Mechanically robust multifunctional antifogging coating on transparent plastic substrates

A facile preparation method to form a transparent self-cleaning antifogging coating on polycarbonate substrates is reported. The coating uses a thin double layered SiO2/TiO2 structure, which has an additional advantage of reduced visible light reflection. A two-step protocol is developed for enhanced mechanical durability, which comprises a room temperature oxygen plasma treatment of the polycarbonate substrate, followed by deposition of the SiO2/TiO2 films using pulse laser deposition. The oxygen plasma treatment changes the polymer surface chemistry to allow strong adhesion with the antifogging coatings. The SiO2/TiO2 coating exhibits superhydrophilicity even without the previously claimed necessary ultraviolet irradiation. The self-cleaning capability is demonstrated via photocatalytic degradation of methylene blue and oleic acid. Excellent adhesion and mechanical robustness of the coating is exhibited by crosshatch and abrasion tests. The multifunctional coating on polymer substrates provides an avenue for practical applications for optical lenses and displays.