(214ak) Polyelectrolyte Interactions: Theory and Simulation | AIChE

(214ak) Polyelectrolyte Interactions: Theory and Simulation


Van Tassel, P. - Presenter, Yale University
Sammalkorpi, M., Aalto University
Antila, H., Aalto University

Polyelectrolyte interactions govern many natural and technological processes. Recent experiments and simulations suggest like charged polymers to attract one another under certain conditions, owing to preferential counter-ion positioning between the two chains. Such attraction may have significant implications to nucleic acid delivery and polyelectrolyte film formation. We address here the problem of like-charged polymer attraction using a coarse grained model, consisting of two similarly charged aligned cylinders, oppositely charged spherical counter-ions, and spherical salt species. Employing Monte Carlo simulation, we show polymer-polymer attraction to correlate strongly with a Coulomb coupling parameter, defined as the ratio of the electrostatic interaction energy of two counter-ions at the cylinder surface to the thermal energy. We also find a significant influence of ion diameter in the regime where crowding induces ion positioning away from the cylinder surface. Two simple statistical mechanical models are proposed: a purely mean field model for larger counter-ion diameter, and a hybrid model for smaller counter-ion diameter where ions “condensed” to the cylinder surface are treated as a highly correlated 2-D one-component plasma, and ions away from the surface are treated in a mean field description. We discuss these results in light of recent experimental findings of significantly enhanced polyelectrolyte adsorption to electrified interfaces.