Influence of particle size on the stability of polystyrene latices with an adsorbed layer of nonionic surface active agent

Abstract

The coagulation of monodisperse polystyrene latices by nitric by nitric acid has been studied at different concentrations of a nonionic surface active agent, n-dodecylhexaoxyethylene glycol monoether C₁₂H₂₅[OCH₂CH₂]₆OH; a range of particle sizes from 60 to 870 nm was examined. With an adsorbed monolayer of the nonionic surface active agent the small particle size latices are stable in the absence of an electrostatic charge but the larger particles cannot be stabilized under these conditions. The experimental results are consistent with a theory based on the concept that the adsorbed layer acts as a steric barrier and also modifies the van der Waals interactions.