POLYALKYLENE AND POLYARYLENE OXALATES FROM …€¦ · Although occurrence of oxalates is wide in...

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POLYALKYLENE AND POLYARYLENE OXALATES FROM BIORENEWABLE DIOLS VIA ESTER INTERCHANGE

By

JOHN JAIRO GARCIA OCAMPO

A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT

OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2012

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© 2012 John Jairo Garcia Ocampo

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To my father and mother

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ACKNOWLEDGMENTS

I would like to thank the members of my committee: Dr. Wagener, Dr. Smith, and

especially Dr. Miller for their support and ideas during the development of this project.

Of course I also want to thank the University of Florida for the resources, facilities,

professors and their guidance during these years. I have to thank the members of the

Butler Polymer Research Laboratory, my friends and lab mates of the Miller Lab for the

support, and help through this time.

I cannot forget to thank Dr. Fabio Zuluaga, who encouraged me to join UF, I’m

highly grateful with him for encouraging me to look for this unique opportunity to be

here, as well his guidance along my time here.

Finally, I have to thank my parents; their unconditional love and support were keys

of who I am and what I’ve done.

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TABLE OF CONTENTS page

ACKNOWLEDGMENTS .................................................................................................. 4

LIST OF TABLES ............................................................................................................ 7

LIST OF FIGURES .......................................................................................................... 8

LIST OF ABBREVIATIONS ........................................................................................... 14

ABSTRACT ................................................................................................................... 15

CHAPTER

1 MOTIVATION AND TARGETS ............................................................................... 16

1.1 Polymers: Petroleum Based Commodities ........................................................ 16 1.2 Environmental Problematics ............................................................................. 16 1.3 Polymers from Biorenewable Feedstocks ......................................................... 16

2 OXALIC ACID ......................................................................................................... 18

2.1 General Aspects ............................................................................................... 18 2.2 Presence in Nature ........................................................................................... 18 2.3 Synthetic Pathways........................................................................................... 19

3 DIOLS ..................................................................................................................... 20

3.1 Aliphatic Diols ................................................................................................... 20 3.2 Aromatic Diols ................................................................................................... 20

4 POLYOXALATES ................................................................................................... 22

4.1 Background ....................................................................................................... 22 4.2 Applications ...................................................................................................... 22 4.3 Degradability ..................................................................................................... 23 4.4 Polyalkylene Oxalates ....................................................................................... 23

4.4.1 Synthesis and Characterization ............................................................... 24 4.4.2 Effects of Methylene Spacers .................................................................. 26 4.4.3 Conclusions ............................................................................................. 28

4.5 Polyarylene and Copoly(Alkylene-Arylene) Oxalates ........................................ 29 4.5.1 Synthesis and Characterization ............................................................... 30 4.5.2 Effect of the Incorporation of Aromatic Units into the Polymer ................ 31 4.5.3 Degradation ............................................................................................. 32 4.5.4 New Ideas ............................................................................................... 33

4.5.4.1 Copolymers with 1,4-butanediol ..................................................... 33

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4.5.4.2 Polyoxalates based on hydroquinone ............................................ 33 4.5.4.3 Vanillin based diols for polyarylene oxalates .................................. 34

4.5.5 Conclusions ............................................................................................. 35

5 EXPERIMENTAL PROCEDURES .......................................................................... 36

5.1 Molecular Characterization ............................................................................... 36 5.2 Polymerization Procedures ............................................................................... 37 5.3 Synthesis of Aromatic Diol ................................................................................ 42

APPENDIX

A PROTON AND CARBON NMR .............................................................................. 43

B POLYMER DATA .................................................................................................... 65

LIST OF REFERENCES ............................................................................................... 94

BIOGRAPHICAL SKETCH ............................................................................................ 96

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LIST OF TABLES

Table page 1-1 Presence of oxalic acid in vegetables ................................................................. 18

4-1 Polyalkylene oxalates, molecular and thermal properties ................................... 25

4-2 Copoly(alkylene-arylene) oxalates, macromolecular and thermal properties ..... 30

4-3 Degradation of copoly(alkylene-arylene) oxalates .............................................. 33

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LIST OF FIGURES

Figure page 3-1 Resorcinol........................................................................................................... 21

3-2 Hydroquinone ..................................................................................................... 21

4-1 Degradation study of polyoxalate in aqueous solution ........................................ 23

4-2 General reaction of polyoxalates synthesis. ....................................................... 24

4-3 General mechanism for Fisher esterification ...................................................... 25

4-4 Representation of two chains of polybutylene oxalate ........................................ 27

4-5 Melting and glass transition temperatures of polyalkylene oxalates along different number of methylene groups in the backbone ...................................... 27

4-6 Representation of two pairs of chains of polypropylene oxalate and polyneopentylene oxalate ................................................................................... 28

4-7 Resorcinol bis(beta-hydroxyethyl)ether (4.12). ................................................... 29

4-8 1H NMR spectra of polymers 4.9, 4.16 and 4.22 for incorporation calculation .... 31

4-9 Melting temperature of copoly(alkylene-arylene) oxalates. ................................. 31

4-10 Fox equation for random copolymers, where w is weight fraction ...................... 32

4-11 Glass transition temperature of copolymers ....................................................... 32

4-12 Copolymer using 1,4-butanediol as comonomer. ............................................... 33

4-13 Poly resorcinol bis(beta-hydroxyethyl)ether oxalate ........................................... 34

4-14 Vanillin based unsymmetrical diol ....................................................................... 34

4-15 Vanillin based symmetrical diols ......................................................................... 35

5-1 Polymerization device: A hot plate with temperature control, oil bath, flask containing the reagents and connection to a vacuum line through a bump trap.. ................................................................................................................... 37

5-2 Polyprolylene oxalate (4.1) ................................................................................. 38

5-3 Polyneopentylene oxalate (4.2) .......................................................................... 38

5-4 Polybutylene oxalate (4.3) .................................................................................. 38

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5-5 Polypentylene oxalate (4.4) ................................................................................ 39

5-6 Polyhexylene oxalate (4.5) ................................................................................. 39

5-7 Polyheptylene oxalate (4.6) ................................................................................ 39

5-8 Polyoctylene oxalate (4.7) .................................................................................. 39

5-9 Polynonylene oxalate (4.8) ................................................................................. 40

5-10 Polydecylene oxalate (4.9) ................................................................................. 40

5-11 Polyundecylene oxalate (4.10) ........................................................................... 40

5-12 Polydodecylene oxalate (4.11) ........................................................................... 41

5-13 Copolymer (4.17) ................................................................................................ 41

5-14 Poly resorcinol bis(beta-hydroxyethytl)ether oxalate (4.22) ................................ 41

