Effect of Microstructures on the Phase Transition Behavior of P(CL-GL)-PEG-P(CL-GL) Triblock Copolymer Aqueous Solutions

✍ Scribed by Zhiqiang Jiang; Yujing You; Qun Gu; Jianyuan Hao; Xianmo Deng

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 161 KB
• Volume: 29
• Category: Article
• ISSN: 1022-1336
• DOI: 10.1002/marc.200800186

✦ Synopsis

Abstract

Amphiphilic poly[(ε‐caprolactone)‐co‐glycolide]‐block‐poly(ethylene glycol)‐block‐poly[(ε‐caprolactone)‐co‐glycolide) [P(CL‐GL)‐PEG‐P(CL‐GL)] triblock copolymers with different average lengths of caproyl sequences (L~CL~) were synthesized by ring‐opening polymerization at different temperatures. A 25% aqueous solution of the copolymer with L~CL~ = 11.0 formed a gel, owing to strong crystallinity‐induced hydrophobicity at low temperature, and underwent a gel‐sol transition (UCST behavior) when the temperature was increased to 40 °C. In contrast, the solution of copolymer with L~CL~ = 6.7 underwent a sol‐gel transition (LCST behavior) due to micelle aggregation. However, a clear sol‐turbid sol phase transition was observed for the copolymer with more random microstructures (L~CL~ = 5.2).

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