The surface with hydrophobic microstructure can be prepared by special treatment of the coating without other treatment. The preparation process is simple, and the coating can be carried out at the same time during the preparation process, which further simplifies the process. Inspired by lotus leaf, Ryu and Kim prepared a new microstructure (Lotus like) PDMS coating with high durability and relatively low friction coefficient. Unlike previously developed bio like coatings, microstructural PDMS samples can be fabricated as coatings and can be directly coated on solid surfaces (Fig. 2). Compared with smooth PDMS coating, the friction coefficient of microstructure PDMS coating is 2.5 times lower. After 5000 sliding cycle friction tests, the smooth PDMS coating surface was seriously damaged, but the lotus shaped PDMS surface showed no obvious signs of wear.

By spraying silicone oil (PDMS terminated by trimethylsiloxane) onto the glass plate heated to 550 ℃, a self-cleaning coating with superhydrophobic and excellent permeability can be obtained directly without additional solvent and surface treatment. The coating is stable at about 450 ℃, and it is not damaged in salt solution and pH value of 4 ~ 10 solution, and the coating has antifogging ability.

Zhou et al. Prepared large superhydrophobic PDMS coatings with high adhesion to water droplets by mold. The surface of the die was prepared by microfluidics and photopolymerization of N-isopropylacrylamide. The enhanced superhydrophobic surface has controllable surface morphology and wettability, which can be used for surface chemical transport.

By analyzing the application environment of the coating, the controlled surface treatment is a simple and effective method to prepare the self-cleaning coating, which does not need to add additional modifiers and complicated post-treatment steps. However, the surface treatment needs to be carried out on the micro scale, so it is necessary to choose a matching and effective treatment method. In the future, quantum chemistry and theoretical simulation may provide new tools for micro surface treatment.