Adsorption Behavior of Polydisperse Polymeric Systems

Abstract

Adsorption behavior of polydisperse polymers at interfaces is studied by the Monte Carlo simulation method based on a lattice model. Effects of temperature and adsorption energies on the polymer density profile, cluster distributions and adsorption layer thickness are evaluated in two different polydisperse systems. It is found that adsorption properties are greatly different in these two systems. In normal distribution polydisperse systems, polymers are more sensitive to the excluded volume effects while in average distribution polymers are more inclined to adsorb on adsorbing interfaces. As higher temperature and lower attraction constrain the polymer adsorption, more clusters are found under these conditions. When temperature approaches the critical temperature of monodisperse systems, stable and large clusters exist in these two polydisperse systems. These results suggest that micro phase transition may exist in polydisperse systems. Polydisperse systems take little change of phase transition temperatures but altered the clusters morphology to some extent. The adsorption layer thickness changes are more sensitive to both temperature and polymer–interface interactions in average distribution systems when the whole polymer concentration increases slightly. This work also suggests significant differences between the polydisperse and the monodisperse systems in adsorption behavior. Therefore, quantitative system errors may exist when the monodisperse system models are used in simulation to evaluate polymer adsorption properties.