Thermal driven self-healing infrared and heat shielding composites based on reversible Diels-Alder reaction

Infrared and heat shielding materials have a wide range of applications in military infrared invisibility and thermal insulation for energy saving, but mechanical damage during use may reduce the service life. In this study, waterborne polyurethanes/gallium tin oxide (WPU/GTO) composites with good infrared and thermal shielding capabilities were fabricated after the introduction of GTO nanoparticles into the thermal driven self-healing WPU matrix. The results showed that the WPU/GTO composite films can show good healing efficiency through thermally reversible DA reactions, with a self-healing efficiency of 80 % in 30 min at 120 °C. In addition, the presence of GTO gives the composite good thermal shielding properties without affecting its thermal stability. Due to free carrier absorption and plasma reflection, the resulting composite films containing 1 wt% GTO could shield from approximately 95 % of infrared light, with an insulation temperature difference of 15 °C when compared to pure polyurethane. This work provides a feasible solution for the preparation of infrared and heat shielding materials with self-healing capabilities.