Substantial films of polymerized γ-glycidoxytrimethyl silane were prepared and found to be mechanically very weak. It is suggested, by analogy with natural rubber, that their structure is a spiral with pendant hydroxyl groups along the core which are thus inaccessible. Reflectance spectroscopy of much thinner films of this silane indicated a loss of freedom of the hydroxyl groups as the thickness diminished. It is suggested that this is due to destruction of the spiral structure with consequent availability of the hydroxyl groups for hydrogen bonding to the oxide surface of the substrate.