Silicate Clay Platelet Dispersion in a Polymer Matrix

Abstract

The use of dynamic light scattering to monitor the dispersion of clay platelets in a polymer matrix is described. The dispersed clay/polymer composite was prepared by joining surfactant monomers to synthetic hectorite clay platelets by a cationic exchange reaction and subsequently polymerizing with acrylamide. Dispersion of the organically modified clay in aqueous solution was facilitated by preparing a clay surfactant precursor suspension with a surfactant concentration significantly above the clay cation exchange capacity. At lower surfactant concentrations the clay does not disperse but instead forms large polydisperse aggregates unsuitable for making homogeneous composites. The presence of these aggregates could not be found in an x-ray powder diffraction scan but were clearly detected using dynamic light scattering.