Dual-responsive graphene hybrid structural color hydrogels as visually electrical skins

Stimuli-responsive materials have been experiencing explosive developments, which are functionally integrated with multi-signals in response to external environment variations. Here, we present a novel dual-responsive graphene hybrid structural color film as electronic skins. The film is fabricated by adding conductive reduced graphene oxide (rGO)-poly(N-isopropylacrylamide) (PNIPAM) filler into a poly(ethyleneglycol) diacrylate (PEGDA) inverse opal scaffold. The inverse opal scaffold imparts the film with brilliant structural color and the addition of rGO endows the hybrid film with excellent conductivity. Because of the temperature response adjustability of the PNIPAM polymer, the resultant film is capable of changing volume or internal nanostructure under temperature stimuli. In addition, benefiting from the extraordinary near-infrared (NIR) photo-thermal transformation property of rGO, such hybrid films with temperature-sensitive polymer components could be introduced with photo-responsive properties. Based on these features, the hybrid film could not only feed electrical signals back, but also exhibit color changes visually when responding to the temperature and NIR stimuli. Furthermore, the value of the hybrid film on electro-thermal conversions has been explored. These features indicate that the hybrid conductive structural color films possess the promising application prospects in flexible electronics.