5-15 Synthesis of Resorcinol bis(beta-hydroxyethyl)ether (4.12) ............................... 42

A-1 1H NMR of polymer 4.1 ....................................................................................... 43

A-2 13C NMR of polymer 4.1 ..................................................................................... 43

A-3 1H NMR of polymer 4.2 ....................................................................................... 44

A-4 13C NMR of polymer 4.2 ..................................................................................... 44

A-5 1H NMR of polymer 4.3 ....................................................................................... 45

A-6 13C NMR of polymer 4.3 ..................................................................................... 45

A-7 1H NMR of polymer 4.4 ....................................................................................... 46

A-8 13C NMR of polymer 4.4 ..................................................................................... 46

A-9 1H NMR of polymer 4.5 ....................................................................................... 47

A-10 13C NMR of polymer 4.5 ..................................................................................... 47

A-11 1H NMR of polymer 4.6 ....................................................................................... 48

A-12 13C NMR of polymer 4.6 ..................................................................................... 48

A-13 1H NMR of polymer 4.7 ....................................................................................... 49

A-14 13C NMR of polymer 4.7 ..................................................................................... 49

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A-15 1H NMR of polymer 4.8 ....................................................................................... 50

A-16 13C NMR of polymer 4.8 ..................................................................................... 50

A-17 1H NMR of polymer 4.9 ....................................................................................... 51

A-18 13C NMR of polymer 4.9 ..................................................................................... 51

A-19 1H NMR of polymer 4.10 ..................................................................................... 52

A-20 13C NMR of polymer 4.10 ................................................................................... 52

A-21 1H NMR of polymer 4.11 ..................................................................................... 53

A-22 13C NMR of polymer 4.11 ................................................................................... 53

A-23 1H NMR of compound 4.12 ................................................................................. 54

A-24 13C NMR of compound 4.12 .................................................................................. 54

A-25 1H NMR of polymer 4.13 ..................................................................................... 55

A-26 13C NMR of polymer 4.13 ................................................................................... 55

A-27 1H NMR of polymer 4.14 ..................................................................................... 56

A-28 13C NMR of polymer 4.14 ................................................................................... 56

A-29 1H NMR of polymer 4.15 ..................................................................................... 57

A-30 13C NMR of polymer 4.15 ................................................................................... 57

A-31 1H NMR of polymer 4.16 ..................................................................................... 58

A-32 13C NMR of polymer 4.16 ................................................................................... 58

A-33 1H NMR of polymer 4.17 ..................................................................................... 59

A-34 13C NMR of polymer 4.17 ................................................................................... 59

A-35 1H NMR of polymer 4.18 ..................................................................................... 60

A-36 13C NMR of polymer 4.18 ................................................................................... 60

A-37 1H NMR of polymer 4.19 ..................................................................................... 61

A-38 13C NMR of polymer 4.19 ................................................................................... 61

A-39 1H NMR of polymer 4.20 ..................................................................................... 62

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A-40 13C NMR of polymer 4.20 ................................................................................... 62

A-41 1H NMR of polymer 4.21 ..................................................................................... 63

A-42 13C NMR of polymer 4.21 ................................................................................... 63

A-43 1H NMR of polymer 4.22 ..................................................................................... 64

A-44 13C NMR of polymer 4.22 ................................................................................... 64

B-1 TGA of polypropylene oxalate 4.1 ...................................................................... 65

B-2 DSC of polypropylene oxalate 4.1 ...................................................................... 65

B-3 TGA of polyneopentylene oxalate 4.2 ................................................................. 66

B-4 DSC of polyneopentylene oxalate 4.2 ................................................................ 66

B-5 TGA of polybutylene oxalate 4.3......................................................................... 67

B-6 DSC of polybutylene oxalate 4.3 ........................................................................ 67

B-7 TGA of polypentylene oxalate 4.4 ....................................................................... 68

B-8 DSC of polypentylene oxalate 4.4 ...................................................................... 68

B-9 TGA of polyhexylene oxalate 4.5 ........................................................................ 69

B-10 DSC of polyhexylene oxalate 4.5 ........................................................................ 69

B-11 TGA of poly heptylene oxalate 4.6 ...................................................................... 70

B-12 DSC of polyheptylene oxalate 4.6 ...................................................................... 70

B-13 TGA of polyoctylene oxalate 4.7 ......................................................................... 71

B-14 DSC of polyoctylene oxalate 4.7 ......................................................................... 71

B-15 TGA of polynonylene oxalate 4.8 ........................................................................ 72

B-16 DSC of polynonylene oxalate 4.8 ....................................................................... 72

B-17 TGA of polydecylene oxalate 4.9 ........................................................................ 73

B-18 DSC of polydecylene oxalate 4.9 ........................................................................ 73

B-19 TGA of polyundecylene oxalate 4.10 .................................................................. 74

B-20 DSC of polyundecylene oxalate 4.10 .................................................................. 74

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B-21 TGA of polydodecylene oxalate 4.11 .................................................................. 75

B-22 DSC of polydodecylene oxalate 4.11 .................................................................. 75

B-23 TGA of copolymer 4.13 ....................................................................................... 76

B-24 DSC of copolymer 4.13 ...................................................................................... 76



















B-43 GPC of polyneopentylene oxalate 4.2 ................................................................ 86

B-44 GPC of polypentylene oxalate 4.4 ...................................................................... 86

B-45 GPC of polyhexylene oxalate 4.5 ....................................................................... 87

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B-46 GPC of polyheptylene oxalate 4.6 ...................................................................... 87

B-47 GPC of polyoctylene oxalate 4.7 ........................................................................ 88

B-48 GPC of polynonylene oxalate 4.8 ....................................................................... 88

B-49 GPC of polydecylene oxalate 4.9 ....................................................................... 89

B-50 GPC of polyundecylene oxalate 4.10 ................................................................. 89

B-51 GPC of polydodecylene oxalate 4.11 ................................................................. 90

B-52 GPC of copolymer 4.13 ...................................................................................... 90







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LIST OF ABBREVIATIONS

C Celsius

Cat. Catalyst

Da Dalton

DMSO Dimethyl sulfoxide

DSC Differential Scanning Calorimetry

g Grams

GPC Gel Permeation Chromatography

Hz Hertz

J Joules

mg Milligram

MHz Mega hertz

mL Milliliter

mol Moles

mol% Mole percent

Mw Weight average molecular weight

NMR Nuclear magnetic resonance

N2 Nitrogen gas

PDI Polydispersity index

ppm Parts per million

Tg Glass transition temperature

TGA Thermal gravimetric analysis

THF Tetrahydrofuran

Tm Melting temperature

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Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the

Requirements for the Degree of Master in Science

POLYALKYLENE AND POLYARYLENE OXALATES FROM BIORENEWABLE DIOLS VIA ESTER INTERCHANGE

By

John Jairo Garcia Ocampo

December 2012

Chair: Stephen A. Miller Major: Chemistry

It is difficult to think about a modern world without polymers; they are part of our

lives and serve different purposes making our life somehow easier. However, polymers

are mainly products from petroleum, which is a non-renewable resource. The price

tends to be high and variable, and degradation of many of those polymers is slow in

environmental conditions. Regarding this situation there is an increasing interest in

finding biorenewable resources that could lead to cheaper and more abundant starting

materials for synthesis of these polymers, as well as developing novel biodegradable

polymers to reduce the impact of their disposal in landfills.

