Interpreting effective energy barriers to membrane permeation in terms of a heterogeneous energy landscape

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Hauptverfasser: Schwindt, Nathanael S., Avidar, Mor, Epsztein, Razi, Straub, Anthony P., Shirts, Michael R.
Format: Preprint
Veröffentlicht: 2024
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author Schwindt, Nathanael S.
Avidar, Mor
Epsztein, Razi
Straub, Anthony P.
Shirts, Michael R.
author_facet Schwindt, Nathanael S.
Avidar, Mor
Epsztein, Razi
Straub, Anthony P.
Shirts, Michael R.
contents Major efforts in recent years have been directed towards understanding molecular transport in polymeric membranes, in particular reverse osmosis and nanofiltration membranes. Transition-state theory is an increasingly common approach to explore mechanisms of transmembrane permeation with molecular details, but most applications treat all free energy barriers to transport within the membrane as equal. This assumption neglects the inherent structural and chemical heterogeneity in polymeric membranes. In this work, we expand the transition-state theory framework to include distributions of membrane free energy barriers. We show that the highest free energy barriers along the most permeable paths, rather than typical paths, provide the largest contributions to the experimentally-observed effective free energy barrier. We show that even moderate, random heterogeneity in molecular barriers will significantly impact how we interpret the mechanisms of transport through membranes. Simplified interpretations of experimentally measured barriers can lead to incorrect assumptions about the underlying mechanisms governing transport and miss the mechanisms most relevant to the overall permeability.
format Preprint
id arxiv_https___arxiv_org_abs_2402_07830
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Interpreting effective energy barriers to membrane permeation in terms of a heterogeneous energy landscape
Schwindt, Nathanael S.
Avidar, Mor
Epsztein, Razi
Straub, Anthony P.
Shirts, Michael R.
Soft Condensed Matter
Chemical Physics
Major efforts in recent years have been directed towards understanding molecular transport in polymeric membranes, in particular reverse osmosis and nanofiltration membranes. Transition-state theory is an increasingly common approach to explore mechanisms of transmembrane permeation with molecular details, but most applications treat all free energy barriers to transport within the membrane as equal. This assumption neglects the inherent structural and chemical heterogeneity in polymeric membranes. In this work, we expand the transition-state theory framework to include distributions of membrane free energy barriers. We show that the highest free energy barriers along the most permeable paths, rather than typical paths, provide the largest contributions to the experimentally-observed effective free energy barrier. We show that even moderate, random heterogeneity in molecular barriers will significantly impact how we interpret the mechanisms of transport through membranes. Simplified interpretations of experimentally measured barriers can lead to incorrect assumptions about the underlying mechanisms governing transport and miss the mechanisms most relevant to the overall permeability.
title Interpreting effective energy barriers to membrane permeation in terms of a heterogeneous energy landscape
topic Soft Condensed Matter
Chemical Physics
url https://arxiv.org/abs/2402.07830