Chitosan-nanosilica hybrid materials: Preparation and properties

tThe research focuses on the synthesis of novel organic–inorganic hybrid materials based on polysac-charide chitosan and nanosilicas (SiO 2, TiO2/SiO2and Al2O3/SiO2). The chitosan modified nanooxideswere obtained by the equilibrium adsorption method. The chitosan adsorption capacities of silica/titaniaand silica/alumina are higher than of the plain silica due to the additional active sites present on thesurfaces of the mixed oxides. The hybrid materials were characterized by low-temperature nitrogenadsorption/desorption, photon correlation spectroscopy (PCS), scanning electron microscopy (SEM), ther-mogravimetry (TG/DTG) and temperature-programmed desorption with mass spectrometry control (TPDMS) methods. The chitosan treatment only modestly influences the surface area SBETof the nanooxidesbut the rearrangement of the secondary and tertiary structures (aggregates and agglomerates) results inan enhancement of the mesoporosity and affects the size of the aggregates. The more severe thermode-struction of the polysaccharide desorbing from the modified mixed silicas indicates a stronger interactionbetween the chitosan and the mixed oxides compared to the silanol groups of the plain silica surface