Spiropyran-incorporated honeycomb porous films with reversible multistimuli-responsive properties

Abstract

A spiropyran (SP)-incorporated honeycomb-structured porous film which combines the attractive features of a honeycomb-patterned porous structure with the excellent stimulus responsiveness of SP was successfully prepared using the simple, low-cost and environmentally friendly static breath figure method. Reversible variations in UV absorption and color of the porous film's response to UV light, heating and pH were found, demonstrating their photo-, thermo- and acido-chromic properties that benefit from the isomerization of the doped SP. A stronger and faster response was verified for the honeycomb porous film compared to the flat one through analyzing their isomerization kinetics, confirming the superiority of the honeycomb structure in stimuli-responsive materials. In addition, good photo-/thermo-fatigue resistance of the honeycomb film was observed illustrating the maintenance of the photo/thermal-stability, photo/thermal-switchability and reversibility of the doped SP. Overall, based on the responsiveness of the film color and properties to light, heat and pH, the applications of the SP-incorporated honeycomb film in acid vapor detection, photo/thermo-driven rewritable patterns, information decryption and encryption, molecular logic gates, wettability regulation and milk spoilage detection were realized.