Thin coating of crosslinked polymethylhydrosiloxane are grafted on silica using sol-gel process that leads to polymer layers tailored in term of thickness and elasticity. The degree of crosslinking is tuned by sol-gel polycondensation of a mixture of methyldiethoxysilane (DH) HSi(CH3)(OCH2CH3)(2) and triethoxysilane (TH) Hsi(OCH2CH3)(3), yielding triethoxysilane-based networks. Samples with well-defined thicknesses from nanometer to micrometer range are prepared by sol-gel dip-coating method on silicon surface. Homogeneous or gradient-thickness coating can be produced in this way. It results in surface-attached networks bearing Si-H functionalities covalently anchored to the substrate. Powdered gels of DH/TH composition from 50/50 to 95/5 (mol %) were also prepared for a comparison purpose. The structure of the gels was investigated by NMR and FTIR, showing that DH/TH mixtures react totally to yield homogeneous matrix. The surface-attached polymer films are very stable and present high hydrophobicity as evidenced by contact angle measurements. Their-surface and mechanical properties have been qualitatively studied using the atomic force microscopy. (c) 2007 Wiley Periodicals, Inc.