Self-Healing and Fluorescent Carbon Dot-Embedded Polylactic Acid–Based Polyurethane (PLA–PU) Composites for Enhanced Mechanical and Diagnostic Applications

Potential applications of great significance encompass bioimaging, drug delivery, fluorescence sensing, and photocatalysis, wherein CDs can excel due to their distinctive optical properties and environmental compatibility. Conversely, CDs in solutions often exhibit instability and their fluorescence is frequently quenched by aggregation phenomena and interactions with dissolved oxygen, thereby limiting their practical applications. To mitigate these challenges, an innovative encapsulation method was devised by incorporating CDs into a biodegradable poly(lactic acid)-based polyurethane matrix via a Schiff base reaction, thereby enhancing their stability and optical properties. Characterization outcomes demonstrate that the CDs@PU composite exhibits robust fluorescence retention, self-healing capabilities, and enhanced mechanical durability. Fluorescence-based active damage detection tests substantiate autonomous active damage sensing and self-repair functionalities. The study delineates how the developed material could offer a durable and multifunctional composite, which is particularly valuable for sustainable diagnostic and self-healing applications.