Recovering mechanoluminescence in SAOED/epoxy stress sensors with self-healing epoxy vitrimers

Abstract

In mechanoluminescence stress sensors, understanding the relationship between light emission performance and sensor structural stability is crucial to ensure the accuracy, sensitivity, and reliability of stress sensing during operation. Any minor structural damage or debonding at the particle–epoxy interface will reduce stress transfer capacity and hamper the light emission from SAOED particles. Instead of replacing the sensors with reduced light emission performance, self-healing epoxy vitrimers can open up new opportunities for recovering mechanoluminescence, offering durable and environmentally friendly high-performance stress sensors. This study investigates two epoxy vitrimer systems for ML stress sensors compared to commercial epoxy. Siloxane bond exchange-based ML stress sensors are found to be promising in terms of light intensity, stress sensitivity, and ML recovery. Exposing sensors to a thermal treatment revealed an increase in light intensity, which is associated with a temperature effect on SAOED particles and self-healing bond exchange in dynamic epoxy networks.