Photo/thermoresponsive ABC triblock copolymer-based ion gels: photoinduced structural transitions

• Tamate, Ryota

• Usui, Ryoji

• Hashimoto, Kei

• Kitazawa, Yuzo

• Kokubo, Hisashi

• Watanabe, Masayoshi

Abstract

A photo/thermoresponsive ABC triblock copolymer-based ion gel exhibiting photoinduced structural transitions accompanied by significant rheological changes is newly developed. The ABC triblock copolymer comprises an ionic liquid (IL)-phobic A block, an IL-philic B block, and a photo/thermoresponsive C block containing azobenzene moieties. The IL-phobic A block forms a rigid micellar core in an IL over a wide temperature range and the photo/thermoresponsive C block undergoes upper critical solution temperature (UCST)-type phase transition in ILs. In concentrated polymer solution, the ABC triblock copolymer can form a percolated micellar network at low temperatures through aggregation of A and C blocks as physical crosslinks, bridged by IL-philic B blocks. In contrast, the ion gel undergoes structural transition to jammed micelles at high temperatures due to the disassembly of the thermoresponsive C block, resulting in significant softening of the ion gel. Importantly, the temperature dependences of the viscoelastic properties of the ion gel differ drastically depending on photo-irradiation conditions as the photoinduced isomerization of azobenzene moieties in the C block modulates the affinity between the polymer chain and IL. Utilizing this feature, photoinduced softening/hardening of the ion gel is realized at constant temperature. This study provides a promising strategy to control the rheological properties of nonvolatile soft materials via contactless light irradiation that could be exploited in various applications such as photoresponsive soft actuators and photo-healable soft materials.

Journal

• SOFT MATTER

  SOFT MATTER 14 9088-9095, 2018-12-05

  Royal Society of Chemistry

Keywords

• THIN-FILM TRANSISTORS
• POLYMER
• LIQUID
• HYDROGELS
• MICELLIZATION
• SPECTROSCOPY
• RELAXATION
• CHALLENGES
• MORPHOLOGY
• RHEOLOGY

Details

• CRID: 1050001337824588800
• NII Article ID: 120006545138
• ISSN: 1744683X
• ISSN: 17446848
• DOI: 10.1039/c8sm01578c
• Web Site: http://hdl.handle.net/10131/00012092
• Web Site: http://pubs.rsc.org/en/content/articlepdf/2018/SM/C8SM01578C
• Text Lang: en
• Article Type: journal article
• Data Source:
  • IRDB
  • Crossref
  • CiNii Articles
  • KAKEN