A New Effective Potential for Colloidal Dispersions with Polymer Chains Emerging from Mesoscopic Scale Interactions

A new potential of mean force is proposed for colloidal dispersions, which is obtained from coarse - grained, pair interactions between colloidal particles formed by the explicit grouping of particles that are themselves groups of atoms and molecules. Using numerical simulations, we start by constructing colloidal particles made up of 250 mesoscopic particles joined by springs and interacting with each other through short - range forces. Afterward we proceed to model several colloidal concentrations and obtain the colloidal particles pair correlation function, from which we derive the potential of mean force. In our second case study, we add linear polymer chains of the same length that attach by one of their ends to the colloids, at a fixed colloidal concentration, and carry out numerical simulations at increasing concentrations of polymer chains, from which we obtain the potential of mean force once again following the same procedure as in the previous case. For the last case study we fixed both the colloids' and the polymer chains' concentration, while increasing the length of the polymer chains and obtain again the potential of mean force. In all of these simulations, the solvent particles are included explicitly. Using these data we propose a new effective potential of interaction for colloidal dispersion whose parameters can be obtained from mesoscopic scale parameters and carry out standard molecular dynamics simulations with this new potential, thereby providing a route for more fundamentally obtained, coarse - grained approaches to model colloidal dispersions.