Dynamics of Model Ionomer Melts of Various Architectures

Abstract

Ion-containing polymers have potential as single-ion conducting battery electrolyte materials. Their conductivity is often too low for such applications due to the low dielectric polymer backbone and resulting strong aggregation of ions. We simulate coarse-grained ionomer melts (with explicit counterions) of various polymer architectures to understand the effect of polymer connectivity on the dynamics. We report on the polymer and counterion dynamics as a function of periodically or randomly spaced charged groups, which can be placed in the backbone or pendant to it. The spacer length is also varied. The simulations reveal the mechanism of ion transport, the coupling between counterion and polymer dynamics, and the dependence of the ion dynamics on polymer architecture. Within the ionic aggregrates, ion dynamics is rather fluid and relatively fast. The larger scale dynamics (time and length) depends strongly on the large scale morphology of the ionomer. Systems with percolated clusters have faster counter...