Facile casting preparation of hydrophilic coordinated PVA–Zn ion coatings with strong adhesion and high water tolerance

Fogging on transparent surfaces may severely influence vision. Thus, antifogging coatings are in high demand. Poly vinyl alcohol (PVA) and zinc chloride were mixed to prepare hydrophilic coatings (denoted as PVA/Zn2+ coatings) on glass substrates using the casting method with contact angles <59°. The polymer-metal complex was formed by the coordination of ZnCl2 with the hydroxyl groups of PVA. The adhesion and water resistance of the coating were improved by adjusting the mole ratio of PVA to Zn2+. A 5B adhesion grade of the optimal mole ratio of PVA to Zn2+ was determined according to the standard of the American Society of Testing Materials D3359, and the lap shear strength was 2.39 ± 0.42 MPa. The coordination between OH and Zn2+ was evidenced by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. UV–vis spectra show that the coating has a high optical transmittance (>90 %). In addition, the coating was applied on four common hydrophobic substrate surfaces to obtain hydrophilic surfaces. The antifogging performance of the coating indicates its potential application to many materials such as in transparent optical devices.