Dual-crosslinked polyurethane elastomers based on diselenide bonds and strain-induced crystallization for high elasticity, self-healing, and strain/temperature-responsive sensing

Thermoplastic polyurethane elastomers (TPUs) have been increasingly applied in soft robotics and flexible electronics. However, conventional TPUs often exhibit limited thermal stability and poor interfacial fatigue resistance, and single reinforcement strategies are insufficient to achieve a balanced enhancement of strength, elasticity, and thermal stability. In this study, we propose a dual-crosslinking strategy coupled with strain-induced crystallization to address these challenges. Poly(ε-caprolactone) diol (PCL) is incorporated into the polyurethane backbone, enabling the formation of a crystalline reinforcement phase under deformation. A covalent network is formed via the polyaddition of trimethylolpropane (TMP) and isocyanate groups (-NCO), while the incorporation of 2-(1-hydroxyethyl) diselenide (DiSe-DiOH) introduces a dynamically reversible diselenide network, together producing a double-crosslinked structure. The resulting polyurethane elastomer (DiSe-PU) exhibits outstanding overall performance, including high tensile strength (18.31 MPa), large elongation at break (1881%), high toughness (114.46 MJ/m 3 ), and good thermal stability (Td 5%  = 280 °C). It also exhibits controllable self-healing behavior, achieving stress and strain healing efficiencies of 66.67% and 98.25%, respectively, when activated by ethanol and further promoted by heating. Furthermore, a flexible sensor fabricated by integrating DiSe-PU with the ionic liquid [EMIm][TFSI] demonstrates dual strain and temperature responsiveness, achieving a gauge factor of 0.41 and a temperature coefficient of resistance of −0.02 °C −1 . This work offers an effective strategy for developing high-performance, self-healing, multifunctional polyurethane elastomers.