivemarket,” says Dr. Klaus Engel, member of the management board ofEvonik Industries AG and responsible for the Chemicals BusinessArea.

The integrated facility is being built at the DSM site in the munici-pality of Sittard-Geleen in the Limburg province, one of the mostimportant industrial zones in the Netherlands. At the site, Evonik

Industries produces its high-purity Siridion® chlorosilanes, which areconverted by TSM into high-purity solar silicon by means of the well-proven Siemens deposition process: “The synergies of optimizedintegrated production between the partners Evonik Industries andTSM at one of Europe’s largest chemical sites form the basis for thesuccess of the project,” explains Dr. Dietmar Wewers, head ofEvonik’s Silanes Business Line.

Creating at least 400 jobs, TSM is planning an annual productionof 3,750 metric tons of high-purity solar silicon at the site in Sittard-Geleen: “That corresponds to five percent of the world market vol-ume forecast for 2010,” underlines Gosse Boxhoorn, chairman of themanagement board of TSM, adding that annual production capacitycould be increased in the long term even to 14,000 metric tons of solarsilicon.

Evonik Industries is the world’s largest producer of high-puritychlorosilanes. These are raw materials in the production of solar sili-con, which is itself used to produce solar wafers. The photovoltaics in-dustry then processes these wafers into solar cells and modules.

Evonik Industries has been successfully involved in the boomingphotovoltaics market for several years. In April this year, Evonik con-cluded an agreement with the French company Silicium de Provence(Silpro) for a similar integrated production of 4,000 metric tons peryear of solar silicon. The following month it signed jointly with PVSilicon, Erfurt, a long-term supply agreement to provide the 1,800-metric-ton solar silicon production facility currently under constructionin Bitterfeld with Siridion® chlorosilanes.

As early as 2002, the company established, with SolarWorld AGof Bonn, the joint venture Joint Solar Silicon GmbH & Co. KG head-quartered in Freiberg, Saxony. It will produce 850 metric tons peryear of solar silicon from monosilane at Evonik’s Rheinfelden site.

+++ R&D Center Expanded in Shanghai

+++ Evonik and TSM Plan Construction of an Integrated Solar Silicon Production Facility

Raw silicon is the startingmaterial for Evonik’sSiridion® chlorsilanes, from which TSM producesultra-pure solar silicon for the photovoltaics industry


A new emulsion technology from Evonik’sCare & Surface SpecialtiesBusiness Unit allows easy manufacturing and processing of low-viscosityoil-in-water nanoemulsionsthat are free from emulsifiersbased on polyethylene glycol (PEG). Such blendsare highly attractive forthe growing market forimpregnating emulsions formoisturized tissue. Evonik scientists have transferred the advantage of easy processing to classic emulsions.

... by Simple Dilution N A N O E M U L S I O N S F O R P E G - F R E E C O S M E T I C S . . .


I N T E R F A C I A L T E C H N O L O G I E S

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DR. JÜRGEN MEYER

il-in-water emulsions (O/W emulsions) play animportant role in cosmetics: They are fundamentalto the formulation of such products as body lotions,skin creams, and sunscreens. Another relatively

recent but fast-growing field of application is emulsion-basedwet wipes for such applications as baby care and make-upremoval. The key components in these products are low-visco-sity O/W emulsions with good storage stability. Classic emul-sions have typical particle radii of between 0.5 and10 micrometers which causes their typical whiteappearance, and usually show viscosities of over1,000 mPas. They are kinetically stable, and can bemanufactured with the help of a homogenizer. Be-cause their particles are relatively large, however,comparable low-viscosity systems are unstableand cream up.

Alternatively, O/W microemulsions are easyto produce because of their thermodynamic sta-bility. They are translucent, and their typical parti-cle radii range between ten and 40 nanometers.Microemulsions form spontaneously upon mixing,and the order in which the components are addedmakes no difference. However, microemulsion for-mation usually requires large quantities of emulsi-fiers and surfactants.

In terms of their properties, nanoemulsions arepositioned between microemulsions and traditio-nal emulsions. Their typical particle radii rangebetween 30 and 100 nanometers which causestheir typical blue-shining appearance. At thesesmall particle sizes, the Brownian motion preventscreaming, and as a result nanoemulsions oftenhave a long-term good stability. Like classic emul-sions, nanoemulsions are kinetically stable. They are typicallynot easy to produce as they require either high-pressure homo-genizers or very specific manufacturing processes.

