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Photoreversible Gelation of a Triblock Copolymer in an Ionic Liquid
Author(s) -
Ueki Takeshi,
Nakamura Yutaro,
Usui Ryoji,
Kitazawa Yuzo,
So Soonyong,
Lodge Timothy P.,
Watanabe Masayoshi
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201411526
Subject(s) - copolymer , micelle , ethylene oxide , polymer chemistry , azobenzene , ionic liquid , materials science , methacrylate , hexafluorophosphate , polymer , bistability , ionic bonding , chemical engineering , chemistry , organic chemistry , ion , catalysis , optoelectronics , aqueous solution , composite material , engineering
The reversible micellization and sol–gel transition of block copolymer solutions in an ionic liquid (IL) triggered by a photostimulus is described. The ABA triblock copolymer employed, denoted P(AzoMA‐r‐NIPAm)‐b‐PEO‐b‐P(AzoMA‐r‐NIPAm)), has a B block composed of an IL‐soluble poly(ethylene oxide) (PEO). The A block consists of a random copolymer including thermosensitive N‐isopropylacrylamide (NIPAm) units and a methacrylate with an azobenzene chromophore in the side chain (AzoMA). A phototriggered reversible unimer‐to‐micelle transition of a dilute ABA triblock copolymer (1 wt %) was observed in an IL, 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([C 4 mim]PF 6 ), at an intermediate “bistable” temperature (50 °C). The system underwent a reversible sol–gel transition cycle at the bistable temperature (53 °C), with reversible association/fragmentation of the polymer network resulting from the phototriggered self‐assembly of the ABA triblock copolymer (20 wt %) in [C 4 mim]PF 6 .