Novel synthesis of biodegradable poly(lactide-co-ethylene glycol) block copolymers |
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Authors: | Yahia Lemmouchi Michael C Perry Allan J Amass Khirud Chakraborty Francois Schué |
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Institution: | 1. Chemical Engineering and Applied Chemistry, Aston University, Aston Triangle, Birmingham, B4 7ET, United Kingdom;2. Robinson Brothers Limited, Phoenix Street, West Bromwich, B70 0AH, United Kingdom;3. Laboratoire de Chimie Macromoleculaire, University of Montpellier II, Place Bataillon, 34095, Montpellier, France |
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Abstract: | Biodegradable and amphiphilic diblock copolymers polylactide-block-poly(ethylene glycol)] and triblock copolymers polylactide-block-poly(ethylene glycol)-block-polylactide] were synthesized by the anionic ring-opening polymerization of lactides in the presence of poly(ethylene glycol) methyl ether or poly(ethylene glycol) and potassium hexamethyldisilazide as a catalyst. The polymerization in toluene at room temperature was very fast, yielding copolymers of controlled molecular weights and tailored molecular architectures. The chemical structure of the copolymers was investigated with 1H and 13C NMR. The formation of block copolymers was confirmed by 13C NMR and differential scanning calorimetry investigations. The monomodal profile of the molecular weight distribution by gel permeation chromatography provided further evidence of block copolymer formation as well as the absence of cyclic species. Additional confirmation of the block copolymers was obtained by the substitution of 2-butanol for poly(ethylene glycol); butyl groups were clearly identified by 1H NMR as polymer chain end groups. The effects of the copolymer composition and lactide stereochemistry on the copolymer properties were examined. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2235–2245, 2007 |
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Keywords: | biodegradable block copolymers catalysts polyesters ring-opening polymerization |
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