(710c) Polyelectrolyte Interactions At a Conducting Interface: A Simulation Study

Van Tassel, P. - Presenter, Yale University

Recent experiments demonstrate polyelectrolyte adsorption to a conducting surface to become continuous, i.e. to scale linearly with time over hours, upon application of a modest electric potential. Continuous polyelectrolyte adsorption offers the possibility of polymer films of tailored nanoscale thickness realized in a single step, but raises fundamental mechanistic questions. A key feature of one hypothesized mechanism involves a net attraction among like-charged polymers at the electrified interface, caused by a highly correlated counter-ion distribution and/or the presence of image charges. In this talk, we present a Monte Carlo simulation study of polyelectrolyte-polyelectrolyte interactions, with a goal of developing mechanistic insight into like-charge attraction at the electrified interface, and hence also into the continuous adsorption process. Our system consists of two parallel polymer chains, composed of charged tangent spheres, above a conducting surface, in the presence of spherical counter-ions and salt ions. We observe conditions where counter-ions preferentially locate between the polymers, and act to promote a net polymer-polymer attraction. We discuss the sensitivity of the attractive regime to a Coulombic coupling parameter, to counter-ion size, and to the nature of the underlying substrate. We also compare simulation results to those of a strong Coulomb coupling statistical mechanical model, and to our ongoing experiments.