Aging of aqueous laponite dispersions in the presence of sodium polystyrene sulfonate

Abstract

Aqueous suspensions of Laponite with discotic particles are well-studied and find a wide range of applications in industry. A new direction of their implementation is polymer composites that can exhibit improved physical properties. We have studied the aging of aqueous suspensions of Laponite and sodium polystyrene sulfonate (PSS-Na) and both their microscopic (small-angle X-ray scattering, SAXS) and macroscopic (small amplitude oscillatory shear (SAOS) rheometry) properties. The concentration of Laponite, CL, was fixed at 2.5% wt and concentration of PSS-Na, Cp, was varied within 0-0.5% wt (0-24.2 mM). It is shown that the adding of PSS-Na significantly accelerates the aging. Nevertheless, the systems were stable against the sedimentation, and the flocculation didn't occur. Polyelectrolyte induced the appearance of large-scale fractal heterogeneities, which became more compact in the course of the aging. © V. SAVENKO, L. BULAVIN, M. RAWISO, N. LEBOVKA, 2014.