Hybrid organic–inorganic gels containing perfluoro-alkyl moieties

Perfluoroalkyltrialkoxysilanes were prepared by hydrosilylation of the allylic or vinylic derivatives with trialkoxysilane or with trichlorosilane (followed by a quantitative methanolysis). The hydrolysis and polycondensation of these precursors were performed in the presence of tetrabutylammoniumfluoride (TBAF) as the catalyst, leading to a series of new polysilsesquioxanes, which were characterized by solid state 13C and 29Si CPMAS NMR. The porosity and surface area of these materials were determined by N2 absorption experiments. Thermogravimetric analyses (TGA) were also performed. The surface properties of films prepared from these silsesquioxanes were studied by contact angle measurements. The hybrids having fluoroalkyl groups at the surface of the material showed a better thermostability and a higher hydrophobic and oleophobic character than their hydrocarbon analogues.