Simultaneous adsorption of poly(vinylpyrrolidone) and anionic hydrocarbon/fluorocarbon surfactant from their binary mixtures on polystyrene latex

Lithium dodecyl sulfate (LiDS)/lithium perfluorooctanesulfonate (LiFOS) and poly(vinylpyrrolidone) (PVP) were simultaneously adsorbed to polystyrene latex particles (PS) with diameter of 261 nm from PVP-LiDS and PVP-LiFOS binary mixed aqueous solutions. The conformation of PVP adsorbed on PS was estimated by using ESR. The thickness of the adsorbed layer was also determined by photon correlation spectroscopy (PCS) after pre-fractionation by sedimentation field-flow fractionation (sedFFF) which removed the aggregates and permitted an accurate PCS-based determination of the thickness of the coating layer. The adsorption of PVP was enhanced in the presence of LIDS at low LiDS concentrations owing to the formation of a surface complex of PVP and LIDS, followed by a decrease at high LIDS concentrations. A similar trend was observed in the PVP-LiFOS system. In both the PVP-LiDS and PVP-LiFOS systems, the conformation of PVP adsorbed was changed remarkably from loops and tails to trains with the surfactant concentration. The fraction of train segments in the PVP-LIFOS system was greater than that in the PVP-LiDS system, especially in the high surfactant concentration region. The thickness of PVP adsorbed on PS from the binary mixed solutions estimated from PCS decreased with an increase of the surfactant concentration. Thus, the ESR results were well correlated with the thickness of PVP adsorbed obtained from PCS.