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Thermo‐responsive Poly(methyl methacrylate)‐ block ‐poly( N ‐isopropylacrylamide) Block Copolymers Synthesized by RAFT Polymerization: Micellization and Gelation
Author(s) -
Tang Tian,
Castelletto Valeria,
Parras Petros,
Hamley Ian W.,
King Stephen M.,
Roy Debashish,
Perrier Sebastien,
Hoogenboom Richard,
Schubert Ulrich S.
Publication year - 2006
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.200600309
Subject(s) - copolymer , polymer chemistry , raft , micelle , polymerization , chain transfer , materials science , reversible addition−fragmentation chain transfer polymerization , methyl methacrylate , syneresis , aqueous solution , chemistry , radical polymerization , polymer , organic chemistry , composite material
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 ″.