Aggregate dynamics in ionomer melts*

Melts of ion-containing polymers are desirable as battery materials for their stability. However, the low dielectric constants of polymer backbones drive ion aggregation, which can limit mobility and thus conductivity. Understanding how ion transport is connected to morphology and polymer architecture is critical for designing candidate ionomers. We simulate coarse-grained ionomer melts with explicit counterions, where evenly-spaced charged groups are pendant to the polymer backbones. Previously, we observed that pendant architectures can drive the formation of isolated ionic aggregates (clusters). Here, we use new cluster identification algorithms to show that ion transport in pendant systems is slaved to the collective dynamics of aggregates, where clusters collide, merge, and then separate while exchanging ions. Hopping of isolated ions between clusters does not occur. We extract important aggregate timescales and correlate them with ion mean-squared displacements.