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Molecular Modeling of Structure and Dynamics of Nafion Protonation States.
J Phys Chem B. 2019 08 08; 123(31):6882-6891.JP

Abstract

We present the results of the atomistic molecular dynamics modeling of different protonation states of Nafion at varying hydration levels. Previous experiments have shown that the degree of deprotonation (DDP) of the sulfonic acid groups in a Nafion membrane varies significantly upon hydration. Our goal is to provide insights into the effects of variable protonation states and water content on the internal structure and vehicular transport inside the Nafion membrane. The Nafion side chain lengths showed a weak increasing trend with increasing DDP at all hydration levels, exposing more of the sulfonic acid groups to the hydrophilic/water phase. The water-phase characteristic size/diameter decreased with increasing DDP, but, interestingly, the average number of water molecules per cluster increased. The probability of water-hydronium hydrogen bond formation decreased with increasing DDP, despite an increase in the total number of such hydrogen bonds. The water diffusion was largely unaffected by the state of deprotonation. In contrast to that, the hydronium ion diffusion slowed down with increasing DDP in the overall membrane. The hydronium ion residence times around the sulfonic acid group increased with increasing DDP. Our simulations show a strong connection between the morphology of the water domains and protonation states of Nafion. Such a connection can also be expected in polyelectrolyte membranes similar to Nafion.

Authors

No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

31306017

Citation

Sengupta, Soumyadipta, and Alexey V. Lyulin. "Molecular Modeling of Structure and Dynamics of Nafion Protonation States." The Journal of Physical Chemistry. B, vol. 123, no. 31, 2019, pp. 6882-6891.
Sengupta S, Lyulin AV. Molecular Modeling of Structure and Dynamics of Nafion Protonation States. J Phys Chem B. 2019;123(31):6882-6891.
Sengupta, S., & Lyulin, A. V. (2019). Molecular Modeling of Structure and Dynamics of Nafion Protonation States. The Journal of Physical Chemistry. B, 123(31), 6882-6891. https://doi.org/10.1021/acs.jpcb.9b04534
Sengupta S, Lyulin AV. Molecular Modeling of Structure and Dynamics of Nafion Protonation States. J Phys Chem B. 2019 08 8;123(31):6882-6891. PubMed PMID: 31306017.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Molecular Modeling of Structure and Dynamics of Nafion Protonation States. AU - Sengupta,Soumyadipta, AU - Lyulin,Alexey V, Y1 - 2019/07/26/ PY - 2019/7/16/pubmed PY - 2019/7/16/medline PY - 2019/7/16/entrez SP - 6882 EP - 6891 JF - The journal of physical chemistry. B JO - J Phys Chem B VL - 123 IS - 31 N2 - We present the results of the atomistic molecular dynamics modeling of different protonation states of Nafion at varying hydration levels. Previous experiments have shown that the degree of deprotonation (DDP) of the sulfonic acid groups in a Nafion membrane varies significantly upon hydration. Our goal is to provide insights into the effects of variable protonation states and water content on the internal structure and vehicular transport inside the Nafion membrane. The Nafion side chain lengths showed a weak increasing trend with increasing DDP at all hydration levels, exposing more of the sulfonic acid groups to the hydrophilic/water phase. The water-phase characteristic size/diameter decreased with increasing DDP, but, interestingly, the average number of water molecules per cluster increased. The probability of water-hydronium hydrogen bond formation decreased with increasing DDP, despite an increase in the total number of such hydrogen bonds. The water diffusion was largely unaffected by the state of deprotonation. In contrast to that, the hydronium ion diffusion slowed down with increasing DDP in the overall membrane. The hydronium ion residence times around the sulfonic acid group increased with increasing DDP. Our simulations show a strong connection between the morphology of the water domains and protonation states of Nafion. Such a connection can also be expected in polyelectrolyte membranes similar to Nafion. SN - 1520-5207 UR - https://www.unboundmedicine.com/medline/citation/31306017/Molecular_Modeling_of_Structure_and_Dynamics_of_Nafion_Protonation_States L2 - https://dx.doi.org/10.1021/acs.jpcb.9b04534 DB - PRIME DP - Unbound Medicine ER -
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