Coloured organic-inorganic coatings on glass

Organic-inorganic hybrids were obtained by the alcoholate sol-gel method. The characteristic feature of these materials is that CnHm groups are connected to silicon atoms by C-Si bonds. Such structures are compatible matrices for organic dyes. The gels prepared from pure tetraethoxysilane (TEOS) modified with methyltrimethoxysilane (MTMS) or phenyltriethoxysilane (PhTES) were subjected to heat treatment in the temperature range 40-500 °C. Then, they were examined by FTIR spectroscopy. All gels after heating at 100 °C were analysed by 29SiMASNMR. It has been observed that polycondensation proceeds faster in presence of an organic modifier compared to pure TEOS. Moreover, it has been found that copolymers form between the units of TEOS (Q) and organic modifiers (D). Thermal stability of copolymers depends on the modifier type but the temperature of 350 °C should not be exceeded. The hybrid materials were coloured by introducing organic absorption dyes to the gel matrix. Hybrid films were deposited on glass plates by a dip-coating technique. Optical properties of those films were examined by measuring light transmission in the range of visual wavelengths (UV-vis spectroscopy).