One-step approach to fabrication of PDA-PVA coatings with outstanding antifogging performance assisted by light illumination

Using clean and renewable solar energy, photothermal technology has garnered significant attention from researchers. Photothermal materials possess the capability to efficiently convert solar energy into thermal energy. In this work, polydopamine (PDA)- poly (vinyl alcohol) (PVA) coatings with outstanding antifogging performance assisted by light illumination were fabricated by a one-step scrape coating method at room temperature. PDA with excellent photothermal properties and strong adhesion to substrate was applied in combination with PVA as matrix. Carbon dots (CDs), which had previously been found as nano-crosslinkers to form abundant hydrogen bonds with hydroxyl groups of PVA and substrate, was used to enhance the mechanical robustness and the adhesion to substrate of coatings, producing a synergistic effect with the PDA. The coatings had an average transmittance exceeding 80 % in the visible region. Under xenon lamp with light intensities of 60, 80 and 100 mW cm −2 at the coating location, the temperature of the coating surface rose to 40.2, 46.1 and 53.1℃, respectively. Under xenon lamp with a light intensity of 100 mW cm −2 at the coating location, the antifogging duration when exposed to hot steam 5 cm above a 60 °C water bath was three times more than that without xenon lamp illumination. The coating remained unaffected even after immersion in water and various solvents for 2 h, without showing any signs of folding or damage. The coating exhibited a pencil hardness of up to 8 H and adhesion-to-substrate of up to 5 A, and was able to withstand the Taber wear test for 4000 cycles. The preparation method is simple and efficient, and may be applicable to a wide range of optical, optoelectronic, medical scenarios.