Preparation and characterization of polysaccharide - silica hybrid aerogels

Abstract

Hybrid aerogels based on polysaccharides - silica were prepared and characterized. Tetramethylorthosilicate (TMOS) was used as inorganic precursor and various polysaccharides (alginate, pectin, xanthan and guar) were used as organic precursors. TMOS was added to polysaccharide aqueous solutions, resulting in stable wet gels. There were no additional chemicals or cross-linkers in the process. Produced wet gels were dried under supercritical conditions with CO2 in order to preserve their structure. The nitrogen adsorption results were compared to pure polysaccharide aerogels, prepared in our previous research. It is shown, that the addition of silica to pectin, xanthan, alginate and guar significantly improved their structural properties, primarily seen in the drastic increase of the surface area. Guar-silica aerogels reached the highest surface area of 679 m2 g−1. The thermal properties, including thermal degradation and thermal conductivity were highly improved. Among the prepared hybrid aerogels, pectin-silica samples had the lowest thermal conductivity of 19 mWm−1 K−1.