INTERACTION OF NONIONIC POLYMERS AT A CLAY INTERFACE

The structure and dynamics at the interface of swelling clays (smectit es) are crucial to such diverse applications as drilling for oil, cosm etics, paints, water treatment, or chemical reactions, From our previo us NMR studies on clay suspensions, we have shown how the orientation of interfacial molecules is affected by the clay structure,(1) by the nature of counterions,(2) or by the composition of the liquid phase.(3 ) These results have been mainly obtained from the analysis of residua l quadrupolar splittings of nuclei from interfacial species, In this w ork, we report our studies on a clay montmorillonite suspended in aque ous solutions of non ionic polymers, The polymer perturbs the structur e within the interfacial region as deduced from the variations of the splittings of water quadrupolar nuclei and of sodium-23 relaxation par ameters in terms of the polymer concentration, Proton self-diffusion c oefficients and carbon-13 relaxation times are measured to describe th e influence of the clay on the polymer mobility, The dependence of the polymer nature on these parameters is also investigated. Copyright (C ) 1996 Elsevier Science Inc.