Dynamics of Poly(styrene-b-2-vinylpyridine) in Toluene
Low molecular weight specifically labeled block copolymer poly(β-deuteriostyrene-b-2-vinylpyridine) (β-DSVP) and poly(α-deuteriostyrene) (α-DS) (7600 and 10000 g/mol with polydispersities of 1.15 and 1.7, respectively) have been prepared by anionic polymerization. Deuterium NMR relaxation times and self-diffusion coefficients of DSVP and DS were measured for the polymers in solution as a function of concentration. The relaxation times were interpreted through the use of the Hall-Helfand model for chain dynamics. In toluene, the dynamics of the styrene segments in block copolymers were different than in homopolystyrene. The effect of concentration on segmental motions was more pronounced for the low molecular weight block copolymers than it was for the homopolymer above 15 wt %. The results indicated that the short-range motions were similar for the homo- and copolymer while the long-range motions were different. Self-diffusion coefficients for the block copolymer also showed a sharp decrease at concentrations greater than 15 wt %. The changes in the relaxation behavior and self-diffusion coefficients were attributed to micellization of the block copolymer in toluene. The cmc value was estimated to be 11 wt % based on a pseudophase model.
M. Xie and F. D. Blum, "Dynamics of Poly(styrene-b-2-vinylpyridine) in Toluene," Macromolecules, American Chemical Society (ACS), Jan 1996.
The definitive version is available at http://dx.doi.org/10.1021/ma9512162
Article - Journal
© 1996 American Chemical Society (ACS), All rights reserved.