Structure and Dynamics of Clay Particle Dispersions

Clay particles are used as additives for many different purposes be it as viscosity modifiers, as flame retardants, for low gas permeability, or for scratch resistance. The high aspect ratio of the platelets supports all those material improvements. Very often, the fundamental understanding of platelet dispersions is at the beginning. Thus, new concepts are highly desired when it comes to the next generation of products with even higher performance.Scattering experiments provide the structural and dynamic information that is needed to understand the mechanism of clay particle dispersions. Clay particles dispersed in water and microemulsions show examples of quite low and extremely high viscosities for certain aspect ratios (Fig. 1, left)[1]. These findings are rationalized by applying a simple viscosity model of membranes in a viscous medium. The principal understanding of low viscosities was transferred to crude oil dispersions where lower viscosities were obtained at low temperatures[1]. The structure of clay/polymer dispersions was analyzed using medium and wide-angle scattering (Fig. 1, right)[2]. A simple model rationalized the findings, especially the rather low limit of platelets forming a stack at about 3-4