LAUSR

Abstract Cracks generated in materials affect comprehensive performance and shorten service life of materials. The problem is expected to be resolved by endowing materials with self-healing property. Herein, a new thermoplastic polyurethane with excellent self-healing performance (PU-DA) has been developed, while the self-healing behavior is investigated by qualitative observation and quantitative measuring comparatively. Results reveal that PU-DA exhibits excellent thermal reversibility due to incorporated Diels-Alder (DA) bonds, and cracks in polyurethane films can be repaired by dual actions of thermo-reversible DA reaction and thermal movement of molecular chains. DA bond and its thermal reversibility contribute much to the recovery of the mechanical property while the thermal movement effect of molecular chains acts as an auxiliary recovering force which accelerates the whole healing process. The self-healing behavior of PU-DAs from diverse soft segments and different -NCO/-OH values further confirms that the excellent self-healing performance is grounded on combined actions indeed. Additionally, the self-healing polyurethane presents outstanding reprocessing performance, and which makes it possible of recycling waste polyurethanes. This study enables the re-demonstration of general points about DA thermal reversibility already known, as well as presentation of link between self-healing capability and thermal reversibility along with thermal movement.