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Thermo-responsive Poly(methyl methacrylate)-block-poly(N-isopropylacrylamide) Block Copolymers Synthesized by RAFT Polymerization: Micellization and Gelation

✍ Scribed by Tian Tang; Valeria Castelletto; Petros Parras; Ian W. Hamley; Stephen M. King; Debashish Roy; Sebastien Perrier; Richard Hoogenboom; Ulrich S. Schubert

Publisher
John Wiley and Sons
Year
2006
Tongue
English
Weight
205 KB
Volume
207
Category
Article
ISSN
1022-1352

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✦ Synopsis

Abstract

Summary: RAFT polymerization was used to prepare PMMA‐b‐PNIPAM copolymers. Two different chain transfer agents, tBDB and MCPDB, were used to mediate the sequential polymerizations. Micellar solutions and gels were prepared from the resulting copolymers in aqueous solution. When heated above T~c~ of PNIPAM (about 31 °C), DLS revealed that PNIPAM coronas collapsed, resulting in aggregation of the original micelles. The micellar gels underwent syneresis above T~c~ as water was expelled from the ordered gel structure, the lattice periodicity of which was determined by SANS. A large decrease in lattice spacing was observed above T~c~. The gel became more viscoelastic at high temperature, as revealed by shear rheometry which showed a large increase in G″.
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