PLLA mesophase and its phase transition behavior in the PLLA-PEG-PLLA copolymer as revealed by infrared spectroscopy

Jianming Zhang, Yongxin Duan, Abraham J. Domb, Yukihiro Ozaki

Research output: Contribution to journalArticlepeer-review

117 Scopus citations

Abstract

A detailed analysis of the IR spectrum of melt-quenched PLLA-PEG-PLLA sample and its change with temperature is presented. It was found that, in the initial state of the melt-quenched PLLA-PEG-PLLA sample, the PLLA constituent does not exist as a normal amorphous or crystalline phase but as a kind of mesophase, which is confirmed by the WAXD data. The IR data suggest that both chain conformation and chain packing are disordered to some extent in such a mesophase. Therefore, this mesophase is less thermally stable than the ordered α phase and even the disordered α phase (α′) of PLLA. In the heating process, the mesophase of PLLA in the PLLA-PEG-PLLA copolymer starts the partial melt first upon heating in a stepwise way, and subsequently it is reorganized directly into the stable α phase but not through the α phase of PLLA. These phase transition behaviors are examined and discussed at the molecular functional group level.

Original languageEnglish
Pages (from-to)4240-4246
Number of pages7
JournalMacromolecules
Volume43
Issue number9
DOIs
StatePublished - 11 May 2010
Externally publishedYes

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