Charge delocalization effects on Nafion structure and water /proton dynamics in hydrated environments

Rakesh Pant, Soumyadipta Sengupta, Alexey V. Lyulin (Corresponding author), Arun Venkatnathan (Corresponding author)

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Abstract

In this work, using molecular dynamics simulations, we examine the effect of atomic charge delocalization on the pendant side chain of Nafion membrane on the structural and dynamical properties in various hydrated environments. The sulfur-sulfur radial distribution functions suggest that the sulfonate groups of the pendant side chain have closer geometric proximity with an increase in charge delocalization. However, the interactions of the sulfonate groups with water molecules/hydronium ions show a slight change with the charge delocalization. The average water cluster size decreases significantly with charge delocalization, though the diffusion coefficients of water molecules (at medium and higher water concentration) increase initially and then decreases slightly with excessive charge delocalization. The diffusion coefficients of hydronium ions do not follow any particular trend with charge delocalization. A complex interplay between sulfur-sulfur, sulfur-water/hydronium interactions, and water cluster distribution plays an essential role in the magnitude of the diffusion coefficient of water molecules and hydronium ions.

Original languageEnglish
Article number112340
Number of pages6
JournalFluid Phase Equilibria
Volume504
DOIs
Publication statusPublished - 15 Jan 2020

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Keywords

  • Charge delocalization
  • Cluster distribution
  • Diffusion coefficient
  • Molecular dynamics
  • Nafion

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