Dually responsive multiblock copolymers via reversible addition- fragmentation chain transfer polymerization: Synthesis of temperature- and redox-responsive copolymers of poly(N-isopropylacrylamide) and poly(2-(dimethylamino)ethyl methacrylate)

Ye Zi You, Qing Hui Zhou, Devika Soundara Manickam, Lei Wan, Guang Zhao Mao, David Oupický

Research output: Contribution to journalArticlepeer-review

92 Scopus citations

Abstract

We report the synthesis of temperature- and redox-responsive multiblock copolymers by reversible addition-fragmentation chain transfer (RAFT) polymerization. Well-defined α,ω-bis(dithioester)-functionalized poly(N-isopropylacrylamide) (PNIPAM) and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) were prepared using 1,4-bis(thiobenzoylthiomethyl) benzene and 1,4-bis(2-(thiobenzoylthio)prop-2-yl)benzene as RAFT agents, respectively. Dually responsive multibrock copolymers were synthesized in a single aminolysis/oxidation step from the α,ω-bis(dithioester)- terminated PNIPAM and PDMAEMA. The copolymers and their stimulusresponsive behavior were characterized by size exclusion chromatography, NMR, light scattering, and atomic force microscopy. Because of the presence of redox-sensitive disulfide bonds between the blocks, the copolymers were readily reduced to the starting polymer blocks. The presence of temperature-responsive PNIPAM blocks provided copolymers with the ability to assemble into core-shell nanostructures with hydrophobic PNIPAM as the core and eationic PDMAEMA as the stabilizing shell when above the phase transition temperatures of PNIPAM. The temperature-induced assembly of the copolymers also showed substantial pH sensitivity. The phase transition temperature increased with decreasing pH, while the molecular weight of the assemblies decreased.

Original languageEnglish (US)
Pages (from-to)8617-8624
Number of pages8
JournalMacromolecules
Volume40
Issue number24
DOIs
StatePublished - Nov 27 2007

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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