Multi-functional fluorescent silicon elastomer cross-linked with AIE polymer by dynamic imine bond and its application in anti-counterfeiting

Fluorescent elastomer materials have received extensive attention due to their excellent optical performance, flexibility, and chemical stability in recent years, and demonstrate great application potentials in intelligent sensors, optoelectronic devices, medical equipment and other fields. Although the traditional method for constructing fluorescent elastomers by doping fluorescent small molecules is facile and universal, it also has limitations such as low luminous efficiency, uneven dispersion, poor stability and single function. In this work, an aggregation-induced emission (AIE) fluorescent polymer with aldehyde groups in side chain was synthesized and crosslinked with aminopropyl double capped polydimethylsiloxane (NH2-PDMS-NH2) through mild Schiff base reaction to construct a fluorescent elastomer. Compared with fluorescent small molecules, AIE polymers have superior fluorescence performance and can be flexibly designed according to demands. The dynamic imine bonds endow the as-obtained elastomers with self-healing and recycling properties, enabling rapid repair and remodeling at room temperature. Besides, the tensile and swelling properties of PDMS enable them to adjust the concentration of fluorescent units in the matrix under corresponding stimulus, thereby achieving tunable fluorescence emission. Taking advantage of the fluorescent elastomers, we prepared fluorescent anti-counterfeiting patterns that were hidden in daylight and visible under UV light, demonstrating the potential applications of the fluorescent elastomers in the fields of anti-counterfeiting and information encryption. This study also provides an alternative strategy for developing multifunctional fluorescent elastomers.