Thermoresponsive Poly(2-Oxazoline) Molecular Brushes by Living Ionic Polymerization: Modulation of the Cloud Point by Random and Block Copolymer Pendant Chains

Type
Article

Authors
Zhang, Ning
Luxenhofer, Robert
Jordan, Rainer

Online Publication Date
2012-08-10

Print Publication Date
2012-09-26

Date
2012-08-10

Abstract
Molecular brushes (MBs) of poly(2-oxazoline)s were prepared by living anionic polymerization of 2-isopropenyl-2-oxazoline to form the backbone and living cationic ring-opening polymerization of 2-n-propyl-2-oxazoline and 2-methyl-2-oxazoline to form random and block copolymers. Their aqueous solutions displayed a distinct thermoresponsive behavior as a function of the side-chain composition and sequence. The cloud point (CP) of MBs with random copolymer side chains is a linear function of the hydrophilic monomer content and can be modulated in a wide range. For MBs with block copolymer side chains, it was found that the block sequence had a strong and surprising effect on the CP. While MBs with a distal hydrophobic block had a CP at 70 °C, MBs with hydrophilic outer blocks already precipitated at 32 °C. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Citation
Zhang N, Luxenhofer R, Jordan R (2012) Thermoresponsive Poly(2-Oxazoline) Molecular Brushes by Living Ionic Polymerization: Modulation of the Cloud Point by Random and Block Copolymer Pendant Chains. Macromolecular Chemistry and Physics 213: 1963–1969. Available: http://dx.doi.org/10.1002/macp.201200261.

Acknowledgements
This 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).

Publisher
Wiley

Journal
Macromolecular Chemistry and Physics

DOI
10.1002/macp.201200261

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