Fundamentals of aggregation in concentrated dispersions: Fiber-optic quasielastic light scattering and linear viscoelastic measurements

Abstract

Fiber-optic quasielastic light scattering and oscillatory shear rheology are employed to monitor the structure formation in concentrated, aqueous dispersions of model, electrostatically stabilized, polymer colloids. A regime of fractal scaling is observed in the vicinity of the gel point, as signified by a power law decay in the autocorrelation function with delay time and a power law dependence of the shear moduli on frequency. The power law exponents and the gel times extracted from the two techniques are compared for the first time on the same dispersion. The details of structure formation and aggregation kinetics in these concentrated dispersions are compared to the universal behavior of DLCA and RLCA aggregation observed at dilute concentrations in these and other dispersions, as well as to polymer gelation.