Effect of component ratios on the performance of UV curing organic/inorganic coating

A transparent, hard organic/inorganic hybrid coating system was prepared using various mixing ratios of its components; the sequential process involved UV curing of commercially organic resins followed by thermal condensation of the inorganic component at 120 degrees C for 12 h. The hybrid precursors were spin-coated on polycarbonate substrates to form 4 similar to 13 mu m thick films, with no cracks. The inorganic component was prepared through sol-gel reactions by mixing 5:1, 1:2, 2:1, and 1:5 mole ratios of tetraethoxysilane (TEOS) and methacryloxypropyltrimethoxysilane (MPTMS); the organic component was prepared by adding of 4:3:3 wt% ratio of UV-curable urethane acrylate oligomer, multifunctional thmethylolpropanetriacrylate (TMPTA), and hexanedioldiacrylate (HDDA). In general, as the inorganic SiO2 content and the mixing ratio of coupling agent MPTMS increased, higher miscibility of hybrids occurred without phase separation, which gave greatly improved abrasion resistance when compared to organic component-dominated specimens. The morphology and phase homogeneity of the coating systems on the nanometer scale were investigated by chemical and microscopic characterization.