Robust Poly(urethane-amide) Protective Film with Fast Self-Healing at Room Temperature

Simultaneous optimization of the mechanical strength and self-healing cycles of polymers at ambient temperature has long been considered a great challenge because it is difficult to strike a balance between intermolecular interactions and segment/chain mobility. Here, we synthesized a unique class of amide-based polyurethanes incorporated with an unreported low-cost carboxylic-acid-type aromatic disulfide, which exhibits an amazing integration of mechanical robustness and fast self-healing ability, and a ready healing efficiency of 98% can be achieved when healed for only 30 s at ambient temperature, as calculated using Young’s modulus (pristine: 59.4 MPa). As a result of hierarchical structure tuning, the target poly­(urethane-amide) exhibits relatively fast segment movements but slow chain diffusion dynamics, thus facilitating rapid recombination of H-bonding as well as disulfide metathesis between fractured surfaces with a small degree of both microphase separation and crystallization. This easily processable poly­(urethane-amide) has the potential to be widely used in various industries as a high value-added film.