The scientists from Evonik’s Care & Surface SpecialtiesBusiness Unit have now overcome this disadvantage with thedevelopment of a low-energy emulsion process for the manu-facturing of nanoemulsions. In this process, a phase with extreme-ly low surface tension is passed. In this phase, the transitionalphase inversion occurs as the affinity of the emulsifier towardsthe oil and water phase changes continuously. To put it in graphicterms, the curvature of the surface changes from W/O (concave)to O/W (convex) in this process. As it changes, the emulsiongoes through a microemulsion-like phase in which the surface isnot curved.

The conventional process for manufacturing finely dis-persed O/W emulsions with a transitional phase inversion is thePIT method (Phase Inversion Temperature method), in whichthe phase transition is obtained by cooling. O/W nanoemulsionsmanufactured by this method are long-term stable and are usedfor a number of cosmetic applications (e. g. wet wipes, sprayableemulsions). PIT emulsions utilize the temperature-dependenthydrophilicity of the ethoxylated emulsifiers.

with Water

OWith the PIT method, the phase inversion temperature method, the affinity of the emulsifierfor the two phases changes at the oil and water interface, depending on the temperature. When a W/O emulsion is cooled, a transitional phase inversion occurs that results in low-viscosity, finely-dispersed O/W nanoemulsions with good storage stability

Wanted: PEG-free alternatives to PIT emulsions

The use of ethoxylated emulsifiers, however, is seen more andmore as a disadvantage. Because consumers increasingly prefernatural ingredients in cosmetics, the industry is extremely in-terested in PEG-free emulsions. And this is just what Evonik hasnow made possible: the manufacture of nanoemulsions withouthomogenizers, without energy input for heating/cooling steps,and without ethoxylates. An oil phase based on this new technol-ogy platform typically consists of three components: PEG-freeemulsifiers (ten to 30 percent), cosmetic oils (50 to 90 percent),and cosurfactants (one to 20 percent). Cosurfactants are surface-active. However, unlike surfactants, they do not form micellesin water, and therefore do not tend to self-aggregate. >>>

T [ºC]

Concentration emulsifiers

80 ºC

RT

PIT

W/Oemulsions

O/Wemulsions

PIT emulsion(kinetically stable

nanoemulsion)

1φ3φ

2φ

2φ

μE region

sume that the water-solubility of the phenoxyethanolis decisive for the occurrence of a microemulsion-like phase: With increasing water concentration, thecosurfactant increasingly migrates out of the surfacefilm and into the water phase, which assists the phaseinversion. The phase inversion is also promoted by aco-emulsifier, such as dilauryl citrate, that becomesmore hydrophilic with increasing water concentra-tion.

Following the successful development of suchO/W nanoemulsions, Evonik’s scientists wonderedwhat they could transfer to the formulation of classicemulsions. In the end, they were able to develop PEG-free emulsifier that requires no heating or homog-enizer. For this emulsifier they used a mixture ofpolyglyceryl-4-laurate and dilauryl citrate, which

had been developed for PIC emulsion systems and has self-emulsifying properties. This mixture is pasty, however, and tooexpensive for typical applications. Consequently, they combinedthis highly active mixture with the liquid basic emulsifier sorbi-tan laurate. Marketed as TEGO® Care LTP, this new O/W emul-sifier mixture can be cold-processed, and allows simple and cost-effective production of cosmetic products in the form of sprays,lotions, and creams. ●


If water is added to this kind of liquid and clear oil phase, amicroemulsion-like phase is passed and a low-viscosity O/Wnanoemulsion with good long-term stability is obtained. Thefirst of Evonik’s products based on this technology are TEGO®

Wipe DE and TEGO® Wipe DE PF, which are for the simple man-ufacturing of impregnating emulsions for cosmetic wet wipes.

