Synchronous alternate multilayered adsorption of poly(4-vinyl-N-n-butylpyridinium) cations and poly(styrene sulfonate) anions on polystyrene colloidal spheres

Alternate multiple adsorbed layers of up to six macrocations [poly(4-vinyl- N-n-butylpyridinium bromide)] and macroanions [sodium poly(styrene sulfonat e)] are formed on monodispersed polystyrene colloidal spheres above the cri tical concentration of the macroions, m*. The m* value is the minimum numbe r of macroions needed to reverse the sign of the zeta potential of the sphe res in the first adsorption step. Alternate sign reversal in the zeta poten tial and expansive-contractive thickness changes are observed on the repeat ed and alternate addition of macrocations first and macroanions next. When the macroanions are added first, sign reversal in the zeta potential and re versible expansion and contraction do not occur. Breaking of the alternate multiple-type adsorption also occurs when equivalency in the number of diss ociative groups of macrocations and macroanions is broken. Synchronous conf ormational changes of macrocations and macroanions in the multiple-adsorbed layers occurs only when the conformational rigidities with the multiple el ectrostatic and hydrophobic attraction and/or repulsion between macrocation s and macroanions are delicately balanced.