Hydrophilic Coating With Anti-fogging and Anti-icing Properties

Hydrophilic coatings were prepared by dip-coating bare glass in polyvinylpyrrolidone (PVP)/silicon dioxide (SiO₂) or polyvinylpyrrolidone (PVP)/carboxybetaine acrylamide (CBAA) suspensions. The effects of surface wettability on the anti-fogging and anti-icing properties of the two coatings were investigated. The surface morphologies of the coatings were characterized by polarized light microscopy and laser confocal microscopy, and the hydrophilicity of the coatings depended on the binding capacity of the hydrophilic functional groups in the fillers with water. The wettability of the coating surface was characterized by contact angle measurements, and it improved with increasing filler content. The coatings with the addition of more than 80 wt % of SiO₂ or 1 wt % of CBAA showed superhydrophilic behavior. The anti-fogging and anti-frosting test results showed that the two coatings successfully prevented the development of fog and frost. The anti-icing properties of the coatings were also characterized. At three different temperatures, the anti-icing performance of the CBAA coating was better than that of the SiO₂ coating. For, instance, at −15 °C, the icing delay time of PVP/SiO₂ coating was 306.7 s and that of PVP/CBAA coating was 630.0s. Thus, the icing time of the CBAA coating was 323.3s longer than that of the SiO₂ coating. When less than 80 wt% SiO₂ or 10 wt% CBAA was added, the coating had good transparency.