In their tests, Evonik’s scientists were able to determine thatthe viscosity of the TEGO® Wipe DE system depends heavily onthe water content. In the microemulsion-like phase, there is asignificant reduction in viscosity, which indicates extremelylow interfacial tension at this point. Similar to the PIT emulsionsystem, this kind of minimum viscosity is typical for the point ofphase inversion from W/O to O/W. Because this inversionpoint occurs at a certain water concentration, the Care & SurfaceSpecialties Business Unit calls the new process a phase inversionconcentration technology. These PIC emulsion systems requireno stirring or heating. Even the order in which the oil and waterare added has no impact on the result. The emulsion mixtureand cosurfactant content, however, must be precisely adjustedwith the oil phase to be emulsified.

In the TEGO® Wipe DE system, the surface-active phenoxy-ethanol, which is often used as a preservative in the cosmeticsindustry, plays the role of the cosurfactant. The researchers as-

DR. JÜRGEN MEYERIn Evonik’s Care & Surface SpecialtiesBusiness Unit, Jürgen Meyer is re-sponsible for the application technologylaboratory in the Personal Care Leave-On unit, which focuses on products thatstay on the skin. Most of his work in-volves the development of new rawmaterials, such as emulsifiers and emol-lients (cosmetic oils), development ofnew formulation ideas for cosmeticleave-on applications, and managementof customer-related projects.

+49 201 173-1621, [email protected]

Phase behavior of the TEGO® Wipe DE system, depending on the water content, at 20 °C(68 °F). At a water content between 35 and 70 percent, the phase transition from a W/Oemulsion to an O/W emulsion occurs. The pronounced viscosity minimum indicates that aphase with extremely low interfacial tension is passed

■■ Conductivity ■■ Viscosity

Conductivity [μS/cm] Viscosity [mPas]

The role of the cosurfactant in PIC emulsions: The solubility of the cosurfactant presumablyensures that, with increasing water concentration, the cosurfactant increasingly migrates fromthe surface film into the aqueous phase, thereby assisting the phase inversion

Simple manufacture of nanoemulsions – for example, for moisturized tissues: Add water to the clear oil phase of the TEGO®

Wipe DE system (left), and following a microemulsion-like phase(middle), a low-viscosity O/W nanoemulsion with long-term stability forms (right)

Weight % H2O

600

550

500

450

400

350

300

250

200

150

100

50

0

120

100

80

60

40

20

00 20 40 60 80 100

Bicontinous structure

Clearsolution

W/Oemulsion

Microemulsion-like phase

0/Wemulsion



PROF. DR. REINHARD STREY

cientists have been experimenting with emulsions forimproving fuel combustion since the 1970s and 1980s.These classic emulsions proved problematic, however,because of their thermodynamic instability and ten-

dency to separate. In addition, the water-oil ratio is not easy toincrease after the emulsion is created. Microemulsions, whosethermodynamic condition regulates spontaneously, offer a wayout of this dilemma. The typical microemulsion has a particlesize of between one and 100 nanometers. Microemulsions reactflexibly to the addition of water or oil.

Microemulsions are thermodynamically stable mixtures ofoil, surfactants, and water. The surfactants form the interfacebetween water and oil, because their hydrophilic portion – thehead – and their hydrophobic portion – the tail – want to pointtoward the water and the oil, respectively, but need differentamounts of space. With non-ionic surfactants, whose heads con-sist primarily of ethylene glycol units or sugars, the water-oil

interface changes from convex to concave when the temperatureincreases. With ionic surfactants, the interface behavior is pre-cisely the opposite.

For this reason, the phase behavior of a microemulsion canbe adjusted through the temperature and the mass portion ofsurfactant relative to the total system. Phenomenologically, themechanisms this is based on are understood and reproducible.Theoretically, they still await a complete explanation. A micro-emulsion becomes temperature-invariant when suitable ionicand non-ionic surfactants are mixed in such a way that the inter-face curve of the system remains constant.

Phase diagrams are useful for describing the behavior ofmicroemulsions. According to the diagram, there are areas for acertain oil-water system in which two phases develop (oil overwater-surfactant, or oil-surfactant over water), and there is anarea in which three phases (water, microemulsion, oil) occur.For each microemulsion, there is an optimal point at which >>>


Water Makes the Diesel CleanMicroemulsions Reduce the Discharge of Pollutants from Engines

Aqueous diesel microemulsions can drastically reduce not only the soot particles but also nitrogen oxides that are generated during combustion. Chemists at the University of Cologne have successfullymanufactured these blends and proven their suitability for everyday use in tests.

