Fabrication of transparent super-hydrophilic coatings with self-cleaning and anti-fogging properties by using dendritic nano-silica

In this paper, super-hydrophilic coatings were generated on glass substrates via dipping method using colloidal silica with different morphologies as the main raw materials. The coatings were characterized by transmission electron microscope (TEM), field emission scanning electron microscope (FE-SEM), water contact angle (WCA) analyzer, and atomic force microscope (AFM). The hardness, adhesion, self-cleaning and antifogging properties of the coatings were examined. It has been found that the hydrophilicity of the coating can be significantly improved by using dendritic silica nanoparticles, and the comprehensive performance of the coating is optimum when the branch length of dendritic silica nanoparticles is about 60 nm. The coatings show super-hydrophilicity (CA, 1.7 degrees), and high transmittance (the maximum light transmittance of the coating on glass is increased by 2.2%). Moreover, the coating is very effective in eliminating fog and dirt. The hardness and the adhesion of the coating can be reached 9H and grade 0, respectively, indicating that the coatings have a good mechanical performance, which is essential for its application.