Achieving room-temperature self-healing of mechanoluminescent materials by dynamic borate ester bonding

The mechanoluminescent (ML) stress sensing technology based on a unique mechano-to-photon conversion principle has exhibited great potentials in fields of flexible electronics, structural health diagnosis, biomechanical engineering, and self-powered displays. However, a big challenge for the ML sensing technology is that ML sensing materials with a typical inorganics@organics structure will be damaged when the applied mechanical load exceeds its strength limit, which thus reduces the reliability and durability of the sensing system. Herein, we propose a self-healing method to solve the failure of sensing materials by constructing a polyborosiloxane/ polydimethylsiloxane (PBS/PDMS) dual-network structure. The dynamic borate ester bonding in the PBS network provides self-healing capability, and the chemically crosslinked PDMS network enables the ML materials to maintain good elasticity and structural stability. The mechanical properties and ML properties of the dual-network material can be effectively restored even after fatal fracture, with a 75% recovery rate in tensile strength and nearly 100% recovery of mechano-to-photon conversion efficiency after 10 min at room temperature. The self-healing ML materials allow to greatly promote the applications of ML technologies for complex, high-strength and flexible stress sensing.