Specific Ion Selectivity in Sulfonated Polystyrene Membranes Near the Percolation Threshold

Specific Ion Selectivity in Sulfonated Polystyrene Membranes Near the Percolation Threshold | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Specific Ion Selectivity in Sulfonated Polystyrene Membranes Near the Percolation Threshold Ngai Yin Yip, Yuxuan Huang, Marshall Tekell, Jingchao Qin, Sanat Kumar This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7546567/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Engineering selective transport between ions of the same valence is critical for separations in water, energy, and the environment, but remains technically challenging for ion-exchange membranes (IEMs). In this study, we hypothesize that cation exchange membranes with sufficiently water-poor matrices can leverage differences in the ion dehydration free energy, −Δ G hyd , to enhance selectivity between monovalent alkali metal cations. Thin films of sulfonated polystyrene random copolymers with controlled sulfonation levels were fabricated to tune membrane hydration. Mixed-cation electrodialysis experiments showed increased selectivity for K⁺ over Li⁺ as membrane hydration decreased, while mobility ratios remained unchanged—indicating that preferential sorption of K⁺, with lower −Δ G hyd , governs the preferential transport. Selectivities up to 3.1 were achieved, surpassing commercial IEM benchmarks. However, excessive dehydration below a percolation threshold led to loss of ion transport due to disruption of ion cluster connectivity. These findings provide key structure-property insights into partial ion dehydration and hydration-dependent percolation, informing new design strategies for IEMs with enhanced specific ion selectivity. Physical sciences/Engineering/Chemical engineering Physical sciences/Materials science/Soft materials/Polymers Alkali metal ion selectivity ion-exchange membranes dehydration free energy electrodialysis ionomers X-ray scattering percolation threshold Full Text Additional Declarations There is NO Competing Interest. Supplementary Files NatChemEngspecificionselectivemembraneHuangTekelletalSI20250710.pdf Supplementary Information for Publication Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7546567","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":546894134,"identity":"3c7e88f5-a396-48ea-87a8-cdc2720bd762","order_by":0,"name":"Ngai Yin 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