Temperature and pressure dependence of the order parameter fluctuations, conformational compressibility, and the phase diagram of the PEP-PDMS diblock copolymer

D. Schwahn, H. Frielinghaus, K. Mortensen, K. Almdal

    Research output: Contribution to journalJournal articleResearch

    Abstract

    The structure factor of a poly(ethylene-propylene)-poly(dimethylsiloxane) diblock copolymer has been measured by small-angle neutron scattering as a function of temperature and pressure. The conformational compressibility exhibits a pronounced maximum at the order-disorder phase transition. The phase boundary shows an unusual shape. With increasing pressure it first decreases and then increases. Its origin is an increase, respectively, of the entropic and of the enthalpic part of the Flory-Huggins interaction parameter. The Ginzburg parameter describing the limit of the mean-field approximation is not influenced by pressure.
    Original languageEnglish
    JournalPhysical Review Letters
    Volume77
    Issue number15
    Pages (from-to)3153-3156
    ISSN0031-9007
    DOIs
    Publication statusPublished - 1996

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