SYNTHESIS AND CHARACTERIZATION OF MONOLITHIC PVA-DOPED SILICA GEL VIA FREEZE DRYING

Monolithic PVA-doped silica gels were prepared by the sol-gel process and dehydrated by conventional freeze-drying. Tetraethoxysilane (TEOS), tert-butanol (TBA) and distilled-deionized (DDI) water were used as major materials in hydrolysis of the silica gels under acid-catalyzed conditions. Characteristics of PVA-doped silica gels were evaluated by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and nitrogen adsorption-desorption analysis (BET) methods, respectively. The FT-IR patterns show that a typical feature of Si-O-Si linkages is formed. Morphological analysis by SEM indicates that a typical porous gel structure is achieved through freeze drying, and the PVA-doped silica gel has an interconnected porous structure with a pore size of 1-10 μm at macropore scale. Characterization by BET shows that the PVA-doped silica gels are mesoporous materials with a specific surface area of 1167 m²/g, a pore specific volume of 1.548 cm³/g, and an average pore size of 2.653 nm.