Nanoconfinement and Chemical Structure Effects on Permeation Selectivity of Self-Assembling Graft Copolymers

Chiara Vannucci, Ikuo Taniguchi, Ayse Asatekin

    Research output: Contribution to journalArticlepeer-review

    9 Citations (Scopus)

    Abstract

    Permeation of small molecule solutes through thin films is typically described by the solution-diffusion model, but this model cannot predict the effects of nanostructure due to self-assembly or additives. Other models focusing on diffusion through isolated nanopores indicate that confining permeation to channels slightly larger than the size of the solute can lead to an increased influence of solute-pore wall interactions on permeation rate. In this study, we analyze how differences in polymer nanostructure affect the relative contributions of solute size and polymer-solute interactions on transport rate. We compared the diffusion rates of several small molecules through two polymer thin films: A cross-linked, homogeneous film of poly(ethylene glycol phenyl ether acrylate) (PEGPEA) and a graft copolymer with a poly(vinylidene fluoride-co-chlorotrifluoroethylene) (P(VDF-co-CTFE)) backbone and PEGPEA side chains that self-assemble into continuous ∼1-3 nm PEGPEA domains through which transport occurs. We correlated these rates with the size of each solute and its chemical affinity to PEGPEA, as measured by the difference between their solubility parameters. Diffusion rate through the homogeneous polymer film was controlled by solute size, whereas diffusion rate through the copolymer was strongly controlled by the difference between the solubility parameters. Furthermore, permeation selectivity between two selected molecules was 2.5× higher for the nanostructured copolymer, likely enhanced by the nanoconfinement effects. These initial results indicate that polymer self-assembly is a promising tool for designing polymeric membranes that can differentiate between solutes of similar size but differing chemical structures.

    Original languageEnglish
    Pages (from-to)872-878
    Number of pages7
    JournalACS Macro Letters
    Volume4
    Issue number9
    DOIs
    Publication statusPublished - Sep 15 2015

    All Science Journal Classification (ASJC) codes

    • Organic Chemistry
    • Polymers and Plastics
    • Inorganic Chemistry
    • Materials Chemistry

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