Hybrid organic-inorganic gels containing perfluoro-alkyl moieties

Perfluoroalkyltrialkoxysilanes were prepared by hydrosilylation of the ally lic or vinylic derivatives with trialkoxysilane or with trichlorosilane (fo llowed by a quantitative methanolysis). The hydrolysis and polycondensation of these precursors were performed in the presence of tetrabutylammoniumfl uoride (TBAF) as the catalyst, leading to a series of new polysilsesquioxan es, which were characterized by solid state C-13 and Si-29 CPMAS NMR. The p orosity and surface area of these materials were determined by N-2 absorpti on experiments. Thermogravimetric analyses (TGA) were also performed. The s urface properties of films prepared from these silsesquioxanes were studied by contact angle measurements. The hybrids having fluoroalkyl groups at th e surface of the material showed a better thermostability and a higher hydr ophobic and oleophobic character than their hydrocarbon analogues. (C) 2000 Elsevier Science S.A. All rights reserved.