Although occurrence of oxalates is wide in nature, few studies have been done

with polymers containing this functional group. Some of these studies have been

related with degradation of polyoxalates indicating the potential biodegradability of these

compounds. In the present work, a methodology to synthesize poly oxalates in melt and

acid catalyzed was developed. The thermal properties of different polyalkylene and

polyarylene oxalates were studied, with special focus in the decanediol and resorcinol

bis(beta-hydroxyethyl)ether as potential biorenewable diols that can provide higher

melting temperature (Tm) and glass transition temperature (Tg) to the polymer.

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CHAPTER 1 MOTIVATION AND TARGETS

1.1 Polymers: Petroleum Based Commodities

Polymer synthesis and applications are some of the hottest topics in scientific

research over the last century, with hundreds of thousands of publications per year in

this area. Their versatility and the relative easiness to synthesize and process them led

to a massive production of consumer goods around the world. The petrochemical

industry is the main source of raw materials of synthetic polymers nowadays.

However, this convenient source implies a problem: petroleum is not a renewable

resource, which means eventually in the future humanity will run out of it. Among other

causes, this uncertainty leads to its unstable price and it is believed that is going to be

higher in the next decades, increasing the prices of these polymers.

1.2 Environmental Problematics

Another concern about most of petroleum based polymers is the environmental

impact in the biosphere. These polymers might take hundreds or thousands of years to

decompose in lands, rivers, or oceans, causing contamination and harming the life of

many species, including ourselves.

Considering this, our group is focused on polymers with high degradability (either

chemical or biological) and/or synthesized from biorenewable resources to diminish the

impact in the environment of the production of plastics in the world.

1.3 Polymers from Biorenewable Feedstocks

There is an increasing interest in finding novel polymers from biorenewable

feedstocks to replace petroleum as raw material as well as finding potential

biodegradable plastics which decompose faster under environmental conditions. Poly

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lactic acid (PLA) is one of the polymers being used; lactic acid is produced by

fermentation of sugars.

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CHAPTER 2 OXALIC ACID

2.1 General Aspects

Also known as ethanedioic acid, oxalic acid is the simplest dicarboxylic acid,

having a formula of C2H2O4. Its molecular weight is 90.04 g/mol. Anhydrous oxalic acid

can be crystallized from glacial acetic acid, is orthorhombic, and the crystals can be

pyramidal or elongated octahedral. It is hygroscopic and the melting point is at 189.5

°C. Oxalic acid sublimes at 157 °C; meanwhile at higher temperatures it may

decompose into CO, CO2, formic acid and water.1

2.2 Presence in Nature

Oxalic acid is present in many vegetables, especially in the cell sap of plants

belonging to the Oxalis and Rumex families as the potassium or calcium salt. Also

species of Penicillium and Aspergillus convert sugar into calcium oxalate with 90%

yields under optimal conditions.1 Oxalic acid is also present in different quantities in

some vegetables as shown in Table 1-1.2

Table 1-1. Presence of oxalic acid in vegetables

Vegetable Concentration (%)

Amaranth 1.09 Beans, snap 0.36 Beet leaves 0.61 Brussels sprouts 0.36 Carrot 0.50 Cassava 1.26 Chives 1.48 Collards 0.45 Garlic 0.36 Lettuce 0.33 Pepper 0.04 Potato 0.05 Purslane 1.31 Radish 0.48 Sweet potato 0.24 Tomato 0.05

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2.3 Synthetic Pathways

Oxalic acid can be obtained by fusion of cellulose matter with NaOH, by oxidation

with HNO3 and also by passing carbon monoxide through concentrated NaOH or

Na2CO3.1 In 1926 Walter Wallace patented a procedure when oxalic acid is produced

by absorption of carbon monoxide in alkali or alkaline solution under heat and pressure

to form sodium formate solution, which was evaporated and heated to form sodium

oxalate, then treated with calcium hydroxide and water to precipitate calcium oxalate,

which was at the end treated with sulfuric acid to obtain finally the oxalic acid.3

Oxidation of glucose or other carbohydrates can also be done using NaOH and HNO3

or air in presence of vanadium pentoxide.4

In the literature there are several papers reporting oxalic esters that can be

produced by the carbonylation of alcohols using Pd (II) complexes.5-8

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CHAPTER 3 DIOLS

3.1 Aliphatic Diols

Aliphatic diols have been used widely to synthesize polyesters, ethyleneglycol

being one of the most popular to produce polyethyleneterephthalate (PET). 1,3-

propanediol can be polymerized with terephthalic acid or dimethyl terephthalate to

produce polytrimethylene terephthalate (PTT) and it has been obtained from

hydroformylation of ethylene oxide to afford 3-hydroxypropionaldehyde and then

hydrogenation of the aldehyde to alcohol. Currently DuPont® has developed a synthetic

way starting with corn syrup and using a genetically modified strain of E.Coli9. Another

way to produce it is by conversion of glycerol using Clostridium diolis bacteria and

Enterobacteriaceae.10

1,4-butanediol is also used to produce elastic fibers and polyurethanes. It has

been processed industrially by reacting acetylene with formaldehyde to form 1,4-

butynediol, which is finally hydrogenated. Genomatica®, a company in San Diego, CA

had genetically modified E. Coli to metabolize sugar into 1,4-butanediol.11,12

1,10-decanediol is a potential green diol that can be obtained from castor oil, a

mixture of fatty acids that contains mostly ricinoleic acid (up to 90%) present in the

castor beans.13,14

3.2 Aromatic Diols

Aromatic diols play an important role in the synthesis of polyesters due the

presence of sp2 hybridized aromatic carbons which provide more rigidity to the polymer

backbone.15

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Resorcinol is an aromatic diol (benzene-1,3-diol) which is currently obtained from

the petrochemical industry, although it could be obtained from distillation of Brazilwood

extract as well. In 1994 the production of resorcinol was estimated to be 30,000 to

