Photothermally induced scratch healing effects of thermoplastic nanocomposites with gold nanoparticles

A novel method for providing thermoplastic coatings with light-triggered self-healing ability is reported. Normal thermoplastic coatings can be healed efficiently via local heating generated by photothermal effect of gold nanoparticles (Au NPs). Small amounts of Au NPs were successfully dispersed into the coatings. Once the scratch occurred in the coating surface, a laser could be used to illuminate Au NPs to generate a large amount of heat which dramatically increased the local temperature through the photothermal effect. It would melt the polymer and form local deformation to merge the scratch efficiently. It had been confirmed that the coating containing Au NPs had the healing ability. After healing, the surface morphology and the mechanical property were recovered. The mechanism of the healing was also investigated and it was found that the Au NPs content and irradiation intensity played the key roles in the healing process. Through adjusting these two elements, the maximum temperature rise could achieve 225.5 °C. Healing tests were carried out on multiple types of thermoplastic coatings (PAA, PVAc, PS and TPU) and repeated healing was also achieved.