Waterborne Polyurethane Transparent Coatings for Self-Healing at Room Temperature

Waterborne polyurethanes are now widely used for preparing adhesives and coatings. They are considered as a sustainable alternative for solvent-borne applications because of reductions in volatile organic compounds (VOC) emissions. However, imparting a property of self-healing at room temperature to these polyurethanes remains challenging. Herein, we synthesized prepolymers containing thiosulfate groups, which enabled their dispersibility in aqueous solutions. The thiosulfate groups were subsequently hydrolyzed to form disulfide bonds. Recovery of mechanical and optical properties (transmittance) at room temperature was then observed due to dynamic disulfide exchange reactions.