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Aqueous Nanodispersions of Biodegradable Polyesters forNanofiber Preparation by Electrospinning
Andreas Greiner
Philipps-Universität Marburg, Department of ChemistryHans-Meerwein str, 35032 Marburg, Germany
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From water processable to water stable
Processing from water
Nanomaterial
Water stable???
Biodegradable Polyesters
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The visionProtection by mating disruption with pheromonesfrom artificial dispensers
Requirements- Dispensers have to create homogenous phermone cloud- Dispensers have to be biodegradable- Dispensers have to be stable during release of pheromone – suspension electrospinning- Dispensers have to release pheromone steadily
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The conceptUse of electrospun pheromone releasing nonwovens
Nanofiber nonwovensPheromone releasingmicrocapsules
The green approach
•Water based formulation
•Water stable nonwoven
•Degradable nonwoven
•Phermone release
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In brief about nonwovens by eletrospinningA coating technique
Fiber diameters 1 – 10.000 nm
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From lab scale to technical scale
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Polycaprolactone
Polymers for electrospinning
Polylactide
Nylon 66 PMMA
Nylon 6
PolystyrenePolyethylene
Polypropylene
Silk
PET
TPU Polyethyleneoxide
PolyvinylalcoholPolyvinylpyrollidonPolyacrylic acid
Chitosan
DNA
PolycarbonatePolyethersulfone
Polyimide
Fibrinogen
Collagen
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Take home messageSo many options by electrospinningfor novel nanofiber nonwovens
Reviews: Greiner, Wendorff, Angew. Chem. Int. Ed. 2007, 46, 5670Agarwal, Wendorff, Greiner, Polymer 2008, 49, 5603 (Biomed.)Agarwal, Greiner, Wendorff, Adv. Funct. Mater. 2009, 19, 1 Agarwal, Greiner, Wendorff, Adv. Mater. 2009, 21, 1 (Tissue Eng.)Agarwal, Wendorff, Greiner, Macromol. Chem. Rapid Commun. 2010, 31, Agarwal, Greiner, Special Topic Issue on Eletrospinning, Polym. Adv. Techn., 2011
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Nanofiber nonwovens ???Pheromone releasingMicrocapsules???
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How to electrospin for water stable biodegradablepolymers from water?
Well established biodegradable polymers:Aliphatic polyesters (polylactide, PCL…)
Problem: soluble only in hazardous solventsNo electrospinning on fields possible
The possible solution:Suspension electrospinning of secondary suspensions of biodegradable polyesters
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How to get secondary suspensions of biodegradablepolymers?
Water soluble blockBiodegradable
hydrophobic block
Suspensions bymicell formation
H2O
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Synthesis diblock copolyester
Mn = 6400 (GPC – PS standards Mw / Mn = 2.1Insoluble in waterTm = 58 °C
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Secondary dispersion of the diblockcopolyester in water
Follow protocol of solvent displacement method• Dissolve polyester and Brij78 (10%) in actone• Add water• Apply ultrasound
Stable suspensionSolid content: 2.5 %
Too low for electrospinning
112 nm
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Up-concentration of the secondary dispersionDialysis of suspension
Dialysistube
Suspensionof polyester
Water+ PVA(16%)
Set-up of dialysis
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Up-concentration of the secondary dispersionDialysis of suspension
Stable suspensionSolid content: 16 %
Good for electrospinning
109 nm
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Take home message
Aliphatic water insolublepolyesters can be dis-persed in water up to 20 %
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Concept for submicron fibers by suspensionelectrospinning
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Solution of template polymer
Electrospinning
Removal of template polymer
Template polymer Latex particle
Water
Stoiljkovic et al., Polymer 2007, 48, 3974Stoiljkovic et al., Macromolecules 2009, 42, 6147J. Sun et al., Macromol. Chem. Rapid Commun. 2010, 31, 2077P. Bansal et al., in prep.
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Electrospinning of up-concentrated
secondary dispersions
+ 3 % PEOElectrospinning
Fiber diameter300 – 500 nm
J. Sun, K. Bubel, F. Chen, T. Kissel, S. Agarwal, A. Greiner,Macromol. Chem. Rapid Commun., 2010
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As-spun After water treatment for 2 days
Slight reduction of fiber diameterNo Brij78 and PEO left
Polyester+PEO+Brij78No suspension particles visible
Water treatment of electrospun fibers of secondarydispersions
Water-stable electrospun biodegradable fibersfrom aqueous secondary dispersions
Water-stable electrospun biodegradable fibersfrom aqueous secondary dispersions
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How about the biodegradability
0 20 40 60 80 1000
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40
60
80
100
Wei
ghtl
oss(
%)
Time of degradation(h)
with enzyme (Pseudomonas lipase)
without enzyme
Fast enzymatic degradation
Slow hydrolytic degradation
Low cytoxicity (without tenside)
F. ChenY. Zhang
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Take home message
Electrospinning of secondarydispersions of alipahatic poly-esters results in water stablebiodegradable nanofibernonwovens
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Nanofiber nonwovensPheromone releasingMicrocapsules???
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Water dispersed phermone filled microcapsules
Requirements for microcapsules
- Uptake of large amount of hydrophobic pheromone
- Microcapsules should be biodegradable
- Microcapsules should allow release of pheromone
- Microcapsules of should be well dispersable in water
The pheromone
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Water dispersed phermone filled microcapsules
The hypothesisOligolactides with hydroxy/carboxylateend groups will fullfill all requirementsfor water dispersion and biodegradability
The answer: It is wrong
HOO
O
O
O-K+
n
OLA
New hypothesisPheromone will act as hydrohob and thereby stabilize dispersions
The answer: It is right
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The observationStable dispersions OLA with pheromoneNo stable dispersions of OLA alone
OLA/pheromone/BrijS2010 / 10 / 1 % P. Bansal
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Take home message
Dispersions of OLA are onlyStable up to 10 % withpheromone as stabilizer!!!
Without pheromone
With pheromone
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How to measure dispenser efficiency on field?
Nonwoven with pheromone
Cage with lonely female beatle–how many male will visit here?Ass less as better for us – Quantification!
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Pheromone release is not yet retarted enough
Our serendiptywill continue
Take home messageBiodegradable polyester nanoparticle dispersions up tp 20 %Biodegradable water stable polyester nanofibers from waterHigh solid content OLA microcapsules dispersion with pheromones
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Support: University of Marburg, DFG, BMBF, BLE, BASF
The teams: Agarwal and Greiner group
We do not risk because it is difficult - It is difficult because we do not riskSeneca
Partners - Profs: S. Agarwal, J. H. Wendorff, G. Leithold
Poster D-PO4-27: Thermo- and photoresponsive Nanomats by Electrospinning…..(Agarwal / Brandl) – today afternoon only!!!
