Solvation-Solvophobicity Interplay Drives Reentrant Swelling of Polymers in Poor Solvent Mixtures

Solvation-Solvophobicity Interplay Drives Reentrant Swelling of Polymers in Poor Solvent Mixtures | 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 Solvation-Solvophobicity Interplay Drives Reentrant Swelling of Polymers in Poor Solvent Mixtures Dong Meng, Chinmoy Saha, Xiangyu Zhang, Md Masrul Huda, Neeraj Rai This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7235615/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract While it is well established that a delicate balance between hydration and hydrophobic interactions governs the functional structures of proteins, a similar principle has received comparatively little attention in explaining the often-counterintuitive solution behavior of chemically simple synthetic polymers in mixed solvent environments. Using poly(methyl methacrylate) (PMMA) in water/tert-butanol mixtures as a model system, we demonstrate that the interplay between hydration and hydrophobicity can induce reentrant swelling of PMMA --- even though both water and tert-butanol are individually poor solvents for the polymer. Atomistic simulations reveal that changes in solution density upon mixing, previously proposed as a key driver of reentrant swelling, have negligible impact on PMMA conformation. Instead, the observed swelling correlates with a transition in local solvent composition -- from bulk-like to water-deficient -- regulated by a shifting balance between hydration and hydrophobic interactions associated with PMMA’s ester and alkyl groups, respectively. A theoretical model, informed by simulation insights, identifies two key effects arising from this interplay that drive the reentrant behavior: (1) the decoupled responses of hydration and hydrophobicity to solvent composition, and (2) composition-dependent effective repulsions between polymers, mediated by hydration-modulated hydrophobic interactions. These findings point to a general mechanism by which polymers bearing both solvation-prone and solvophobic moieties can exhibit cosolvency in mixed solvents, underscoring the critical role of solvation–solvophobicity interplay in governing polymer behavior in complex solution environments. Physical sciences/Materials science/Soft materials/Polymers Physical sciences/Materials science/Theory and computation/Atomistic models Physical sciences/Materials science/Theory and computation/Coarse-grained models Physical sciences/Chemistry/Polymer chemistry/Polymer characterization Full Text Additional Declarations There is NO Competing Interest. Supplementary Files Supporting.pdf Supporting Materials Cite Share Download PDF Status: Posted 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-7235615","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":497611647,"identity":"9600379f-7e6c-4c62-b7ae-8c25cfe797ae","order_by":0,"name":"Dong 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Using poly(methyl methacrylate) (PMMA) in water/tert-butanol mixtures as a model system, we demonstrate that the interplay between hydration and hydrophobicity can induce reentrant swelling of PMMA --- even though both water and tert-butanol are individually poor solvents for the polymer. Atomistic simulations reveal that changes in solution density upon mixing, previously proposed as a key driver of reentrant swelling, have negligible impact on PMMA conformation. Instead, the observed swelling correlates with a transition in local solvent composition -- from bulk-like to water-deficient -- regulated by a shifting balance between hydration and hydrophobic interactions associated with PMMA’s ester and alkyl groups, respectively. 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