Sorption kinetics of methanol in thin poly(methyl methacrylate) films studied by optical reflectivity

Koichiro Hori, Hisao Matsuno, Keiji Tanaka

    Research output: Contribution to journalArticlepeer-review

    22 Citations (Scopus)

    Abstract

    To study the thickness dependence of methanol diffusion into poly(methyl methacrylate) (PMMA) films, an experimental method based on optical reflectivity was proposed. The method can cover a thickness range from the micrometre down to the nanometre scale using a single set-up. Methanol molecules diffuse into PMMA following a Case II mechanism in which they induce segmental motion of the matrix polymer. We observed two diffusion modes, fast and slow, assignable respectively to the outermost layer and the remaining internal region including the substrate interface. When the film becomes thinner, the ratio of the interfacial area to the total volume increases. This results in slowing down of the methanol diffusion due to the contribution of the depressed segmental mobility at the substrate interface. Interestingly, the thickness of the mobility-enhanced layer at the outermost region of the film similarly decreased with decreasing total thickness owing to the effect of the substrate interface.

    Original languageEnglish
    Pages (from-to)10319-10326
    Number of pages8
    JournalSoft Matter
    Volume7
    Issue number21
    DOIs
    Publication statusPublished - Nov 7 2011

    All Science Journal Classification (ASJC) codes

    • Chemistry(all)
    • Condensed Matter Physics

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