title: Thermoreversible gel-sol behavior of biodegradable PCL-PEG-PCL triblock copolymer in aqueous solutions.
abstract: A series of biodegradable PCL-PEG-PCL block copolymers were successfully synthesized by ring-opening polymerization of epsilon-caprolactone initiated by poly(ethylene glycol) (PEG), which were characterized by (1)H NMR, (13)C NMR, and FTIR. Their aqueous solution displayed special gel-sol transition behavior with temperature increasing from 4 to 100 degrees C, when the polymer concentration was above corresponding critical gel concentration (CGC). The gel-sol phase diagram was recorded using test tube inverting method and DSC method, which depended not only on chemical composition of copolymers, but also on heating history of copolymer's aqueous solution. As a result, the gel-sol transition temperature could be adjusted, which might be very useful for its application in biomedical fields such as injectable drug delivery system. And the typical shell-core structure of PCL-PEG-PCL micelles was introduced. The micelle-packing and partial crystallization might be the key gelation machanism for this gel-sol transition behavior of PCL-PEG-PCL aqueous solution.
authors: State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu 610041, China.
authors: Cai Bing
authors: CB
authors: Liu
authors: Chang Yang
authors: CY
authors: Gong
authors: Mei Juan
authors: MJ
authors: Huang
authors: Ji Wei
authors: JW
authors: Wang
authors: Yi Feng
authors: YF
authors: Pan
authors: Yang De
authors: YD
authors: Zhang
authors: Guo Zheng
authors: GZ
authors: Li
authors: Ma Ling
authors: ML
authors: Gou
authors: Ke
authors: K
authors: Wang
authors: Ming Jing
authors: MJ
authors: Tu
authors: Yu Quan
authors: YQ
authors: Wei
authors: Zhi Yong
authors: ZY
authors: Qian
mesh_terms: D020341:Absorbable Implants; D001672:Biocompatible Materials / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D005782:Gels; D006358:Hot Temperature; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D008970:Molecular Weight; D011091:Polyesters / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D001672:Biocompatible Materials; D005782:Gels; D008823:Micelles; D011091:Polyesters; D012996:Solutions; C515340:poly(epsilon-caprolactone)-b-poly(ethyleneglycol)-b-poly(epsilon-caprolactone); D011092:Polyethylene Glycols