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Abstract: Two lamellar organosilica films made up of stacks of head-to-head and head-to-tail alkyl bilayers were synthesized by a UV-driven polymerization of n-C18H37SiCl3 and n-C18H37Si(OCH3)3, respectively. In addition to thermogravimetry and small-angle X-ray scattering, the characterization of these multilayer systems was focused on a variety of multinuclear solid-state NMR methods (1H, 29Si, 13C, 2D WISE). The chemical structure of the siloxane interlayer, the alkyl chain conformation and thermal stability were systematically investigated and compared. Through its marked sensitivity to molecular motion, solid-state NMR was used to investigate the effect of interdigitation on alkyl chain dynamics. [Copyright &y& Elsevier]

The article discusses the synthesis of a novel single hybrid monomer combining a vinylether and trimethoxysilane groups in the same molecule through chemoselective hydrosilation. It was also subjected to ultraviolet (UV)-irradiation in the presence of a triarylsulfonium salt. A type II polyvinyl-polysilicate nanocomposite film resulted from the simultaneous occurrence of two acid-catalyzed processes. Parameters such as laminated conditions, UV irradiation equipment and film thickness were also investigated.

Photoacid-catalyzed sol–gel polymerization isnow recognizedas a powerful single-step synthetic approach to the synthesis of hybridfilms, which can be distinguished from conventional sol–gelmethods by higher reactivity and a solvent-free process. Despite itsutility, the mechanism is not yet understood, in particular what chemical,physical, and photochemical parameters determine the precise sequence,kinetics, and advancement of this UV inorganic photopolymerization.Here, using mainly transmission real-time Fourier transformed infrared(RT-FTIR) spectroscopy, we characterize in situthehydrolysis–condensation reactions of oligomeric silicon alkoxidesand the formation of byproducts. Systematic review and assessmentof numerous processing variables (relative humidity, film thickness,precursor structure, nature, and the concentration of photoacid generator)prove that the reaction kinetics are controlled by the two independentphenomena: the intrinsic chemical reaction rates and the water vaporpermeation into the film. [ABSTRACT FROM AUTHOR]