Competitive adsorption of surfactants and polymers on colloids by means of mesoscopic simulations

The study of competitive and cooperative adsorption of functionalized molecules such as polymers, rheology modifiers and surfactant molecules on colloidal particles immersed in a solvent is undertaken using coarse grained, dissipative particle dynamics simulations. The results show that a complex picture emerges from the simulations, one where dispersants and surfactants adsorb cooperatively up to certain concentrations, on colloidal particles, but as the surfactant concentration increases it leads to dispersant desorption. The presence of rheology modifying agents in the colloidal dispersion adds complexity through the association of surfactant micelles to hydrophobic sites of these agents. Analysis of the simulation results reported here point clearly to the self association of the hydrophobic sites along the different polymer molecules as the mechanism responsible for their competitive and cooperative adsorption.