Hydrorepellent properties of organic–inorganic hybrid materials

Novel hybrid organic–inorganic materials to be used as hydrophobic coatings for ancient and modern lithic materials have been prepared. The reaction between (3-glycidyloxypropyl)trimethoxysilane (GLYTS) and 3-aminopropyl-methyldiethoxysilane (AMTS) in 2:1 and 5:1 stoichiometric ratios, followed by means of 13C NMR j mod experiments in solution, leads to transparent and crack-free solids. The products such obtained have been characterized by means of μ-Raman, FT-IR and TG-DTA investigations. Their hydrophobic behavior has been studied by contact angle measurements by Wilhelmy method on glass slides properly coated by dip coating. Contact angle investigations have been also carried out on the above blends added of the fluorine-containing comonomers 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluorononyl ether (GLY16F) and 3,3,3-trifluoropropyl-trimethoxysilane (TFP-TMS). The effectiveness of the cited materials as conservation products for lithic substrates has been tested by mercury intrusion porosimetry and water capillarity absorption by wicking method.