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Thermo- and Light-Responsive Polymers Containing Photoswitchable Azobenzene End Groups

Jochum, FD, zur Borg, L, Roth, PJ and Theato, P (2009) Thermo- and Light-Responsive Polymers Containing Photoswitchable Azobenzene End Groups MACROMOLECULES, 42 (20). pp. 7854-7862.

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Abstract

Telechelic thermo- and light-responsive polymers based on poly(oligo(ethylene glycol) methyl ether methacrylate) P(OEGMA) with azobenzene functionalities at the end groups were synthesized. In a reversible addition-fragmentation chain transfer (RAFT) polymerization using a functionalized chain transfer agent (CTA) containing a pentafluorophenyl (PFP) activated ester, oligo(ethylene glycol) methyl ether methacrylate (OEGMA, Mn ∼ 300 g mol-1 ) could successfully be polymerized with good control over molecular weight, very high conversions, and narrow molecular weight distributions. Polymers derived from this CTA possessed an activated ester at the R-end of the polymer chain as well as a dithioester ω-terminus. The ω-dithioester group of each polymer chain could quantitatively be either removed with AIBN treatment or substituted with a PFP ester by using a modified diazo compound. As a consequence, a postmodifiaction of the telechelic reactive end groups was possible through a polymer analogous reaction with aminofunctionalized azobenzene. P(OEGMA) polymers containing azobenzene end groups showed a reversible light- and temperature-controlled phase transition in water. Higher values for the lower critical solution temperature (LCST) were measured after irradiation of the aqueous polymer solutions due to the higher polarity of cis-azobenzene. The LCST differences between irradiated and nonirradiated solutions increased linearly upon the ratio of azobenzene units up to 4.3 C

Item Type: Article
Subjects : subj_Chemistry
Authors :
AuthorsEmailORCID
Jochum, FDUNSPECIFIEDUNSPECIFIED
zur Borg, LUNSPECIFIEDUNSPECIFIED
Roth, PJUNSPECIFIEDUNSPECIFIED
Theato, PUNSPECIFIEDUNSPECIFIED
Date : 27 October 2009
Identification Number : 10.1021/ma901295f
Copyright Disclaimer : Copyright 2009 American Chemical Society
Uncontrolled Keywords : Science & Technology, Physical Sciences, Polymer Science, POLYMER SCIENCE, TRANSFER RADICAL POLYMERIZATION, FRAGMENTATION CHAIN TRANSFER, AQUEOUS-SOLUTIONS, FUNCTIONALIZED POLYMERS, N-ISOPROPYLACRYLAMIDE, PHASE-TRANSITIONS, SMART POLYMERS, TRANSFER AGENT, RAFT AGENTS, ONE-POT
Related URLs :
Depositing User : Symplectic Elements
Date Deposited : 25 May 2016 13:49
Last Modified : 25 May 2016 13:49
URI: http://epubs.surrey.ac.uk/id/eprint/810825

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