Layer-by-layer self assembly of polyelectrolytes on colloidal particles

Polyelectrolytes have been consecutively adsorbed onto charged polystyrene latex particles, forming stable ultrathin multilayer films. Film growth has been followed by electrophoresis, dynamic light scattering, single particle light scattering and fluorescence intensity measurements. Desorption of bound polyelectrolytes has been followed by HPLC. A low percentage of particle aggregates were found if a centrifugation-based technique was applied, whereas a larger number of particle aggregates were observed if polyelectrolytes were consecutively added at saturating concentrations and if centrifugation was avoided. Single particle light scattering allowed for adsorption layer thickness determination. If a layer refractive index of 1.47 was assumed the thickness of a poly(allylamine hydrochloride)/poly (styrene sulfonate) layer pair formed in 0.5 M NaCl was found to be 2-3 nm. (C) 1998 Elsevier Science B.V.