Structural and thermal characterization of hybrid materials based on TEOS and DCN

Abstract

Solution and solid-state Silicon-29 NMR spectroscopy, X-ray diffraction (WAXS), infrared spectroscopy (IR), thermogravimetric analysis (TGA), and differential scanning calorimetric were used for the characterization of organic–inorganic hybrids, obtained from 4-[[5-dichloromethylsilyl]pentyl]oxy]-cyanobenzene (DCN) and tetraethoxysilane (TEOS). Presence of reaction intermediates during chemical reactions was characterized by NMR. The hybrids are mainly composed of a siloxane copolymer with silicate units. Copolymer has pendant groups of pentyl-oxy-cyanobenzene that behave as chromophores. The nature of ordered–disordered phases was analyzed by X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. Ordered phase has a mesogenic structure containing the siloxane copolymer. The disordered phase is mainly silica glass. Molecular modeling for an idealized section of the copolymer suggests that pentyl-oxy-cyanobenzene side-chains align as rigid mesogens along the polymer backbone. Hybrids present self diffraction patterns in coherent luminous rings forms. These patterns indicate the presence of nonlinear optic (NLO) properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009