Multilayered adsorption of macrocations and macroanions on colloidal spheres as studied by dynamic light scattering measurements

Abstract

The electrophoretic light scattering data on the thickness of the alternate multiple adsorption layers of macrocations and macroanions on the surfaces of colloidal spheres, which have been published by the authors in Colloid and Polymer Science (1999) 277;813, (2000) 278:380 and (2002) 280:533, are reexamined with help of the dynamic light scattering measurements. Colloidal silica spheres (110 nm in diameter) and monodispersed polystyrene spheres (220 nm) are used as colloidal spheres. The macrocations used are poly(4-vinyl-N-n-butylpyridinium bromide and poly(allylamine). Sodium poly(styrene sulfonate) and sodium polyacrylate are used as macroanions. It was clarified in the previous work that a very small amount of the large aggregates of the macroions coexists for most of the suspensions and the thickness values reported are large compared with the true values. The corrected thickness values support the continuous thin layer's growing adsorption of the macroions on the colloidal surfaces but do not support the expansion–contraction-type adsorption.