Hierarchical Sol-Gel Transition Induced by Thermosensitive Self-Assembly of an ABC Triblock Polymer in an Ionic Liquid

Yuzo Kitazawa, Takeshi Ueki, Lucas D. McIntosh, Saki Tamura, Kazuyuki Niitsuma, Satoru Imaizumi, Timothy P. Lodge, Masayoshi Watanabe

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Abstract

We investigated a hierarchical morphology change and accompanying sol-gel transition using a doubly thermosensitive ABC-triblock copolymer in an ionic liquid (IL). The triblock copolymer contains two different lower critical solution temperature (LCST) thermosensitive polymers, poly(benzyl methacrylate) (PBnMA) and poly(2-phenylethyl methacrylate) (PPhEtMA), as the end blocks and poly(methyl methacrylate) (PMMA) as the middle block (PBnMA-b-PMMA-b-PPhEtMA: BMP). BMP undergoes a hierarchical phase transition corresponding to the self-assembly of each of the thermosensitive blocks in the IL, and a sol-gel transition was observed in concentrated, above 10 wt %, polymer solutions. The gelation behavior was affected by polymer concentration, and at 20 wt %, the BMP/IL composite showed a phase transition, with increasing temperature, from solution through a jammed micelle suspension to a physically cross-linked gel. Each phase was formed reversibly and rapidly over the corresponding temperature range. The jammed micelle and cross-linked gel states were characterized using viscoelastic measurements and small-angle X-ray scattering (SAXS).

Original languageEnglish (US)
Pages (from-to)1414-1423
Number of pages10
JournalMacromolecules
Volume49
Issue number4
DOIs
StatePublished - Mar 8 2016

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