NOVEL SILICA BIOPOLYMER NANOCOMPOSITES - THE SILICA SOL-GEL PROCESS IN BIOPOLYMER ORGANOGELS

A novel sol-gel nanocomposite material is introduced which was produced by silica sol-gel processes in microemulsion organogels. Microemulsion organogels are formed by a percolating droplet network containing a biopolymer (e.g. gelatin, chitosan, etc.). Microemulsion organogels have water localized in the droplet network which permits the spatial confinement of hydrolysis and polycondensation to microheterogeneous reaction sites. In the case of microemulsion organogels, the oxid gel forms an interpenetrating network with the gelatin maze. While the formation of the microemulsion and the microemulsion organogel is controlled by interfacial processes, the aggregation process of the inorganic oxide particles is objected to gravitational forces. Therefore, we propose this system for sol-gel studies under low or microgravitational conditions. The structural features of the obtained silica-gelatin nanocomposites will be described and compared with silica-biopolymer composites of non-gelling biopolymers in microemulsions (e.g., chitosan). Comparison is made with the silica gels that form in the parent microemulsions.