Preparation and characterization of polyurethane-SiO₂ composite super-hydrophilic transparent coating with self-cleaning and anti-fog

Glass curtain is foggy and difficult to clean, which increases the cost of wall maintenance. The water-borne polyurethane(PU), hydrophilic SiO₂, tetraethyl orthosilicate(TEOS) and ethanol were used as basic materials, and the PU-SiO₂ coatings were sprayed on glass curtain wall by spraying process. After curing at room temperature, a transparent PU-SiO₂ coating with good wear resistance and fog resistance could be obtained. The surface morphology of the PU-SiO₂ coatings was characterized by SEM and the causes of surface wettability were explored through comparative experiments. The principle of superhydrophilicity of the PU-SiO₂ coatings was analyzed. The results of wear resistance and fog resistance test show that the PU-SiO₂ coating can withstand the maximum pressure of about 26 kPa and has good fog resistance. Ultraviolet-visible spectrophotometer test results show that the PU-SiO₂ coating has good transparency. The outdoor experiment shows that the PU-SiO₂ coating has good weatherability. The method used in this paper solves the problems of complex process and environmental protection of existing methods, and can be directly applied to the glass curtain wall surface of existing buildings.