Counterion distribution around a polyelectrolyte confined in a metal- organic framework

LX Xie and KY Chan and VCY Li, MOLECULAR SIMULATION, 48, 926-934 (2022).

DOI: 10.1080/08927022.2022.2068797

Recently, polyelectrolytes confined in metal-organic frameworks (MOFs) are reported to demonstrate superior ion exchange with high selectivity. To reveal the counterion distribution around spatially confined polyelectrolytes without direct experimental measurements, we perform molecular dynamics simulations of ionic solution in equilibrium with a polyelectrolyte-MOF composite in explicit water. In contrast to the reported qualitative work on linear polymer conformation in vacuum, polyelectrolytes behave as stiff-like polymers after threading into the one-dimensional channels of MIL-53(Al). Consequently, the counterions tend to be uniformly distributed and locally condensed around the linearised polyelectrolyte chain. In addition to the high ion exchange performance properties of polyelectrolyte-MOF composites, the unique distribution of counterions and the structural dynamics of the confined polyelectrolyte would lead to other potential applications in membranes and interfacial technologies.

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