Electrostatic adsorption of polystyrene particles with different surface charges onto the surface of an ultrathin polymer film

The adsorption of polystyrene particles with different surface charges from aqueous dispersions onto the surfaces of cationic ultrathin polymer films was quantified using a quartz crystal microbalance (QCM) technique. The polymer films were prepared by the alternate adsorption technique from poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) in the presence or absence of NaCl onto the QCM substrate. Particle adsorption, as a result of electrostatic interaction, onto the outermost PAH surface was observed by QCM. The adsorption behavior of two differently charged particles was examined and revealed greater adsorption of particles with a relatively larger surface charge. The dependence of adsorption of all the particles against an outermost PAH thickness in a polymer precursor film was described by a sigmoid curve, indicating that a critical charge on/in the film is required for adsorption. SEM observations showed monolayer adsorption without three-dimensional aggregation.