Biosourced polysaccharide nanocrystals to template hybrid materials

Cycle de conférences
Université Euromed de Fès M. Emanuel BELAMIE

Chitin crystalline nanorods are found in many natural nanocomposites associated with an inorganic phase like CaCO3 in crustaceans and silica in the skeleton of glass sponges. Such organicinorganic association at the nanoscale in physiological conditions served as an inspiration for new materials synthesis routes compliant with green chemistry principles. In addition, polysaccharide nanocrystals are renewable organic precursors readily prepared from industrial waste biomass. A new family of hybrid organic-inorganic nano-composites has been synthesized based on a versatile colloidbased approach, which allows for a high level of control over materials texture and morphology. Hybrid materials can be obtained by sol-gel processing into microparticles by spray-drying, fibers by electrospinning and thin films by spin-coating. The characteristics of the silica-chitin nano-composites can be transferred to their mesoporous counterpart by simple calcination [1,2]. The porous materials have pore diameters in the 5-20 nm range and specific surface areas up to 500 m2 .g-1 . For heterogeneous catalysis applications (selective oxidation), titanium alkoxides have been introduced to form mixed oxides SiO2-TiO2. The dispersion of Ti sites can be tuned through synthesis conditions [3].