Hydrophilic surface-assisted thermoresponsive smart window based on lower critical solution temperature (LCST)-type phase separation

We investigate the effect of an atmospheric pressure plasma treatment on a thermoresponsive ionic liquid device, which exhibits lower critical solution temperature (LCST)-type phase separation. The opaque state for the ionic liquid device with a polyimide treated by the atmospheric pressure plasma was dramatically stabilized, because H2O microdroplets were pinned onto the polyimide. This surface-assisted stabilization originated from a hydrophilic interaction, such as hydrogen bonds between H2O droplets and various oxygen-containing functional groups at the polyimide surface, which was generated by the atmospheric pressure plasma. This unique technique is expected to develop information display devices whose function is driven by temperature.