Rapid self-healing in IR-responsive plasmonic indium tin oxide/polyketone nanocomposites

Rapid self-healing materials are highly demanded to decrease polymer pollution and increase the material’s service life. In this work, we designed a self-healing thermo-responsive nanocomposite containing homogeneously dispersed indium tin oxide (ITO) nanocrystals (NCs). ITO NCs were used as an infrared photothermal source owing to their outstanding near-infrared plasmonic properties and visible transparency. As a polymer matrix, a furan grafted polyketone (PKFU) was prepared via Paal–Knorr functionalization and crosslinked with an aromatic bismaleimide via the Diels–Alder (DA) reaction. Nanocomposites containing the 0.4, 0.9, and 1.5 wt% of ITO NCs showed strong absorption between 1500 and 2250 nm and once exposed to a cheap IR lamp, they showed rapid heating up to temperatures >160 °C within 30 seconds, compared to around 60 °C for the bare polymer. The addition of ITO NCs did not affect the thermal behaviour of the matrix with the retro-Diels–Alder onset above 95 °C and the softening point at 50 °C, which effectively enabled the healing process. Remarkably, the nanocomposite with 0.9 wt% of ITO NCs showed the fastest healing rate: healing occurs after 1 second of IR irradiation, compared to the 50 seconds required for the bare thermoset matrix.