S


only one phase forms: the X or fishtail point. Here, the micro-emulsion shows a bicontinual structure, which is also called thesponge structure. Here, the minimal amount of surfactant isrequired and the size of the interface between water and oil isminimal and locally planar.

Diesel engines: putting carbon dioxide and nitrogen oxide emissions to the test

At the University of Cologne, scientists have experimented foryears with these kinds of diesel-and-water microemulsions withthe aim of drastically reducing the environmental damage causedby today’s engines. Soot is an unwanted result of today’s dieselengines and must be removed with expensive particle filters,which actually increase fuel consumption. So while these filtersdo lower soot emissions, they actually cause an increase in theemission of nitrogen oxides.

With a series of measurements at TÜV Essen in conformancewith the European Union End-of-Life Vehicle Directive, as wellas at the Technical University of Trier, the researchers fromCologne proved that the emissions of vehicle engines that weredriven with a water-diesel microemulsion dropped dramatical-ly: the discharge of soot particles by 70 to 90 percent, and of ni-trogen oxides by 30 to 60 percent. In these tests, the researchersalso experimented with various mixtures that were up to 45 per-cent water.

The reason for lower emissions as compared to pure diesel isthat the bicontinual structures of microemulsion presumablycause a more even combustion after the injection of fuel. Withtraditional diesel injection, the soot primarily occurs throughthe relatively slow diffusion of the atmospheric oxygen to thefuel droplets in the combustion chamber. Additionally, free oxy-gen and hydroxy radicals of the water, which are dissociated atthe high temperatures, reduce the soot.

Less nitrogen oxide occurs, in turn, because the high evapo-ration enthalpy of the water lowers the combustion temperature.At the same time, however, the evaporation of the water increasesthe gas pressure, so that the engine can perform at the same

PROF. DR. REINHARD STREYProf. Strey has been a C4 professor for physical chemistry at the University of Cologne since 1996. His R&D activities include boundary layers, colloids, and phase changes. Of special interest within these areas are nanostructure, the thermodynamics and kinetics of liquids, especially of microemulsions, and their use in aqueous fuels, as well as a template for nanofoams.

+49 221 470-4458, [email protected] strey.pc.uni-koeln.de

Figure 1Structure in microemulsions: The structure of the interface between water andoil is influenced by the differing space needs of the heads and tails

Figure 2Phase behavior of a microemulsion system that contains the same amount of oil and water, depending on the temperature and surfactant content γ. An optimal microemulsion forms at the X or fishtail point: It consists of onlyone phase and is characterized by a bicontinual, sponge-like structure

Non-ionic surfactant

WaterWaterWater

HotCold

Hot Cold

Ionic surfactant

OilOilOil

–2

2–

3

T

γφ=0,5

Oil in water

Water in oil

Lα



level despite the lower temperature. When the temperaturedrops, the heat flow also drops proportionately – and with it theheat loss of the engine. The result is up to 20 percent greater ef-ficiency. Since these tests, the scientists have now patented theirwater-diesel microemulsion (DE 103 34 897.2).

Interesting fields of application: block thermoelectric power plants and ships

Car and truck engines are not the only conceivable application.Long-term tests are planned for block thermoelectric powerplants, and the fuel could also be attractive for buses and ships.Eighty percent of soot emissions in the Port of Hamburg, for ex-ample, come from anchored ships whose engines run only forthe sake of generating onboard electricity.


Figure 3Reducing soot emissions: The FSN(Filter Smoke Number) was used to measure the soot discharge,depending on the load and theengine speed n. The diagram shows the characteristic lines formicroemulsions with various watercontent and at constant enginespeeds. At all performance levels,the soot emissions are reduced with increasing water content. Atwater content from 27 percent, the combustion proved to be nearly free from soot with a reduction of over 90 percent

Depending on the application, the microemulsion must notbe premixed, but rather mixed immediately prior to use. TheSkarabäus company, for example, which has developed a pro-cess-controlled emulsifying system for an automobile, is exper-imenting with this “onboard mixing,” which can dose the watercontent depending on the load.

