Thermal/NIR activated self-healing polyurethane with shape memory toward multi-level encryption

Stimulus-responsive fluorescent materials have attracted widespread attention in information encryption. However, the development of versatile, tough, self-healing fluorescent anti-counterfeiting materials with high confidentiality remains a formidable challenge. Herein, we present a shape-memory self-healing fluorescent polyurethane (HFPU) for the construction of a multi-level information encryption platform. The internal microphase-separated structure, along with abundant hydrogen bonds and disulfide bonds interactions, endows HFPU with excellent toughness (138.2 MJ/m 3 ) and rapid self-healing capability (90.3 %) under thermal excitation. The HFPU backbone incorporates 4-[2-(4-hydroxyphenyl)-1,2-diphenylethenyl]phenol (HPPE) units, which exhibit aggregation-induced emission (AIE) during solid-state aggregation, enabling the encryption of screen-printed two-dimensional (2D) fluorescence patterns. Furthermore, MXene as a photothermal filler, was introduced into HFPU to realize the remote non-invasive triggering of shape memory and the self-healing process via NIR light. The shape memory behavior enables the concealment of 2D fluorescence information via three-dimensional (3D) structural transformations, facilitating multi-level and multidimensional information storage and encryption. This study provides a feasible strategy for the development of smart anti-counterfeiting materials with long lifespan and enhanced information security.