35,000 tons. It is used primarily in the rubber industry for tires, reinforced rubber and

high quality wood adhesives. It is also used in the pharmaceutical industry, in the

preparation of dyes, cosmetics, and as a cross-linking agent for neoprene.16

Figure 3-1. Resorcinol

Hydroquinone (benzene-1,4-diol) is another interesting aromatic diol and is an

isomer of resorcinol. It has been synthesized through the cumene process and

hydroxylation of phenol. Frost and coworkers found a benzene-free synthetic pathway

to obtain this diol by oxidation of glucose which is promising in order to obtain

biorenewable aromatic diols.17

Figure 3-2. Hydroquinone

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CHAPTER 4 POLYOXALATES

4.1 Background

Polyoxalates have been studied for many years. Carothers and coworkers

published in 1930 a work involving the synthesis of polyethylene, polypropylene,

polyhexylene and polydecylene oxalate. In the case of polyethylene oxalate, they

mentioned the existence of three forms: a monomer (Tm = 144 °C) with a molecular

weight between 118 and 126 Da., a soluble polymer (Tm = 159 °C) with a molecular

weight about 2400 Da. and an insoluble polymer (Tm = 172 °C) with an unknown but

probably higher molecular weight. Carothers and coworkers also found some fractions

with intermediate melting points which they claimed could be a mixture of these forms

although these fractions were unstable at standard conditions. Polypropylene oxalate

was synthesized from 1,3-propanediol and diethyl oxalate showing a melting

temperature of 86 °C, meanwhile polyhexylene and polydecylene oxalate had melting

temperatures of 66 and 79 °C respectively.18 Recently other research groups have been

studying some properties and possible applications of polyoxalates, including

copolymemerization with other components like azelaic acid19, urethanes20 and

terephthalates21.

4.2 Applications

Because of their degradability, one of the most important applications of

polyoxalates has been in the medicine. In 1977 Coquard et al. obtained a patent for

implantable surgical articles based on polyesters of succinic and oxalic acid and

relatively short diols between 2 and 6 carbon atoms22. In 1978 and 1980 Shalaby et al.

obtained two patents for absorbable coating for sutures using polyalkylene oxalates,

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specifically mixtures of butylene, hexylene, octylene, and dodecylene oxalate.23,24

Starting in the 1980s some studies of novel drug delivery systems for medical purposes

have been focusing on polyoxalates for this purpose as well25-27.

4.3 Degradability

Being degradable is one of the most remarkable properties of polyoxalates.

Curiously, there are not many accessible publications about this important

characteristic. Probably some of the most interesting results about their degradability

were obtained by Park and coworkers, who conducted research in polyoxalates as

potential drug delivery systems as it was mentioned above. They placed the

polyoxalates in form of fine powders in phosphate buffer solution (pH 7.4, 100 mM) at

37 °C. After mixing the solution gently, hydrolyzed polymers were collected at specific

times, and their molecular weights were measured as using GPC. They found that the

molecular weight went from 100% to about 25% in 50 hours as shown in Figure 4-1.27

Figure 4-1. Degradation study of polyoxalate in aqueous solution

4.4 Polyalkylene Oxalates

A methodology was developed to obtain polyoxalates in a greener way, as part of

the goals of this research. Oxalyl chloride has been widely used to synthesize

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polyoxalates showing interesting results26,27 but this would yield HCl as byproduct in this

synthesis, which is not very ecofriendly; therefore “greener” procedures are more

desirable. Using oxalic acid is also a possibility, yielding water as byproduct which is

environmentally favored. However, using esters of oxalic acid such as dimethyl and

diethyl oxalate offer a considerable advantage over oxalic acid which is the lower boiling

point of the eventual byproducts in the polymerization: methanol and ethanol,

respectively. This lower boiling point can be used in order to eliminate this byproduct

easier by heat and/or vacuum; therefore the polymerization will be favored.

Figure 4-2. General reaction of polyoxalates synthesis.

Another issue considered in order to have a greener pathway to obtain polymers

was the absence of solvents; this could be not only friendly to the environment and

avoid potential hazardous chemicals, but also could be interesting in an economic point

of view due fewer expenses in the process.

4.4.1 Synthesis and Characterization

In a first stage of the research, polyoxalates were synthesized increasing one by

one the number of methylene spacers between the oxalate units. To do that different

terminal aliphatic diols starting from 1,3-propanediol until 1,12-dodecanediol were

employed. Polypropylene oxalate and polybutylene oxalate were not soluble in THF

therefore the molecular weight could not be obtained by GPC as the other polymers.

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Figure 4-3. General mechanism for Fisher esterification28

Table 4-1. Polyalkylene oxalates, molecular and thermal properties

Entry Polymer Mw

(kDa) PDI

Yield (%)

Tg (°C)

Tm (°C)

Hm (J g

-1)

HC (J g

-1)

4.1

N.A. N.A. 44.8 -2 78a 53

a --

4.2

19.3 1.73 62.9 7 103a 57

a --

4.3

N.A. N.A. 72.2 -- 98 64 64

4.4

41.4 1.90 79.1 -34 56a 56

a --

4.5

40.7 1.68 77.7 -- 76 65 62

4.6

29.5 1.80 61.9 -48 35a 19

a --

4.7

62.4 1.69 85.1 -- 76 55 64

4.8

71.3 1.76 76.7 -47 40a 52

a 51

4.9

67.6 1.85 83.2 -- 79 57 65

4.10

33.3 2.14 73.4 -29 55 71 71

4.11

69.3 1.76 84.7 -- 80 76 73

a Data obtained from the first heating cycle.

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In general it can be seen the heats of melt for polyalkylene oxalates were very

similar as well as the PDIs.

4.4.2 Effects of Methylene Spacers

Table 4-1 shows the different yields for each polymerization. Starting from some

poor quantities like 45% for polypropylene oxalate to better ones higher than 80% for

polyoctylene, polydecylene, and polydodecylene oxalate, which also showed larger

molecular weights.

Differential scanning calorimetry (DSC) showed for polyoxalates with an odd

number of methylene groups a first cycle with an evident Tm peak for that polymer, but

during the cooling stage the polymer was not able to crystalize, leading to a second

cycle that showed only a Tg for those polymers and an absence of Tm suggesting an

amorphous character of those polymers. On the other hand, first and second heating-

cooling DSC cycles for polyoxalates with even number of methylene spacers were very

similar, showing a typical Tm.