One of the next goals for the scientists from Cologne is mea-suring the emission behavior of engines in day-to-day operation.In the future, they also want to lower the share of surfactantneeded for the microemulsion to below ten percent. Additionalplans include improving the temperature stability. Currently,microemulsions are stable between zero and 95 °C (32 and203 °F). In any case, because of its thermodynamic properties,the water-diesel mixture has no problem with long-term stability:It easily achieved values similar to conventional fuels. ●

Figure 4Reduction of nitrogen oxide emis-sions: The diagram shows the highlyload-dependent emissions of NOxfor two constant engine speeds.With increasing water content, the emissions of microemulsion dropcontinuously, while the presence of small loads results in a higher percentage reduction. Higher watercontent leads to only minimalchanges

■■ Diesel ■■ ME: 9 % H2O ■■ ME: 18 % H2O ■■ ME: 27 % H2O ■■ ME: 36 % H2O ■■ ME: 45 % H2O

Soot emissions at n=1,500 min –1

FSN

Load [Nm]

1.4

1.2

1.0

0.8

0.6

0.4

0.2

00 50 100 150 200 250 300 350

Soot emissions at n=2,100 min –1

FSN

Load [Nm]

1.4

1.2

1.0

0.8

0.6

0.4

0.2

00 50 100 150 200 250 300 350

NOX emissions at n=1,500 min –1

Load [Nm]

1.400

1.200

1.000

0.800

0.600

0.400

0.200

00 50 100 150 200 250 300 350

NOX emissions at n=2,100 min –1

Load [Nm]

1.400

1.200

1.000

0.800

0.600

0.400

0.200

00 50 100 150 200 250 300 350

Designing inorganic particles involves the selective control of key characteristics, such as the size of the primary particles, the size and form of the aggregates, as well as the surface chemistry


DR. PETER NAGLER

norganic particles are all around us – perhaps their mostbeautiful form is the long, white beaches that invite us toswim and relax. Yet not for tourism, but for many industrialapplications inorganic particles are becoming more and more

important. They play an increasingly significant role in nano-technology, for example. The DG Bank predicts that by the year2010, inorganic nanomaterials will account for as much as 28percent of total sales in nanotechnology. This corresponds toover € 60 billion and an enormous € 12 billion in growth since2001 (the market share then was 23 percent). Evonik’s Chem-icals Business Area has a considerable stake in this market. Cur-rently, the company produces roughly 1.7 million metric tons ofinorganic particles per year, and generates sales of about € 1.8billion. This makes it one of the world’s leading manufacturers.The product portfolio includes carbon blacks, precipitated andfumed silicas, and an array of fumed oxides, such as aluminumoxide and titanium oxide, as well as a variety of mixed oxides.Production takes place at 36 sites in 18 countries worldwide.

Inorganic, nanostructured particles can be customizedthrough precise control of key characteristics, first and fore-most of which includes the size of the primary particles and theaggregates they create, their form as well as surface chemistry(the particles have a high specific surface of up to 1,000 squaremeters per gram). There are various methods for producingnanoparticles – including different liquid and gas-phase syn-theses, as well as milling processes. Precipitation processes andflame reactions are used predominantly at Evonik.

When particles are created in a flame reaction, the smallestprimary particles form first, which then grow into larger particlesin the hot zone and, later, into aggregates. By colliding, theseaggregates form even larger agglomerates in the cooler zone ofthe reactor — and all this occurs in the first 100 milliseconds.The reactor selection and manufacturing conditions alone cangenerate different particles, as we can see from the example ofcarbon black. The gas black process, for example, can adjust pri-mary particles to between about 10 and 30 nm in size. With fur-nace carbon black, particles are controllable to between approx-

E V O N I K I S T H E L E A D I N G P R O D U C E R O F I N O R G A N I C P A R T I C L E S

Nearly Endless ApplicaInorganic particles are indispensable for a great many applications. They can be found inrubber compounds, coatings, adhesives, sealants, and plastics, as well as in cosmetics andcatalysts. Thanks to its expertise in customized production of these particles, Evonik is a preferred partner for a host of different industries.

