The effects of molecular structure on sol-to-gel transition of biodegradable poly(depsipeptide-co-lactide)-g-PEG copolymers |
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Authors: | Akihiro Takahashi Masaya Umezaki Yasuyuki Yoshida Akinori Kuzuya |
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Affiliation: | 1. Organization for Research and Development of Innovative Science and Technology (ORDIST), Kansai University, 3-3-35 Yamate, Suita, Osaka 564-8680, Japan;2. Faculty of Chemistry, Materials and Bioengineering, Department of Chemistry and Materials Engineering, Kansai University, 3-3-35 Yamate, Suita, Osaka 564-8680, Japan;3. Organization for Research and Development of Innovative Science and Technology (ORDIST), Kansai University, 3-3-35 Yamate, Suita, Osaka 564-8680, Japan |
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Abstract: | We report on the effects of number and length of PEG chains in poly(depsipeptide-co-dl-lactide)-g-poly(ethylene glycol) (P(DG-dl-LA)-g-PEG) copolymers on their sol-to-gel transition behavior. The graft-type copolymer is suitable for the systematic study of the effects of molecular structure and hydrophilic/hydrophobic balance on its sol-to-gel transition. We prepared various P(DG-dl-LA)-g-PEG copolymers through coupling reactions between the pendant carboxylic acid groups of P(GD-dl-LA) and the end hydroxyl group of MeO-PEG having various molecular weights. Temperature-responsive sol-to-gel transition of the obtained copolymer solution in phosphate-buffered solution (pH 7.4, ionic strength = 0.14) was investigated by the test tube inverting method and rheological measurements. P(GD-dl-LA)-g-PEG copolymer prepared from higher molecular weight PEG showed higher sol-to-gel transition temperatures compared with the copolymers prepared from lower molecular weight PEG, although these copolymers have similar weight content of PEG (23–24?wt.%). Similar trends were observed for groups of copolymers whose PEG contents were 27 or 30?wt.%. These results are informative for providing strategies on rational design of thermo-gelling polymers. |
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Keywords: | biodegradable depsipeptide sol-to-gel transition temperature responsiveness |
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