Illuminating Polymer Stress—The Innovative Use of Aggregachromic Fluorophores for Detection and Analysis

In a world where the use of plastics is becoming increasingly common in everyday life, the possibility of detecting damage and changes in properties of materials subjected to different surrounding environments becomes crucial. Therefore, interest in intelligent materials has increased drastically in recent years due to their ability to respond to an external stimulus through an optical output. Among all the accessible solutions to determine polymer damages, those involving the use of aggregachromic probes appear the most effective due to their high sensitivity, real-time monitoring capabilities, and the potential for non-destructive testing. Aggregachromic fluorophores exhibit unique photophysical properties, notably their fluorescence response to molecular aggregation. This characteristic makes them ideal candidates for sensing and probing various polymer behaviors under different conditions. Unlike conventional fluorophores, which often suffer from quenching when aggregated, aggregachromic fluorophores can either enhance (AIEE) or switch (AIE) their fluorescence emission. This unique behavior is leveraged in various sensing applications, including the detection of mechanical, thermal, and chemical stimuli in polymeric materials. In this contribution, we report the use of different aggregachromic AIEE and AIE fluorophores to monitor mechanical and thermal solicitations. Notably, when a polymer composite embedded with these fluorophores is subjected to mechanical stress, the resultant aggregation changes provide a fluorescent signal corresponding to the level of strain or stress. This application is crucial in structural monitoring, where real-time detection of mechanical damage can prevent catastrophic failures. In addition, the response of aggregachromic fluorophores to thermal changes in polymers can be used to detect temperature variations and phase transitions. These fluorophores can indicate melting, crystallization, or thermal degradation processes within polymeric materials, making them valuable in the thermal management and quality control of polymer products. Continued research and development in this area hold promise for advancing polymer science and expanding the applications of these innovative materials in numerous industrial and scientific fields.