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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
Author(s) -
Zhang Ning,
Luxenhofer Robert,
Jordan Rainer
Publication year - 2012
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201200015
Subject(s) - cationic polymerization , polymer chemistry , chemistry , side chain , polymerization , living polymerization , oxazoline , living cationic polymerization , grafting , copolymer , chain transfer , ring opening polymerization , polymer , radical polymerization , organic chemistry , catalysis
Molecular 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.