I

The processing of paper (left) to inexpensive high-gloss photo paper (right) is only one of the many application possibilities for customized inorganic particles from Evonik’s Aerosil & Silanes Business Unit

Primary particle size

Aggregate size

Aggregate shape

Surface chemistry


I N O R G A N I C P A R T I C L E D E S I G N

39

imately ten and 80 nm, and with lamp black, between 90 and100 nm. These carbon blacks also differ in terms of their struc-ture – that is, how the aggregates branch – because the primaryparticles are not isolated, as the above diagram shows. For flamehydrolysis of metal halides, Evonik has also developed a processthat allows the production of a great variety of metal oxides.One variable that can be used to create different particles in thisprocess is the dwell time in the reaction zone. The rule of thumb:The longer the dwell time, the larger the aggregates.

New process for particle synthesis

Completely new reaction pathways are opened when gas dynam-ics are introduced to particle synthesis – a method that Evonikand its seven university partners, as well as the German Aero-space Center, are developing and testing as part of a projectsponsored by the German Research Foundation (DFG). The es-sential equipment for this process is two gas jet systems for ul-trafast heating and cooling of the reaction gases. The reactor issupplied with pressurized hot gas. The mixture of base materialand combustible gas is homogeneously ignited behind the firstjet by an ultrasonic burst. Particle genesis and growth then fol-lows. With the same effect, the particle formation is interruptedat the second jet, and the gas is quenched with cold water. This ar-rangement promises several advantages: One is that the processallows very high heating and cooling rates. Another is that itenables high throughput and a homogeneous temperature pro-

file in the reactor. In this way, particle diameters can be selec-tively controlled to produce a narrow particle-size distribution.

Against the backdrop of these synthetic options, Evonik’sChemicals Business Area has an exceptionally wide variety ofinorganic particles that create new functionalities in completelydifferent areas of application. The list of fields is nearly endless:They range from the rubber industry with the main applicationin tires, through sealants and adhesives, paints and coatings,printing inks, ink jet pigments, paper, plastics, cables, fibers,illuminants, plant protection formulations, defoamers, and >>>

tions

Evonik’s newly developed dynamic gas-phase process for producing inorganic particles allows a narrow particle-size distribution with low aggregation

Hot gas supply

PrecursorParticle formation and growth Water supplyInjector

First nozzle Reaction volume Secondnozzle

Quenching


catalysts, all the way to animal feeds, cosmetics, and toothpastes.In car tires, for example, carbon black and silica are used to im-prove abrasion resistance, wet grip, and rolling resistance, whilein other applications they have a positive impact on elasticity,stability, rheology, and conductivity, or impart water re-pellency, transparency, and dispersibility – to name just a few.

Custom-tailored particles like the new Aerosil® type R 9200,a surface and structure-modified fumed silica, have significantlyimproved the scratch resistance of automotive paints. The inor-ganic particles are homogeneously distributed in the surface ofthe paint and, thanks to their hardness, improve resistance tomechanical stresses such as car wash brushes and tree branches.New inorganic particles also make the difference between blackand black in the painting of vehicles – the innovative furnaceblack pigments with a bluish tinge can be dispersed extremelywell, are exceptionally weather resistant, and thus are particular-ly well-equipped to meet the needs of the automotive industry.

No high-performance chips without polishing slurries

Microchips are becoming increasingly smaller and more com-plex. A vital requirement for the structures, which are now partof the nanocosmos, is chemical-mechanical planarization(CMP). This process must be applied several times per wafer, andinvolves the use of slurries made of ceroxide (AdNano® Ceria),silicone oxide (Aerosil® 90) and aluminum oxide (Aeroxide®

ALU C) for various conducting and insulating layers. Studieshave shown that when polishing liquids are not optimized, de-fect rates resulting from such factors as residual ceroxide on theprocessing surface are high, and can be reliably avoided byusing Evonik’s product.

The product INDISPRON® D 110, which contains a modifiedsilica, is opening up a completely new application. It has longbeen known that silicas have a drying effect on insects. Becausethey are easy to apply as an aqueous dispersion, they offer a simpleand highly effective opportunity to fight such widespread para-sites as the red fowl mite in layer hen husbandry. Suitable sprayequipment is used to apply the milky, yoghurt-like liquid to allsurfaces of the housing – a method that has great advantagesover powders in terms of dosing, adhesion and occupationalsafety. The registration to use INDISPRON® as an insecticide isongoing in a number of countries. In Germany, where about 18billion eggs are consumed annually, it has been registered sinceJuly. Evonik promotes its new product with the slogan “Safe foodfrom the stable to the table.”