The Tg of the polyalkylene oxalates in general was relatively low. Among the

polyoxalates with an odd number of methylene groups, polypropylene oxalate has the

highest Tg and Tm probably due to the space between the oxalic units which match

better with the oxalic units in the other chains, decreasing the free volume in the

polymers and thus exhibit better packing. A similar case occurs with polybutylene

oxalate, for which the length of the aliphatic region matches with the length of the oxalic

units favoring a good packing between polymer chains as shown in Figure 4.4.

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Figure 4-4. Representation of two chains of polybutylene oxalate

In the particular case of the polynonylene oxalate (nine methylene groups between

oxalic units) the behavior was more like the polymers with even number suggesting that

after a certain length between the oxalic units, the effect of the odd-even spacers is less

relevant.

In Figure 4-5 it can be observed the interesting odd/even tendency of the melting

temperatures along the methylene spacers in the polymer.

Figure 4-5. Melting and glass transition temperatures of polyalkylene oxalates along different number of methylene groups in the backbone

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Although the polyneopentylene oxalate was not included in the graphic because of

its side groups, it is interesting to compare the effect of those with the polypropylene

oxalate. Both have the same length between each oxalic unit along the polymer

backbone, but polyneopentylene oxalate has a higher Tg and Tm. This behavior

suggests that the extra methyl groups of the polyneopentylene oxalate occupy the free

volume that might be between the polypropylene oxalate, reducing the free volume

between polymer chains.

Figure 4-6. Representation of two pairs of chains of polypropylene oxalate and polyneopentylene oxalate

4.4.3 Conclusions

Polyalkylene oxalates were successfully synthesized using a different

methodology in melt and removal of methanol by vacuum under high temperatures,

leading to a greener process. Analyzing the different polymers obtained varying the

number of methylene spacers it was found that polyoxalates with an odd number of

methylene groups between the oxalic units tended to be highly amorphous; meanwhile

29

polyoxalates with an even number of methylene groups were semicrystalline. Yields for

polymerization in general tend to increase with bigger diols as well as the molecular

weights, but PDIs were similar. Heat of melt for polymers was very similar for most of

the polymers.

4.5 Polyarylene and Copoly(Alkylene-Arylene) Oxalates

In order to provide more rigidity to the polymer backbone and obtain higher melting

and glass transition temperatures, aromatic diols were incorporated to the polymer in

different ratios in relation to an alkylene diol. The 1,10-decanediol was chosen not only

because it provided interesting properties to the polyoxalates such as good solubility,

good yield, relatively high crystallinity melting point, but also because it is potentially

biorenewable.17 Resorcinol bis(beta-hydroxyethyl)ether is a diol derivative from

resorcinol, an aromatic diol which was extended not only to provide some flexibility to

the polymer chain but also to make capable of polymerization with dimethyl oxalate.

Figure 4-7. Resorcinol bis(beta-hydroxyethyl)ether (4.12).

Indeed, polymerization with resorcinol itself was attempted without success under

our conditions as it could be expected considering the low reactivity of phenols in a

typical acid catalyzed Fisher esterification.28 Thus the functionalization of the phenolic

groups to primary alcohols would make the incorporation of this compound feasible.

30

4.5.1 Synthesis and Characterization

Feed of aliphatic and aromatic diols changed in amounts of 10 mol%. The actual

incorporation was confirmed by 1H NMR. Both diols were effectively incorporated in the

backbone of the polymer in ratios close to the feed.

Table 4-2. Copoly(alkylene-arylene) oxalates, macromolecular and thermal properties

Entry Feed percentage

Inc. of “n” by

1H NMR (%)

Mw (kDa)

PDI Yield (%)

Tg (°C)

Tm (°C)

Hm (J/g) Aliphatic

section “m” (%)

Aromatic section “n”

(%)

4.9 100 0 0 67.6 1.85 83.2 -- 79 57 4.13 90 10 11 64.9 1.80 76.2 -24 70 52 4.14 80 20 22 71.3 1.79 80.0 -20 66 46 4.15 70 30 26 59.8 1.84 83.4 -15 64 51 4.16 60 40 38 62.3 1.95 70.5 -18 58 7 4.17 50 50 48 63.7 2.12 75.8 -5 95 25 4.18 40 60 57 57.5 2.07 61.1 4 103 41 4.19 30 70 68 43.7 1.95 72.6 14 122 20 4.20a 20 80 77 N.A. N.A. 73.2 25 133 35 4.21a 10 90 84 N.A. N.A. 46.4 29 138 41 4.22a 0 100 100 N.A. N.A. 56.4 34 156 50 a Polymers not soluble in THF

To determine incorporation of the diols, polymers 4.9 and 4.22 were compared

and peaks were identified, respectively. It was found that the quintuplet at 1.73 ppm

which corresponds to four of the protons in the aliphatic region did not overlap with any

other peak from the aromatic diol. Furthermore, the multiplet at 6.51 ppm corresponding

to three of the aromatic protons did not overlap with any signal of the aliphatic diol.

Considering this and comparing areas of these peaks led us to confirm that both

aliphatic and aromatic diols were fully incorporated into the polymer. Figure 4-8 shows a

typical comparison of the different spectra in order to calculate the incorporation.

31

Figure 4-8. 1H NMR spectra of polymers 4.9, 4.16, and 4.22 for incorporation calculation

4.5.2 Effect of the Incorporation of Aromatic Units into the Polymer

The increase of the aromatic diol feed in the polymer at the beginning showed a

decrease in the Tm of the copolymer from 79 °C (Tm of the polydecylene oxalate) to a

minimum of 58 °C at a ratio of 40:60, after this point the tendency was reversed and the

Tm was increased to 156 °C as shown in the Figure 4-9.

Figure 4-9. Melting temperature of copoly(alkylene-arylene) oxalates.

32

On the other hand, Tg showed a linear increasing behavior along the incorporation

of the aromatic diol in the copolymer. This behavior was expected according to the Fox

equation which predicts the Tg of a copolymer or a polymer blend based on the

individual Tg of each homopolymer.29 Figure 4-11 shows this behavior.

Figure 4-10. Fox equation for random copolymers, where w is weight fraction

Figure 4-11. Glass transition temperature of copolymers

4.5.3 Degradation

The samples obtained were stored in vials, inside a cabinet, away from light under

a regular atmosphere and about a year later, the molecular weights were obtained via

GPC in the same conditions they were obtained before as shown in Table 4-3. It seems

that the presence of moisture in the headspace of the vial was enough to hydrolyze the

polymer chains allowing this decrease in molecular weight.

