Chitosan Bio-Based Organic-Inorganic Hybrid Aerogel Microspheres

Recently, organicinorganic hybrid materials have attracted tremendous attention thanks to their outstanding properties, their efficiency, versatility and their promising applications in a broad range of areas at the interface of chemistry and biology. This article deals with a new family of surface-reactive organicinorganic hybrid materials built from chitosan microspheres. The gelation of chitosan (a renewable amino carbohydrate obtained by deacetylation of chitin) by pH inversion affords highly dispersed fibrillar networks shaped as self-standing microspheres. Nanocasting of solgel processable monomeric alkoxides inside these natural hydrocolloids and their subsequent CO2 supercritical drying provide high-surface-area organicinorganic hybrid materials. Examples including chitosanSiO2, chitosanTiO2, chitosanredox-clusters and chitosanclay-aerogel microspheres are described and discussed on the basis of their textural and structural properties, thermal and chemical stability and their performance in catalysis and adsorption.