A SANS study of organoclay dispersions

Small-angle neutron scattering (SANS) is used to investigate the dispersion in toluene of various forms of the complex, Cloisite C15A. Cloisite is a commercially important exchanged clay prepared from montmorillonite and the cation di-tallow ammonium. Points discussed include estimates of the extent to which the complex is dispersed, the amount of organic clay platelet surface layer coverage, and possible network formation of the complex in the solvent. From power-law plots of the scattered neutron intensity versus the wave vector, it is estimated that C15A is well dispersed into clusters which consist of a stack of between three and seven di-tallow-coated montmorillonite platelets. The removal of excess di-tallow from the surface layer reduces the number of platelets in the cluster. Substitution of dimethydioctodecyl ammonium for the ditallow molecule promotes network formation. It is demonstrated that SANS is a powerful tool for examining these complicated organic/inorganic systems.