Healable soft materials based on ionic liquids and block copolymer self-assembly

Abstract

Ion gels, which are macromolecular networks filled with ionic liquids, are attracting significant interest owing to their unique physicochemical properties such as their nonflammability, negligibly low volatility, and high ionic conductivity. However, for greater applicability in electrochemical devices, these materials must have high mechanical strength while continuing to exhibit the desirable properties of ionic liquids. Therefore, functional ion gels that can self-heal in response to external stimuli or in an autonomous fashion are being investigated. In this review, we highlight the recent progress made by our group in the development of healable ion gels formed by the self-assembly of block copolymers in ionic liquids. First, photohealable ion gels that exploit the photoinduced morphological transitions of block copolymers in ionic liquids are described. Then, the molecular design of self-healing block copolymer-ion gels that show fast self-healing as well as high mechanical strength is discussed. Our recent development on healable soft materials that utilize block copolymer self-assembly in ionic liquids is reviewed. We begin by discussing photohealable ion gels that respond to specific wavelength of light irradiation by forming and collapsing stimuli-responsive networks. Then, we highlight on the self-healing ion gels based on synergetic combination of supramolecular interaction and block copolymer self-assembly, which realize high mechanical strength and fast self-healing ability in the absence of any external stimuli.