Thermoresponsive Poly(2-oxazoline) Molecular Brushes by Living Ionic Polymerization: Kinetic Investigations of Pendant Chain Grafting and Cloud Point Modulation by Backbone and Side Chain Length Variation
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AbstractMolecular brushes of poly(2-oxazoline)s were prepared by living anionic polymerization of 2-iso-propenyl-2-oxazoline to form the backbone and subsequent living cationic ring-opening polymerization of 2-n- or 2-iso-propyl-2-oxazoline for pendant chain grafting. In situ kinetic studies indicate that the initiation efficiency and polymerization rates are independent from the number of initiator functions per initiator molecule. This was attributed to the high efficiency of oxazolinium salt and the stretched conformation of the backbone, which is caused by the electrostatic repulsion of the oxazolinium moieties along the macroinitiator. The resulting molecular brushes showed thermoresponsive properties, that is, having a defined cloud point (CP). The dependence of the CP as a function of backbone and side chain length as well as concentration was studied. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
CitationZhang N, Luxenhofer R, Jordan R (2012) Thermoresponsive Poly(2-oxazoline) Molecular Brushes by Living Ionic Polymerization: Kinetic Investigations of Pendant Chain Grafting and Cloud Point Modulation by Backbone and Side Chain Length Variation. Macromolecular Chemistry and Physics 213: 973–981. Available: http://dx.doi.org/10.1002/macp.201200015.
SponsorsThis work was supported by the Elitenetzwerk Bayern in the frame of the international graduate school CompInt ("Materials Science of Complex Interfaces") as part of the IGSSE ("International Graduate School for Science and Engineering") at the Technische Universitat Munchen. R.J. thanks for additional support by the Cluster of excellence "Center for Regenerative Therapies Dresden" (CRTD). R. L. was supported by a postdoctoral stipend from the King Abdullah University of Science and Technology (KAUST).