33

Table 4-3. Degradation of copoly(alkylene-arylene) oxalates

Entry

Sept 2011 Oct 2012

Feed percentage m

(%)

Feed percentage n

(%)

Mw (kDa)

PDI Mw

(kDa) PDI

4.9 100 0 67.6 1.85 12.2 1.76

4.13 90 10 64.9 1.80 6.4 1.79

4.14 80 20 71.3 1.79 4.9 1.66

4.15 70 30 59.8 1.84 4.3 1.62

4.16 60 40 62.3 1.95 2.6 1.73

4.17 50 50 63.7 2.12 2.5 1.69

4.18 40 60 57.5 2.07 2.9 1.67

4.19 30 70 43.7 1.95 2.6 1.58

4.5.4 New Ideas

4.5.4.1 Copolymers with 1,4-butanediol

1,4-butanediol is a potentially biorenewable diol,11,12 and copolymerizations with

this compound could yield a new series of copoly(alkylene-arylene) oxalates with

presumably higher polymer melting temperatures.

Figure 4-12. Copolymer using 1,4-butanediol as comonomer.

4.5.4.2 Polyoxalates based on hydroquinone

Another potential biorenewable diol is hydroquinone,17 an isomer of resorcinol.

Using similar methodology it can be reacted as resorcinol to obtain an extended diol

more reactive with oxalates. Because of the linearity of this diol, more crystalline

polymers would be expected from this monomer, as well as copolymers with aliphatic

diols.

34

Figure 4-13. Poly resorcinol bis(beta-hydroxyethyl)ether oxalate

4.5.4.3 Vanillin based diols for polyarylene oxalates

Vanillin is an aromatic compound present in lignin -together with cellulose a

component of plants- and very abundant in nature; it is the second main constituent of

wood and one of the top polymers in abundance on earth along with cellulose.30,31

Because of the presence of a phenolic group, an extension of this alcohol would be

desirable in order to have a successful polymerization, as well as the reduction of the

aldehyde group to obtain the diol. Unfortunately this would lead to an unsymmetrical

diol; therefore the polymer could be very amorphous due to random regiochemistry, but

the presence of aromatic sp2 carbons in the backbone could provide high Tg.

Figure 4-14. Vanillin based unsymmetrical diol

Another approach can be used in order to obtain vanillin based symmetrical diols,

which is the coupling of two molecules of vanillin using an “aliphatic bridge” and finally

reducing the aldehyde groups. Varying the number of methylene groups between the

coupled aromatic rings the properties of the eventual polyoxalates could be tuned.

35

Figure 4-15. Vanillin based symmetrical diols

4.5.5 Conclusions

Copolymerizations of aliphatic and aromatic diols with dimethyl oxalate were

successfully achieved. Incorporation of the aromatic diol was proved using 1H NMR with

incorporation results very close to the feed ratios. It was proven that the addition of

aromatic fuctionality provided higher Tg with their incorporation in the polymer backbone

exhibiting a linear increase according to the Fox equation; meanwhile Tm decreased to a

minimum at 40:60 incorporation, to finally reach a maximum when the polymer had a

100% of the aromatic-based monomer.

36

CHAPTER 5 EXPERIMENTAL PROCEDURES

5.1 Molecular Characterization

Proton and carbon nuclear magnetic resonance (1H and 13C NMR) spectra were

recorded using a Varian Inova 500 MHz spectrometer and/or Mercury 300 MHz.

Chemical shifts are reported in parts per million (ppm) downfield relative to

tetramethylsilane (TMS, 0.0 ppm) or residual proton in the specified solvent. Coupling

constants (J) are reported in Hertz (Hz). Multiplicities are reported using the following

abbreviations: s, singlet; d, doublet; t, triplet; q, quartet; quin, quintuplet; m, multiplet; br,

broad.

Differential scanning calorimetry thermograms were obtained with a DSC Q1000

from TA instruments. About 3 mg of each sample were massed and added to a sealed

pan that passed through a heat/cool/heat cycle at 10 °C/min. The temperature ranged

from –100 to 200 ºC.

Thermogravimetric analyses were measured under nitrogen with a TGA Q5000

from TA Instruments. About 5-10 mg of each sample were heated at 10 °C/min from

room temperature to 600 °C.

Gel permeation chromatography (GPC) was performed at 40 °C using a Waters

Associates GPCV2000 liquid chromatography system with an internal differential

refractive index detector and two Waters Styragel HR-5E columns (10 μm PD, 7.8 mm

i.d., 300 mm length) using HPLC grade tetrahydrofuran (THF) as the mobile phase at a

flow rate of 1.0 mL/min. Calibration was performed with narrow polydispersity

polystyrene standards.

37

5.2 Polymerization Procedures

The polymerizations were typically conducted in a round bottom flask, connected

to a rotary evaporation bump trap that was connected to a vacuum line. With this

apparatus, molecules of condensation could be collected and visualized in the bump

trap, followed by removal of all volatiles without changing the initial glassware

configuration. In the first step, dimethyl oxalate was added to the flask with one mole

equivalent of the corresponding diol(s) and about 2 mol% of para-toluenesulfonic acid

(p-TSA) and stirred under nitrogen atmosphere for one hour. Later the temperature was

raised to 130 °C and stirred for two more hours. The next step consisted of pulling

vacuum for an hour, and finally increasing the temperature of the system to 220 °C for

three hours.

Figure 5-1. Polymerization device: A hot plate with temperature control, oil bath, flask containing the reagents and connection to a vacuum line through a bump trap.

38

For the polymer workup, the product was allowed to cool at room temperature and

dissolved in about 30-40 mL of methylene chloride for entries 4.1 to 4.11 and 4.13 to

4.19 or dimethyl sulfoxide (DMSO) for entries 4.20 to 4.22. The polymer was

precipitated by the addition of the solution in about 100 mL of cold methanol. The

system was filtered and the polymer was dried under vacuum.

Figure 5-2. Polyprolylene oxalate (4.1)

1H NMR (299MHz, CHLOROFORM-d) = 4.42 (t, J = 6.1 Hz, 4 H), 2.20 (quin, J =

6.1 Hz, 2 H)

13C NMR (126MHz, CHLOROFORM-d) = 157.4, 63.5, 27.3.

Figure 5-3. Polyneopentylene oxalate (4.2)

1H NMR (500MHz, CHLOROFORM-d) = 4.12 (s, 4 H), 1.07 (s, 6 H).

13C NMR (126MHz, CHLOROFORM-d) = 157.1, 70.9, 35.0, 21.5.

Figure 5-4. Polybutylene oxalate (4.3)

1H NMR (500MHz, CHLOROFORM-d) = 4.38 - 4.31 (m, 4 H), 1.92 - 1.84 (m, 4

H).

13C NMR (126MHz, CHLOROFORM-d) = 157.6, 66.3, 24.8.

