Adsorptive properties of sol-gel derived hybrid organic/inorganic coatings

Hybrid organic-inorganic solegel derived coatings have been prepared by dip coating on glass substrates from alcoholic solutions of tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), 3- aminopropyltriethoxysilane (APTES), 3-glycidoxypropyltrimethoxysilane (GPTMS) and phenyltriethoxysilane (PhTES). The hybrid materials have been fully characterized by means of solid state NMR spectroscopy and X-ray diffraction. The degree of cross-linking and the extent of interaction between silica and silsesquioxane phases appear dependent on the ratio between TEOS and organotrialkoxysilane and on the chemical features of the organic function linked to silicon, and influence the sorption ability towards aromatic compounds of hybrid films. The hybrid coatings have been put into an optical-grade quartz chamber placed into a UVeVISeNIR spectrophotometer and the organic compounds have been allowed flowing through the chamber recording of molecule absorption spectra vs. time. Absorbance curves vs. time have also been collected at a fixed wavelength for different molecule-coating couples and simple kinetic models have been used for comparing the adsorption capability of the different films, which has been related to the chemical interactions between molecules and coatings.