Porous silica derived from chitosan-containing hybrid composites

In this paper, we report the preparation by the sol-gel technique of organic-inorganic hybrid composites containing the biopolymer chitosan incorporated in a siloxane-based inorganic network. The hybrid xerogels were transformed into porous silica particles by elimination of the organic phase. Surface characteristics of the silica samples can be easily tailored. In this way Brunauer-Emmett-Teller areas, pore volume, and pore diameter of the prepared silica can be predetermined within a wide range. Morphology of the particles at longer length scales can be designed to obtain either irregularly shaped particles with layered morphology or spherical particles. The results are explained on the basis of the cationic polyelectrolytic properties of chitosan, which allows easy association with siloxane oligomers, the precursors of silica in forming hybrid nanocomposites.