Fabrication and Characterization of Mineral Hydrophilic Antifogging Film via Vacuum Evaporation Method

Natural silicate minerals have a wide range of applications as green, non-toxic and low-cost materials. In this paper, hydrophilic anti-fog films of silicate minerals were generated via a vacuum evaporation coating method using natural feldspar minerals as raw material. Thermogravimetric analysis shows that the feldspar changes its structure during the coating process, which in turn changes the roughness of the film and improves the hydrophilicity of the film. The hydrophilicity, anti-fogging properties, optical properties and surface morphology of the films were characterized by contact angle measurements, the hydrothermal method, UV-VIS spectrophotometer and atomic force microscopy, respectively. The results show that the mineral films have excellent hydrophilicity. The best anti-fog effect was achieved at a minimum contact angle of 22.3° with water when the thickness of the film was 100 nm. The anti-fog effect gradually decreased with the increasing thickness of the film. The optical transmittance test showed that the film material had a negligible effect on the transmittance of the substrate. When the film thickness was 100 nm, the maximum optical transmittance was 92.2%. This is 4.5% higher than when the film was uncoated, which has a specific visual transmittance effect.