Preparation and properties of water-responsive films with color controllable based on liquid crystal and poly(ethylene glycol) interpenetrating polymer network

Stimuli-responsive materials have been extensively studied due to their potential in environmental detection and information encryption. In this work, a water-responsive film based on cholesteric liquid crystal (CLC) and polyethylene glycol (PEG) interpenetrating polymer network (IPN) was designed and prepared. When humidity of the surrounding environment changed, the film can reversibly change colour due to the absorption and desorption of water molecules. Compared with the water-responsive films that have been reported now, the step of alkali treatment was eliminated and the damage of the film structure was avoided. More importantly, the factors affecting performances of the IPN film were investigated in detail. By changing these factors, the water-responsive IPN film with different performances can be obtained, implying the unique advantage of this novel film in performance control. Finally, a patterned water-responsive IPN film was designed and prepared using a photomask, demonstrating the potential applications of the intelligent IPN films in information encryption and environmental detection.