Spectroscopic study of preceramic polymers (xerogels) obtained by hydrolytic condensation of ethoxycyclosiloxanes

Abstract

Sol–gel method, which is based on hydrolytic polycondensation reaction, leads to formation of xerogels from simple molecules, e.g., most widely used tetraethoxysilane (TEOS). In the presented work alkoxy derivatives of cyclosiloxane molecules of general formula: Si n O n (CH 3) n (OEt) n where n = 4, 5 and 6 were applied as the molecular precursors. Polycondensation reactions were performed in the presence of tetrabutylammonium fluoride (TBAF) or HCl/NH 4OH as catalysts, without using any template or surfactant whatsoever. The composition and structure of obtained xerogels were studied by FT-IR and XRD as a main method, the MAS NMR and SEM measurements were also performed. The surface of the studied samples was measured by nitrogen adsorption methods. We have found that the obtained materials were mesoporous.