Light Scattering Study on Sol-Gel Transformation of SiO2 Colloid at Extremely High Concentrations

Xu Yingnian and Yoshikata Koga
Department of Chemistry, The University of British Columbia, Vancouver, B.C. V6T 1Z1, Canada

Abstract: Ludox SiO2 sols with a reasonably uniform size of 12 nm and in the high concentration of 10 to 40 wt% were transformed to gels by lowering the pH. The process from sol to gel, followed by light scattering, did not show a sign of fractal growth within the length scale of observation (>40 nm). Rather, a density fluctuation due to a dynamic (non-equilibrium) disorder was apparent. Together with the results of viscosity measurements, it was concluded that the process consists of 3 stages: 1) A dynamic (non-equilibrium) density fluctuation grows rapidly. 2) Such density fluctuation acquires some order. 3) The entire bulk loses fluidity and becomes a macroscopic gel.

Key Words: Light Scattering Study • SiO2 Colloids • Sol-gel Transformation

Clays and Clay Minerals; April 1998 v. 46; no. 2; p. 161-166; DOI: 10.1346/CCMN.1998.0460206
© 1998, The Clay Minerals Society
Clay Minerals Society (www.clays.org)