Chemically modified silicon dioxide surfaces. Wetting properties of compact n-alkyl-dimethylsiloxy layers, and their mixed surface crystals. The Question of Wetting of Molecularly Rough and of Swollen Surfaces†

摘要: By means of contact angle measurements, it has been shown that compact alkyl-dimethyl-siloxy layers can be obtained on the surface acid leached glass using method previously developed for fume silica. Subsequently, a series densest possible alkyl-dimethylsiloxy were prepared having non-branched alkyl substituents, CzH2z+1, (with z=1, 2, 3, 6, 10, 14, 18 and 22) wetting angles measured as function temperature. On surfaces coated with longer substituents formation mixed crystals, consisting sparse chemically bonded layer n-alkane acting agent, observed at low temperatures. At higher temperatures such appeared to «molten», same time swollen by agent. Equations have derived deduce free energies account properties rough surfaces. Application results data presented in this paper revealed covered short chains (methyl, ethyl propyl) are those long (tetradecyl, octadecyl docosyl) swollen. Surfaces formed hexyl- decyl-dimethylsiloxy exhibit intermediate properties.