The potential uses of inorganic particles are nearly unlim-ited: zinc oxide for UV protection; indium tin oxide for trans-parent and antistatic coatings or for IR absorption; Zirconia fortechnical ceramics and wear protection; and MagSilica®, an ironoxide in a matrix made of fumed silicas for resolvable adhesivebonds. Adhesives that contain MagSilica® can be warmed througha magnetic alternating field, and thereby harden far faster thanconventional products. They can also be redissolved, however,through precise heating, which effectively “switches off” theadhesive bond.

Thanks to its expertise in the customized production ofthese particles, Evonik is a preferred partner for a whole host ofdifferent industries. The company also has an excellent basis forexpanding its “particle zoo,” if needed. ●

DR. PETER NAGLERPeter Nagler is head of Research,Development, and ApplicationEngineering in Evonik’s Aerosil & SilanesBusiness Unit.


Aerosil® R 9200, a new surface and structure-modified fumed silica, makesautomotive paints considerably more scratchproof (photo right) and moreresistant to mechanical stresses such as those encountered in a car wash.These properties are based on the homogeneous distribution of inorganicparticles in the surface of the paint (photo below)

Electron micrograph of a surface that was polished with a non-optimized (photo left) and an optimized polishing liquid based on AdNano® Ceria (photo right)



PROF. DR. STEFAN KASKEL

norganic fillers have been used in polymers for decades, espe-cially for improving their mechanical behavior. But differentfillers can also positively influence UV and fire resistance,electrical conductivity, and thermal stability. Nowadays, more

and more fillers also contain nanoparticles to add more function-ality to matrix plastics or to further improve their properties.

While traditional composites with particles in the microme-ter range or agglomerates scatter light and thereby do not lendthemselves to optical applications because of their turbidity,nanoparticles below 100 nanometers (nm) are so small that theyimpart high transparency. In addition to extreme hardness andthermal stability, inorganic particles also give the polymer spe-cial electrical and optical properties.

To produce such materials, scientists need special syntheticpathways not only to create nanoscale particles but to distributethem as aggregate-free and homogeneously in the polymer aspossible. Processes that produce the particles as far as possiblein situ, and integrate them as such into the polymer – while atthe same time preventing them from clustering into larger ag-

gregates and agglomerates – offer great opportunities. A particlesize of below 40 to 50 nm is essential for manufacturing trans-parent nanocomposites. The scatter light intensity also increasessignificantly with the growth in particle size. Displays, light di-odes, and illumination are the primary application opportuni-ties for luminescent nanoparticles and the luminescent nano-composite materials derived from them. Methods for supplyinginorganic nanoparticles and their dispersion in polymers havebeen developed at the Institute for Inorganic Chemistry at theTechnical University of Dresden.

One option is to use microemulsions, which are thermody-namically stable compounds of water, oil, and surfactants –water-in-oil emulsions – in which the size of the water dropletsand, therefore, that of the particles, is controllable over a widerange through the surfactant content.

In a study in Dresden, the method was applied to the manu-facture of composites with bismuth oxide particles as a reddish-brown color pigment. BiOI particles are formed when twoemulsions containing bismuth oxide and iodide ions are >>>


I

I N O R G A N I C N A N O F I L L E R S F O R T R A N S P A R E N T P O LY M E R S

Invisible Helpers for New Functionalities

BaTiO3 nanoparticles

Stabilization of the BaTiO3 structureby carboxylic acid (schematic)

R – CO

OM


mixed together. If the oil phase is replaced by a reactive mono-mer, the entire compound can be polymerized. In this process,the BiOI particles are distributed into the matrix as separatenanoparticles, which results in a highly transparent material.The color can be programmed from light yellow to reddish-brown, depending on the particle size. The method is limitedprimarily because it realizes a low solids content of no morethan two percent. The manufactured composites show a photo-chromatic effect – in other words, UV light can be used to tunethe color from yellow to brown and back again.

