Thermoreversible gelation of poly(ethylene oxide) biodegradable polyester block copolymers. II

Sung Won Choi, Si Young Choi, Byeongmoon Jeong, Sung Wan Kim, Doo Sung Lee

Research output: Contribution to journalArticlepeer-review

83 Scopus citations

Abstract

Poly(ethylene oxide)-b-poly(L-lactic acid) (PEO-PLLA) diblock copolymers were synthesized via a ring opening polymerization from poly(ethylene oxide) and L-lactide. Stannous octoate was used as a catalyst in a solution polymerization with toluene as the solvent. Their physicochemical properties were investigated by using infrared spectroscopy, 1H-NMR spectroscopy, gel permeation chromatography, and differential scanning calorimetry, as well as the observational data of gel-sol transitions in aqueous solutions. Aqueous solutions of PEO-PLLA diblock copolymers changed from a gel phase to a sol phase with increasing temperature when their polymer concentrations are above a critical gel concentration. As the PLLA block length increased, the gel-sol transition temperature increased. For comparison, diblock copolymers of poly(ethylene oxide)-b-poly(L-lactic acid-co-glycolic acid) [PEO-P(LLA/GA)] and poly(ethylene oxide)-b-poly(DL-lactic acid-co-glycolic acid) [PEO-P(DLLA/GA)] were synthesized by the same methods, and their gel-sol transition behaviors were also investigated. The gel-sol transition properties of these diblock copolymers are influenced by the hydrophilic/hydrophobic balance of the copolymer, block length, hydrophobicity, and stereo-regularity of the hydrophobic block of the copolymer.

Original languageEnglish
Pages (from-to)2207-2218
Number of pages12
JournalJournal of Polymer Science, Part A: Polymer Chemistry
Volume37
Issue number13
DOIs
StatePublished - 1 Jul 1999

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