Molecular modelling of structure and dynamics of nafion protonation states

Soumyadipta Sengupta (Corresponding author), Alexey V. Lyulin

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

Uittreksel

We present the results of the atomistic molecular-dynamics modelling 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 the degree of deprotonation (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.

TaalEngels
Pagina's6882-6891
TijdschriftJournal of Physical Chemistry B
Volume123
Nummer van het tijdschrift31
DOI's
StatusGepubliceerd - 15 jul 2019

Vingerafdruk

Deprotonation
Molecular modeling
Protonation
Hydration
Membranes
Water
Acids
Hydrogen bonds
Ions
Polyelectrolytes
Chain length
Water content
Molecular dynamics
Molecules

Citeer dit

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title = "Molecular modelling of structure and dynamics of nafion protonation states",
abstract = "We present the results of the atomistic molecular-dynamics modelling 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 the degree of deprotonation (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.",
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Molecular modelling of structure and dynamics of nafion protonation states. / Sengupta, Soumyadipta (Corresponding author); Lyulin, Alexey V.

In: Journal of Physical Chemistry B, Vol. 123, Nr. 31, 15.07.2019, blz. 6882-6891.

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

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