Small-angle neutron-scattering studies of silica sols in water at high temperatures

Abstract

The temperature dependence of the interparticle interactions in a silica sol have been investigated in the range 298–533 K by small-angle neutron scattering. By applying the rescaled mean spherical approximation (MSA), due to Hansen and Hayter, closed analytic solutions of the structure factor, S(Q), for a screened coulombic potential have been fitted to experimental scattering data to obtain the effective surface charge and potential of the silica particles. As the temperature is increased, marked reductions in the interaction potential are observed, which are partially restored on cooling. These effects are ascribed to the considerable changes in the dielectric properties and ionic dissociation of water that occur at these elevated temperatures.