Hydrogen-Bonding-Driven Tough Ionogels Containing\nSpiropyran-Functionalized Ionic Liquids

Abstract

Smart control of\nthe physicochemical properties of ionogels is\nparamount for on-demand applications. However, the development of\nmechanically robust smart ionogels prepared from stimuli-responsive\nionic liquids (ILs) still remains a considerable challenge. Here,\nwe report light-responsive tough ionogels driven by hydrogen bonding\nbetween spiropyran-functionalized ILs and poly­(ethyl acrylate)-based\ndouble networks. The designed ionogel possesses excellent mechanical\nproperties (moderate elastic modulus of ∼524 kPa, large stretchability\nof ∼2880% strain, and high toughness of ∼46.4 MJ m^–3). Moreover, the ionogel exhibits rapid and obvious\ncolor changes upon UV- and visible-light irradiation, resulting from\nthe reversible structural transformation between spiropyran and merocyanine\nforms of the IL dispersant. This feature enables reversible photopatterning\non the ionogel that can be written and erased upon photoirradiation.\nWe envision that the light-responsive tough ionogels could have potential\napplications in optical data storage and photoswitchable devices.