39

Figure 5-5. Polypentylene oxalate (4.4)


7.2 Hz, 4 H), 1.51 (quin, J = 7.5 Hz, 2 H).

13C NMR (126MHz, CHLOROFORM-d) = 157.8, 66.7, 27.8, 22.1.

Figure 5-6. Polyhexylene oxalate (4.5)


7.0 Hz, 4 H), 1.49 - 1.40 (m, 4 H).

13C NMR (126MHz, CHLOROFORM-d) = 157.9, 110.0, 66.8, 28.1, 25.3.

Figure 5-7. Polyheptylene oxalate (4.6)

1H NMR (300MHz, CHLOROFORM-d) = 4.28 (t, J = 6.9 Hz, 4 H), 1.83 - 1.66 (m,

4 H), 1.49 - 1.32 (m, 6 H).


Figure 5-8. Polyoctylene oxalate (4.7)

40


7.1 Hz, 4 H), 1.44 - 1.30 (m, 8 H).


Figure 5-9. Polynonylene oxalate (4.8)


6.8 Hz, 4 H), 1.44 - 1.27 (m, 10 H).

13C NMR (126MHz, CHLOROFORM-d) = 158.0, 67.1, 29.2, 29.0, 28.2, 25.6.

Figure 5-10. Polydecylene oxalate (4.9)


6.9 Hz, 4 H), 1.47 - 1.19 (m, 12 H).


Figure 5-11. Polyundecylene oxalate (4.10)


7.0 Hz, 4 H), 1.43 - 1.23 (m, 14 H).


41

Figure 5-12. Polydodecylene oxalate (4.11)


7.0 Hz, 4 H), 1.44 - 1.25 (m, 16 H).

13C NMR (126MHz, CHLOROFORM-d) = 158.0, 67.2, 29.5, 29.4, 29.1, 28.3,

25.7.

Figure 5-13. Copolymer (4.17)

1H NMR (300MHz, CHLOROFORM-d) = 7.22 - 7.10 (m, 1 H), 6.60 - 6.43 (m, 3

H), 4.61 (br. s., 4 H), 4.33 - 4.17 (m, 8 H), 1.81 - 1.65 (m, 4 H), 1.29 (br. s., 12 H).

13C NMR (126MHz, CHLOROFORM-d) = 159.4, 158.0, 157.8, 157.5, 157.3,

130.1, 107.5, 101.9, 67.3, 67.1, 65.2, 64.9, 29.3, 29.1, 28.2, 25.6.

Figure 5-14. Poly resorcinol bis(beta-hydroxyethyl)ether oxalate (4.22)

1H NMR (299MHz, DMSO-d6) = 7.31 - 7.03 (m, 1 H), 6.68 - 6.40 (m, 3 H), 4.53

(d, J = 2.8 Hz, 4 H), 4.33 - 4.12 (m, 4 H).

13C NMR (126MHz, DMSO-d6) = 159.7, 157.5, 130.6, 130.5, 110.0, 107.8, 107.2,

101.7, 70.0, 65.8, 65.5, 60.0.

42

5.3 Synthesis of Aromatic Diol

Figure 5-15. Synthesis of Resorcinol bis(beta-hydroxyethyl)ether (4.12)

Resorcinol and ethylene carbonate were added with a catalytic amount of

triphenylphosphine (PPh3), melted at 150 °C and stirred under nitrogen atmosphere

overnight. Then 200 mL of methanol were added to the reaction in ice bath, filtered and

washed with cold methanol to finally dry under vacuum. The compound was confirmed

by NMR.

1H NMR (500MHz, DMSO-d6) = 7.16 (t, J = 8.3 Hz, 1 H), 6.52 - 6.47 (m, 3 H),

4.84 (t, J = 5.4 Hz, 2 H), 3.95 (t, J = 5.2 Hz, 4 H), 3.70 (q, J = 5.2 Hz, 4 H).

13C NMR (126MHz, DMSO-d6) = 159.9, 129.9, 106.7, 101.2, 69.5, 59.6.

43

APPENDIX A PROTON AND CARBON NMR

Figure A-1. 1H NMR of polymer 4.1

Figure A-2. 13C NMR of polymer 4.1

44



45



46



47



48



49



50



51



52



53



54

Figure A-23. 1H NMR of compound 4.12

Figure A-24 13C NMR of compound 4.12

55



56



57



58



59



60



61



62



63



64



65

APPENDIX B POLYMER DATA

Figure B-1. TGA of polypropylene oxalate 4.1

Figure B-2. DSC of polypropylene oxalate 4.1

66

Figure B-3. TGA of polyneopentylene oxalate 4.2

Figure B-4. DSC of polyneopentylene oxalate 4.2

67

Figure B-5. TGA of polybutylene oxalate 4.3

Figure B-6. DSC of polybutylene oxalate 4.3

68

Figure B-7. TGA of polypentylene oxalate 4.4

Figure B-8. DSC of polypentylene oxalate 4.4

69

Figure B-9. TGA of polyhexylene oxalate 4.5

Figure B-10. DSC of polyhexylene oxalate 4.5

70

Figure B-11. TGA of poly heptylene oxalate 4.6

Figure B-12. DSC of polyheptylene oxalate 4.6

71

Figure B-13. TGA of polyoctylene oxalate 4.7

Figure B-14. DSC of polyoctylene oxalate 4.7

72

Figure B-15. TGA of polynonylene oxalate 4.8

Figure B-16. DSC of polynonylene oxalate 4.8

73

Figure B-17. TGA of polydecylene oxalate 4.9

Figure B-18. DSC of polydecylene oxalate 4.9

74

Figure B-19. TGA of polyundecylene oxalate 4.10

Figure B-20. DSC of polyundecylene oxalate 4.10

75

Figure B-21. TGA of polydodecylene oxalate 4.11

Figure B-22. DSC of polydodecylene oxalate 4.11

76

Figure B-23. TGA of copolymer 4.13

Figure B-24. DSC of copolymer 4.13

77



78



79



80



81



82



83



84



85



86

Figure B-43. GPC of polyneopentylene oxalate 4.2

Figure B-44. GPC of polypentylene oxalate 4.4

87

Figure B-45. GPC of polyhexylene oxalate 4.5

Figure B-46. GPC of polyheptylene oxalate 4.6

88

Figure B-47. GPC of polyoctylene oxalate 4.7

Figure B-48. GPC of polynonylene oxalate 4.8

89

Figure B-49. GPC of polydecylene oxalate 4.9

Figure B-50. GPC of polyundecylene oxalate 4.10

90

Figure B-51. GPC of polydodecylene oxalate 4.11

Figure B-52. GPC of copolymer 4.13

91



92



93



94

LIST OF REFERENCES

(1) Windholz, M.; Budavari, S.; Blumetti, R. F.; Otterbein, E. S.; Eds. In The Merk Index, an encyclopedia of chemicals, drugs and biological, Tenth edition; Merck & Co., Inc.: Rahway, N.J., 1983, p 991

(2) United States Department of Agriculture. National Agricultural Library. http://www.nal.usda.gov/fnic/foodcomp/Data/Other/oxalic.html (accessed November 4, 2012)

(3) Wallace, W. Manufacture of Oxalates and Oxalic Acid. U.S. Patent 1,602,802, Oct 12, 1926.

