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Controlled Sol–Gel Transitions of a Thermoresponsive Polymer in a Photoswitchable Azobenzene Ionic Liquid as a Molecular Trigger
Author(s) -
Wang Caihong,
Hashimoto Kei,
Tamate Ryota,
Kokubo Hisashi,
Watanabe Masayoshi
Publication year - 2018
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.201710288
Subject(s) - azobenzene , photoisomerization , polymer , materials science , ionic liquid , methacrylate , copolymer , methyl methacrylate , polymer chemistry , thermoresponsive polymers in chromatography , ionic bonding , chemical engineering , isomerization , chemistry , organic chemistry , phase (matter) , catalysis , composite material , ion , reversed phase chromatography , engineering
Producing ionic liquids (ILs) that function as molecular trigger for macroscopic change is a challenging issue. Photoisomerization of an azobenzene IL at the molecular level evokes a macroscopic response (light‐controlled mechanical sol–gel transitions) for ABA triblock copolymer solutions. The A endblocks, poly(2‐phenylethyl methacrylate), show a lower critical solution temperature in the IL mixture containing azobenzene, while the B midblock, poly(methyl methacrylate), is compatible with the mixture. In a concentrated polymer solution, different gelation temperatures were observed in it under dark and UV conditions. Light‐controlled sol–gel transitions were achieved by a photoresponsive solubility change of the A endblocks upon photoisomerization of the azobenzene IL. Therefore, an azobenzene IL as a molecular switch can tune the self‐assembly of a thermoresponsive polymer, leading to macroscopic light‐controlled sol–gel transitions.