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

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

Abstract:

RAFT polymerization was used to prepare PMMA-b-PNIPAMcopolymers. 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 Tc of PNIPAM (about 31 8C), DLS revealed that PNIPAM coronas collapsed, resulting in aggregation of the original micelles. The micellar gels underwent syneresis above Tc 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 Tc. The gel became more viscoelastic at high temperature, as revealed by shear rheometry which showed a large increase in G00.

Year:

2006

Type of Publication:

Article

Journal:

Macromolecular Chemistry and Physics

Volume:

207

Pages:

1718 - 1726