Size control of nanostructured silica using chitosan template and fractal geometry: effect of chitosan/silica ratio and aging temperature
- 391 Downloads
The uses of low cost, renewable, environmentally friendly chitosan biopolymer as the structural template to control the size of silica particles in the range of nanometer scales are attractive for their practical industrial applications. In this paper, the nanostructured silica was synthesized using sodium silicate as the silica source and chitosan as the template under mild conditions. Effects of chitosan/silica ratio and aging temperature on the formation and the control of nanostructured silica was investigated by using thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), N2-sorption measurement, and transmission electron microscopy (TEM). It was found that the silica products were composed of the aggregates of primary silica nanoparticles and nanostructured silica units. At low aging temperature, the size of nanostructured silica was decreased when increasing the chitosan/silica ratio from 0.1 to 0.4. In contrast, the reverse trend was observed at the chitosan/silica ratio of higher than 0.4. The increase of aging temperature led to the formation of larger primary silica nanoparticles and nanostructured silica, and also promoted the formation of silica/chitosan composites. The fractal dimension calculated using modified FHH method found the linear correlation at two different regimes which might reflect the aggregates of silica products at different length scales.
KeywordsChitosan concentration Aging temperature Fractal analysis Aggregates Nanostructured silica
This work was financially supported by the Thailand Research Fund through the Royal Golden Jubilee Ph.D. Program (Grant No. PHD/0012/2548), the National Science and Technology Development Agency (NSTDA Chair Professor and NANOTEC Center of Excellence) under the Postgraduate Education, and Research Programs in Petroleum and Petrochemicals, and Advanced Materials.
- 1.Iler RK (1979) The chemistry of silica. Wiley, New YorkGoogle Scholar
- 2.Brinker CJ, Scherer GW (1990) Sol-gel science: the physics and chemistry of sol–gel processing. Academic Press, New YorkGoogle Scholar
- 15.Pfeifer P, Liu KY, Rudzinski W, Steele WA, Zgrablich G (1997) Equilibria and dynamics of gas adsorption on heterogeneous solid surfaces. Elsevier, New YorkGoogle Scholar
- 17.Domard A, Domard M (2002) In: Dumitriu S (ed) Polymeric biomaterials, 2nd edn. Marcel Dekker, New YorkGoogle Scholar