Homogeneous distribution of nanoparticlesthrough phase transfer

A second process is phase transfer. Europium-doped yttriumvanadate is an efficient red illuminant used in such products ascolor TVs and displays. Europium is the source of luminescencewithin the yttrium host lattice. Nanoparticles of this compoundcan be dispersed in water and stabilized with citrate. Amines

can be added to achieve a phase transfer to pentane or heptane,and the monomer can be incorporated into this stable phase.

In the actual study, the doped yttrium vanadate was photo-polymerized with lauryl acrylate. Examination of the particlesize distribution in the water and in the polymer showed nearlyidentical values, which provided evidence that there was noaggregation. A larger solids content of up to ten percent can bereached with this method, although higher contents will pro-gressively impair transparency. The method can be used to pro-duce invisible samples, for example, or characteristics that canbe seen only under a UV lamp and, therefore, heighten securityagainst brand piracy.

Monomer coordination also offers an opportunity to createnanocomposites. In one example, zinc acetate dihydrate wasdispersed in ethanol, and was then replaced by polybutanediolmonoacrylate (PBDMA). Control over the size of the ZnO parti-cles is possible at the time BDMA is added to the ethanol-basedZnO dispersion. The process has achieved up to eight weightpercentages of ZnO in the polymer, while preserving high

BiOI nanoparticles

Transmission Electron Microscope

Photchromatic pattern generation in BiOI nanocomposites

Patterning

Luminescent pattern in YVO4: Eu nanocomposites

ZnO/BDMA composite

Distribution of ZnO nanoparticles in the polymer (Transmission Electron Microscopy)


transparency. The ZnO dispersion in BDMA can be polymer-ized directly by UV radiation or heat input. Cross-sectional stud-ies using a transmission electron microscope (TEM) show verygood distribution of the particles in the polymer. After incorpo-ration of the nanoparticles, the mechanical properties, such asthe elasticity module, are significantly improved. Even theembrittlement properties of the matrix plastic are optimized bythe ZnO particles, thanks to the UV protection.

Ferroelectric ceramics are used as fillers for the design of di-electrical components. A typical example is barium titanate,which is incorporated into non-conducting polymers. A fourthprocess, two-phase hydrothermal growth, is used for this appli-cation. First, barium and titanate are dispersed as salts of oleicacid in the oil phase. With caustic soda solution as the mineraliz-er, crystallization occurs at the oil-water interface: The bariumtitanate changes the phase under heat input and is present innanocrystalline form in the oil phase, while sodium oleate formsin the aqueous phase. Polymerization – with polylauryl acrylate,for example – is obtained from the oil phase. Images from a

secondary electron-scanning microscope (SEM), which wereprepared for barium as well as for titanium, reveal the extreme-ly fine dispersion of barium titanate particles in the polymer.The mean value of the particles is 3.6 nm, at a close size distri-bution of only a few nm more or less.

Integration of inorganic nanoparticles into polymers allowsthe properties of both classes of materials to be combined. Theadvantages are mainly twofold: new functionalities and newprocessing methods. In principle, we have a wide selection of in-organic components, as well as polymer matrices, from which tochoose. Producing these materials when higher particle contentis required, however, remains a challenge. Thus far, the workdone in Dresden has fallen under the category of basic research.It would be interesting if the research could now turn towardapplications, such as electroluminescent components. The opti-cal, magnetic, and electric properties are so highly promisingthat further effort would surely prove rewarding. ●


PROF. DR. STEFAN KASKELStefan Kaskel has been Professor forInorganic Chemistry at the TechnicalUniversity of Dresden since 2004.Previously, he worked at the Max PlanckInstitute for Coal Research in Mülheim ander Ruhr. His areas of research are thedesign, synthesis, characterization, andapplications of porous and nanostructuredmaterials with an emphasis on metalorganic frameworks (MOF), mesoporousmaterials, and polymer nanocomposites.

+49 351 4633-4885, [email protected]


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Published byEvonik Degussa GmbHInnovation Management ChemicalsBennigsenplatz 140474 DüsseldorfGermany

Scientific Advisory BoardDr. Norbert FinkeEvonik Degussa GmbHInnovation [email protected]

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