Fourier transform infrared spectroscopy and oxygen luminescence probing combined study of modified sol-gel derived film

A series of sol-gel-derived silica films are prepared by co-condensation of vinyltrimethoxysilane (VTMOS) and tetraethoxylsilane (TEOS) with various feeding molar ratios of VTMOS to TEOS under the acid-catalyzing conditions. Significant improvements of the performance of film formation are observed in these vinyl modified films. The resultant silica films are characterized by Fourier transform infrared (FT-IR) spectroscopy giving some important structural features. The main Si-O-Si vibrations shift to low wavenumber with increasing VTMOS ratios indicating more open network structures in these vinyl-containing films. The vibration bands of Si-OH (3100-3700 cm(-1)), and especially H2O (1640 cm(-1)), in the silica films are weakened with increasing VTMOS contents, revealing that the introduction of vinyl group into sol-gel systems can increase the degree of condensation and hydrophobicity of porous surface. Luminescence probing of resultant sol-gel films with Ru(bpy)(2+) complex as probe show more rapid and sensitive response to oxygen against standard TEOS-based silica film. The improvement of oxygen-sensing property can correspond to the structural characteristics obtained from IR spectroscopy. (C) 2001 Elsevier Science B.V. All rights reserved.