Dual photochromic/mechanochromic responses of self-healing cellulose-based film for anti-counterfeiting and damage warning

Abstract

It is challenging to develop novel dual stimuli-responsive materials with synergetic color-switching responses and outstanding self-healing properties. Herein, a novel cellulose-based photochromic and mechanochromic film was prepared by a facile synthesis process. The photochromic and mechanochromic responses not only exhibited various color transitions in response to different stimuli but also synergized with each other. In particular, the color of the mechanochromic response changed from purpleness to whiteness under ultraviolet light, which differs from the color transition from yellowness to whiteness under visible light. The uninterrupted and synergistic responses were attractive for applications in anti-counterfeiting and damage warning. Moreover, the dual stimuli-responsive material balanced the comprehensive properties. The optimized sample has high stretchability (1100 %), excellent cyclic stretch-relax performance (higher than 30 times at strain of 400 %), superior self-healing properties (2 h of healing at room temperature), and good shape memory behavior (shape recovery ratio of 97.5 %). Above all, the dual stimuli-responsive material combined photochromic and mechanochromic responses with high stretchability, excellent repeatability, outstanding self-healing property, and good shape memory behavior, demonstrating the great potential for applications in anti-counterfeiting, damage warning, and flexible wearable devices.