DYNAMICS OF POLY(STYRENE-B-2-VINYLPYRIDINE) IN TOLUENE

Low molecular weight specifically labeled block copolymer poly(beta-de uteriostyrene-b-2-vinylpyridine) (beta-DSVP) and poly(alpha-deuteriost yrene) (alpha-DS) (7600 and 10000 g/mol with polydispersities of 1.15 and 1.7, respectively) have been prepared by anionic polymerization. D euterium NMR relaxation times and self-diffusion coefficients of DSVP and DS were measured for the polymers in solution as a function of con centration. The relaxation times were interpreted through the use of t he Hall-Helfand model for chain dynamics. In toluene, the dynamics of the styrene segments in block copolymers were different-than in homopo lystyrene. The effect of concentration on segmental motions was more p ronounced for the low molecular weight block copolymers than it was fo r 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 bloc k copolymer also showed a sharp decrease at concentrations greater tha n 15 wt %. The changes in the relaxation behavior and self-diffusion c oefficients were attributed to micellization of the block copolymer in toluene. The cmc value was estimated to be 11 wt % based on a pseudop hase model.