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Boran Ma1 Trung Dac Nguyen1 Victor Pryamitsyn1 Monica Olvera de la Cruz1

1, Northwestern University, Evanston, Illinois, United States

Understanding of the relationships between ionomer chain morphology, dynamics and counter ion mobility is a key factor in the design of ion conducting membranes for battery applications. In this study, we investigate the influence of electrostatic interaction strength (lB) between randomly charged copolymers (ionomers) and counter ions on the structural and dynamic features of a model system of random ionomer melts. Using Coarse-Grained Molecular Dynamics (CGMD) simulations, we find that variations in lB remarkably affect the formation of ionic aggregates (charged monomer – counter ion clusters), ion mobility, and polymer dynamics for a range of average charge fractions. Specifically, an increase in lB leads to larger ionic cluster sizes and reduced polymer and ion mobility. Analysis of size distribution of the clusters along with clustering morphology characterization further reveals a percolation point at which the system undergoes a transition from discrete clusters to a percolated cluster. Finally, at sufficiently high values of lB, we observe arrested heterogeneous ions mobility, which is correlated with an increase in ion cluster size. These findings provide insights into the role of electrostatics in governing the nanostructures formed in ionomers.

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