The Effect of Hofmeister Salts on the LCST Transition of Poly(2-oxazoline)s with Varying Hydrophilicity

Authors

  • Meta M. Bloksma,

    1. Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
    2. Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
    3. Laboratory of Organic and Macromolecular Chemistry, Friedrich-Schiller-Universität Jena, Humboldtstrasse 10, 07743 Jena, Germany; www.iomc.uni-jena.de
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  • Daniël J. Bakker,

    1. Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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  • Christine Weber,

    1. Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
    2. Laboratory of Organic and Macromolecular Chemistry, Friedrich-Schiller-Universität Jena, Humboldtstrasse 10, 07743 Jena, Germany; www.iomc.uni-jena.de
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  • Richard Hoogenboom,

    Corresponding author
    1. Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
    2. Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
    • Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands. www.schubert-group.com
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  • Ulrich S. Schubert

    1. Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
    2. Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands
    3. Laboratory of Organic and Macromolecular Chemistry, Friedrich-Schiller-Universität Jena, Humboldtstrasse 10, 07743 Jena, Germany; www.iomc.uni-jena.de
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Abstract

The influence of Hofmeister salts was investigated on the cloud point of three poly(2-oxazoline)s, namely poly(2-ethyl-2-oxazoline) [PEtOx], poly(2-n-propyl-2-oxazoline) [PnPropOx], and poly(2-isopropyl-2-oxazoline) [PiPropOx]. In addition, a comb polymer based on oligo-2-ethyl-2-oxazoline side chains and a methacrylate backbone (POEtOxMA) was included in this investigation. It was found that the ionic response of the poly(2-oxazoline)s strongly depends on their hydrophilicity. The comb polymer POEtOxMA revealed a strikingly similar response to the salts as linear PEtOx even though the cloud points of the polymers in water differ. This indicates that the architecture does not significantly influence the effect of the Hofmeister ions, even though there is a difference in the absolute cloud point.

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