Structures of PEP–PEO Block Copolymer Micelles: Effects of Changing Solvent and PEO Length and Comparison to a Thermodynamic Model

Grethe Vestergaard Jensen, Qing Shi, G. Roshan Deen, Kristoffer Almdal, Jan Skov Pedersen

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    Structures of poly(ethylene propylene)–poly(ethylene oxide) (PEP–PEO) block copolymer micelles were determined from small-angle X-ray scattering and static light scattering and compared to predictions from a thermodynamic model. Both the corona block length and the solvent water–ethanol ratio were changed, leading to a thorough test of this model. With increasing ethanol fraction, the PEP core–solvent interfacial tension decreases, and the solvent quality for PEO changes. The weight-average block masses were 5.0 kDa for PEP and 2.8–49 kDa for PEO. For the lowest PEO molar mass and samples in pure water (except for the highest PEO molar mass), the micelles were cylindrical; for other conditions they were spherical. The structural parameters can be reasonably well described by the thermodynamic model by Zhulina et al. [Macromolecules2005, 38 (12), 5330–5351]; however, they have a stronger dependence on solvent composition and PEO molar mass than predicted.
    Original languageEnglish
    JournalMacromolecules
    Volume45
    Issue number1
    Pages (from-to)430-440
    ISSN0024-9297
    DOIs
    Publication statusPublished - 2012

    Keywords

    • Small angle X-ray scattering
    • Organic solvents
    • Water-ethanol
    • Thermodynamic properties
    • Solvents
    • Thermodynamic model
    • Solvent composition
    • Block copolymers
    • Propylene
    • Pure water
    • Polyethylene oxides
    • Static Light Scattering
    • Scattering
    • Block copolymer micelles
    • X ray scattering
    • Micelles
    • Structural parameter
    • Block lengths
    • Solvent quality
    • Ethylene
    • Ethanol

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