Reversible mechanochromism of a luminescent elastomer

A novel mechanochromic elastomer was manufactured by doping bis(benzoxazolyl)stibene (BBS) into a thermoplastic polyurethane. Both solution casting and melt compounding approaches were tried with a range of BBS concentrations, and an optimal concentration of 0.5% was selected to investigate the mechanochromic mechanism in detail. When the blend film was stretched up to 100%, its emission peaks at 475 and 413 nm changed in intensity ratio from 6.3 to 1.8. When it was released, both the film size and emission peaks largely recovered. By a short annealing at 120 °C, their full recovery was achieved. Its reversion mechanism was proposed and proved by X-ray diffraction. In comparison to previous mechanochromic materials, this smart elastomer is easy to prepare, highly sensitive to stress, facilely renewable in usage, and totally based on biocompatible materials, having potential applications like stress sensors, intelligent devices, and alarming packages.