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International Journal of Polymer Science
Volume 2013 (2013), Article ID 196145, 9 pages
http://dx.doi.org/10.1155/2013/196145
Research Article

Thermoresponsive and Redox Behaviors of Poly(N-isopropylacrylamide)-Based Block Copolymers Having TEMPO Groups as Their Side Chains

Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan

Received 18 April 2013; Revised 24 May 2013; Accepted 10 June 2013

Academic Editor: Haojun Liang

Copyright © 2013 Toru Uemukai et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Thermoresponsive and redox-active block copolymers having 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) moieties have been synthesized by using the reversible addition-fragmentation chain transfer (RAFT) polymerization technique. N-Isopropylacrylamide (NIPAAm) and 2,2,6,6-tetramethylpiperidyl methacrylate (TEMPMA) monomers were copolymerized stepwise under RAFT polymerization conditions to afford the thermoresponsive block copolymers, PNIPAAm-block-PTEMPMA and PNIPAAm-block-PTEMPMA-block-PNIPAAm. Oxidation of tetramethylpiperidine groups in the copolymers successfully afforded the corresponding TEMPO-containing block copolymers. The resulting triblock copolymer was found to be thermoresponsive showing lower critical solution temperature (LCST) at 34C in its aqueous solution. Redox behavior of the resulting copolymer was observed by cyclic voltammetry. The potential of anodic current peak changed below and above the LCST of the block copolymer. These results indicate that the phase transition of thermoresponsive polymer influences the redox potential of TEMPO moieties.