(4) Eiichi, Y.; Tomiya, I.; Tsuyoshi, S.; Yukio, Y. Process for the production of oxalic acid. U.S. Patent 3,678,107, July 18, 1972.

(5) Rivetti, F.; Romano, U. J. Organomet. Chem. 1979, 174, 221-226.

(6) Amadio, E. Oxidative Carbonylation of Alkanols Catalyzed by Pd(II)-Phosphine Complexes. Ph.D. Dissertation, Ca’ Foscari University, Venice, 2009.

(7) Morris, J. E.; Oakley, D.; Pippard, D. A.; Smith, D. J. H. J. Chem. Soc. Chem. Commun. 1987. 410- 411.

(8) Gaffney, A. M.; Sofranko, J. A. Preparation of Dialkyl Oxalates By The Oxidative Carbonylation of Alcohols with a Heterogeneous Pd-V-P-Ti Containing Catalyst System. U.S. Patent 4,447,638, May 8, 1984.

(9) http://www.chem.uu.nl/brew/BREWsymposiumWiesbaden11mei2005/WEBSITEBrewPresentations51105.PDF (accessed November 4, 2012)

(10) Biebl, H.; K. Menzel, K.; Zeng, A.; Deckwer, W. Appl. Microbiol. Biotechnol.1999, 52 (3), 289–297.

(11) Genomatica. Sustainable Chemicals. http://www.genomatica.com/products/bdo/ (accessed November 4 2012)

(12) Burk, M. J. Int. Sugar J. 2010, 112, 30-35.

(13) Mutly, H.; Meier, M. Eur. J. Lipid Sci. Technol. 2010, 112, 10-30.

(14) Noweck, K.; Grafahrend, W. “Fatty Alcohols” in Ullmann’s Encylopedia of Industral Chemistry 2006.

(15) Stevens, M. P.; Chemical Structure and Polymer Morphology. Polymer Chemistry, Third Edition; Oxford University Press: New York, 1999; p 71.

(16) IARC Monographs. http://monographs.iarc.fr/ENG/Monographs/vol71/mono71-52.pdf (accessed Nov 4 2012)

http://www.nal.usda.gov/fnic/foodcomp/Data/Other/oxalic.htmlhttp://worldwide.espacenet.com/textdoc?DB=EPODOC&IDX=US3678107http://www.chem.uu.nl/brew/BREWsymposiumWiesbaden11mei2005/WEBSITEBrewPresentations51105.PDFhttp://www.chem.uu.nl/brew/BREWsymposiumWiesbaden11mei2005/WEBSITEBrewPresentations51105.PDFhttp://www.genomatica.com/products/bdo/http://monographs.iarc.fr/ENG/Monographs/vol71/mono71-52.pdfhttp://monographs.iarc.fr/ENG/Monographs/vol71/mono71-52.pdf

95

(17) Ran, N.; Knop, D. R.; Draths, K. M.; Frost, J. W. J. Am. Chem. Soc. 2001, 123, 10927-10934.

(18) Carothers, W.; Arvin, J.; Dorough, G. J. Am. Chem. Soc, 1930, 52, 3292-3300.

(19) Finelli, L., Lotti, N.; Murani, A. Eur. Polym. J. 2002, 38, 1987-1993.

(20) Tanaka, H.; Adachi, F.; Kunimura, M.; Kurachi, K. Polym. Eng. Sci. 2005, 45, 163-173.

(21) Shin, J.; Yeh, K. J. Appl. Polym. Sci. 1999, 74, 921-936.

(22) Coquard, J.; Sedivy, P.; Ruaud, M.; Verrier, J. Bioresorbable Surgical Articles. U.S. Patent 4,032,933, July 5, 1977.

(23) Shalaby, S.; Jamiolkowski, D. Poly(Alkylene Oxalate) Absorbable Coating for Sutures. U.S. Patent 4,105,034, August 8, 1978.

(24) Shalaby, S.; Jamiolkowski, D. Synthetic Absorbable Surgical Devices of Poly(Alkylene Oxalates). U.S. Patent 4,205,399, June 3, 1980.

(25) Holland, S.; Tighe, B.; Gould, P. J. Controlled Release, 1986, 4, 155-180.

(26) Kim, S.; Seong, K.; Kim, O.; Kim, S.; Seo, H.; Lee, M.; Khang, G.; Lee, D. Biomacromolecules, 2010, 11, 555-560.

(27) Park, H.; Kim, S.; Kim, S.; Song, Y.; Seung, K.; Hong, D.; Khang, G.; Lee, D. Biomacromolecules, 2010, 11, 2103-2108.

(28) Brown, W.; Foote, C.; Iverson, B.; Anslyn, E. Organic Chemistry, Fifth Edition; Brooks/Cole Cengage Learning: Belmont, CA, 2009; p 635.

(29) Painter, P.; Coleman, M. Essentials of Polymer Science and Engineering; DEStech Publications, Inc.: Lancaster, PA., 2009; p. 328.

(30) Boerjan, W.; Ralph, J.; Baucher, M. Annu. Rev. Plant Biol. 2003, 54, 519.

(31) Davin, B.; Lewis, N. Current Opinion in Biotechnology 2005, 16, 407.

96

BIOGRAPHICAL SKETCH

John Jairo Garcia Ocampo was born in 1982 in Cali, Colombia. After he attended

high school he made his studies in chemistry at Universidad del Valle in Cali where he

obtained his bachelor degree in chemistry in December 2006. During his lasts years of

bachelor he developed his thesis at the sugarcane research center (CENICANA) in

Florida, Valle del Cauca, Colombia, developing research with cellulosic material, and

after the culmination of this work he started working at the laboratory of quality control in

Bayer, Cali. After his graduation he moved to Lloreda S.A. in Yumbo, Valle del Cauca,

when he worked also in the laboratory of quality control for a couple of years before

moving finally to Gainesville in the U.S. to join the Organic Division of the Chemistry

Department at the University of Florida in August 2009, focusing his research in the

synthesis of potential biorenewable and biodegradable polymers under the direction of

Dr. Stephen A. Miller obtaining his Master of Science degree in December 2012.

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