A robust method for the development of mechanically, thermally stable anti-reflective and self-cleaning coatings through in-situ formation of hierarchical raspberry-like mesoporous nanoparticles

Abstract

A robust formulation was developed to produce anti-reflective and self-cleaning coatings, consisting of hierarchical mesoporous silica, modified mesoporous titania nanoparticles and siloxane resin along with other ingredients. The hierarchical arrangement of nanoparticles by the process of self-assembly along with the polymerization of resin developed hierarchical micro and nanoscale structure on the coated surface because of the in-situ generation of raspberry-like particles during film formation. A systematic study was carried out to investigate the effect of additives on the microstructure, optical property and wettability of the coatings. The optimum composition of the coating has anti-reflective property with maximum transmittance of 99.6% (364 nm) with an absolute increase in transmittance of 5.3% in the wavelength range of 360–600 nm with a contact angle of 140° with water. The addition of Hexamethyldisilazane (HMDS) into the formulation enhanced the hydrophobicity of the coatings by extending the formation of more micro-nano scale structure. Moreover, developed coatings have 5B adhesion, significant humidity resistance, passed the 3H pencil hardness test and are thermally stable up to 250 °C. The developed process is also suitable for low temperature organic substrates, feasible for scale-up production and the stable formulation can be available in a two-pack system.