Ion transporting polymers constitute vital components in clean energy generation and storage devices including electrolytic media in fuel cells and ion conducting separators in batteries. While different polymers are currently in use, achieving controlled ion transport and storage ability while retaining mechanical and chemical stability remains a challenge since under the conditions which transport and storage are optimized, either mechanical or chemical stabilities are compromised. Designing block-co-polymers with ion transporting blocks tethered to blocks that enhance mechanical and chemical stability is one promising way to mitigate the challenge. These fascinating ionic co-polymers however assemble into structures that are far from equilibrium particularly because the inherent tendency of the ionic groups to cluster. Large scale molecular dynamics simulations provide an exquisite tool to obtain molecular insight into polymeric complex systems. Here we present the first molecular-level computational insight of the behavior of a pentablock, <i>A-B-C-B-A,</i> co-polymer that consists of an A block of poly(t-butyl-styrene), a B block of ethylene-r-propylene and a C block of a randomly sulfonated polystyrene. There structure in presence of solvents is a delicate balance of van der Waals interactions with electrostatic ones that often drive the formation of hierarchal structures. Here we will discuss the unique structure and dynamics of isolated molecules in hydrophilic and hydrophobic solutions, followed by their assembly into micelles, shown the the atathced image, with a unique nano-porous core. Finally, the structure and dynamics of the polymer in a melt will be discussed.

From single molecules to menras: molecular dynamic simulation insight into ionizable co-molymers

2019 Spring National Meeting

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