Transparent superhydrophobic films possessing high thermal stability and improved moisture resistance from the deposition of MTMS-based aerogels

Highly transparent superhydrophobic silica aerogel films with high water contact angle (>160°) and low sliding angle (<5°) were prepared by using methyltrimethoxysilane (MTMS) as precursor based on a simple sol–gel process. The influences of different solvent amount on the superhydrophobicity, transparency, microstructure, N2 adsorption–desorption behavior and pore size distribution of as-prepared films were discussed herein to get the film with optimum performance. The optimum film exhibits superhydrophobicity (CA, 161° and SA, 4°), high transparency (transmittance closes to 90%) and good thermal stability (up to 500 °C). Note that the optimum film directly from sol–gel process exhibits poor moisture resistance. The low density, high volume-fraction porosity structure and methyl groups on the surface are the cause of superhydrophobicity of the film. Low density and high volume-fraction porosity structure are also responsible for the thermal stability of the as-prepared film, and the poor moisture resistance is ascribed to the untreated hydroxyl groups on the surface of the film. The moisture resistance of film can be improved by further treatment with cetyltrimethoxysilane (CTMS). The film switches from superhydrophobic (161°) to superhydrophilic (0°) after heat-treated at 600 °C.