A thermal self-healing polyurethane thermoset based on phenolic urethane

Thermosetting polyurethanes have excellent elastic properties and solvent resistance, but they cannot be reshaped like thermoplastic polymers after molding. In this study, we designed a thermosetting polyurethane based on a reversible reaction between isocyanates and phenolic hydroxyls instead of alcoholic hydroxyls. The phenolic urethane partially decomposed above 120 °C, but the phenolic hydroxyl and isocyanate groups reconnected upon cooling. These reversible urethane bonds contributed to the thermal self-repair of the thermosetting polyurethane network. This thermosetting elastomer was organic-insoluble below 120 °C. Compared to the original material, the healed thermoset preserved approximately 70% of its tensile strength and exhibited 86% elongation at break. This thermosetting polyurethane can be applied in self-healing coatings or adhesives.