Shape-Memory–Assisted Self-Healing and Real-Time Acidic Environment Detection in Multifunctional Electrospun Fibers

Smart fiber systems that integrate self-healing and environmental responsiveness are emerging as promising candidates for wearable electronics, protective clothing, and adaptive textiles. Here, we report a multifunctional electrospun fiber platform combining shape-memory-assisted self-healing with acid-triggered chromism. The fibers are fabricated from thermoplastic polyurethane (TPU)/poly(ε-caprolactone) (PCL) blends doped with the acid-sensitive dye ODB-2. Distinct thermal transitions of TPU and PCL enable programmable deformation and recovery, whereby fractured fibers self-heal through thermally activated interfacial diffusion. Meanwhile, ODB-2 undergoes a reversible structural change upon protonation, producing a visible color contrast that functions as an acid-responsive optical signal. Systematic characterization of chemical structure, morphology, and functional performance reveals a clear compositional dependence. TPU-rich blends yield uniform fiber morphologies, stable chromic reversibility over multiple acid-base cycles, and self-healing efficiencies up to 95%. In contrast, PCL-rich compositions exhibit larger fiber diameters, reduced chromic response, and incomplete mechanical recovery. These results demonstrate how polymer composition governs both structural features and functional outcomes. By integrating shape-memory, self-healing, and chromic responsiveness into a single platform, this work establishes a versatile design strategy for smart polymer fibers capable of damage repair and real-time environmental monitoring. The approach offers broad opportunities for developing next-generation wearable electronics, intelligent textiles, and adaptive membranes for use in corrosive or dynamically fluctuating environments.