Dynamic light scattering studies in silica/ethylene glycol charged colloidal system

Abstract

Multiple scattering of light in colloidal suspensions can be suppressed by suspending the particles in a liquid with matching refractive index. We minimize the multiple scattering of light in charged silica suspensions by dispersing them in a mixed solvent of ethylene glycol/water (EGW). We report here the static and dynamic light scattering investigations carried out on these closely refractive index matched and deionised suspensions over a wide range of volume fractions (Ø = 0.0006-0.12). The suspensions are found to have a liquid-like order up to a volume fraction Ø of 0.02 and a crystalline order beyond this Ø value. A liquid-like ordered suspension with Ø = 0.04, when subjected to sudden compression by centrifugation, the suspension was found to freeze into a colloidal glassy state. The dynamics in liquid-like, crystalline and glassy states of these silica dispersions are analyzed and the results are compared with those reported for aqueous latex suspensions.