Bioinspired Healable Mechanochromic Function from Fluorescent Polyurethane Composite Film

Graphical Smart polymers : Bioinspired healable mechanochromic (HMC) materials from synthesized fluorescent polyurethane film is constructed. The mechanochromic function of the HMC materials is tunable from the hierarchical bilayer nanostructures. In addition, the broken mechanochromic function of HMC materials can be almost restored at a mild condition for high level of information encryption. Camouflage and wound healing are two vital functions for cephalopods to survive from dangerous ocean risks. Inspired by these dual functions, herein, we report a new type of healable mechanochromic (HMC) material. The bifunctional HMC material consists of two tightly bonded layers. One layer is composed of polyvinyl alcohol (PVA) and titanium dioxide (TiO 2 ) for shielding. Another layer contains supramolecular hydrogen bonding polymers and fluorochromes for healing. The as-synthesized HMC material exhibits a tunable and reversible mechanochromic function due to the strain-induced surface structure of composite film. The mechanochromic function can be further restored after damage because of the incorporated healable polyurethane. The healing efficiency of the damaged HMC materials can even reach 98 % at 60 °C for 6 h. The bioinspired HMC material is expected to have potential applications in the information encryption and flexible displays.