Preparation and characterization of hybrid nanocomposite coatings by photopolymerization and sol-gel process

Organic-inorganic nanocomposite hybrid coatings were prepared through a dual-cure process involving cationic photopolymerization of epoxy groups and subsequent condensation of alkoxysilane groups. The kinetics of the photopolymerization and condensation reactions were investigated; suitable conditions for obtaining a complete conversion of both reactive groups were found. The obtained films are transparent to visible light. The T_g values of the hybrids increase by increasing the TEOS content in the photocurable formulation. Also, a significant increase in surface hardness could be obtained for the hybrid systems. AFM analysis gave evidence of a strong interaction between the organic and inorganic phase with the formation of silica domains in the nanoscale range.