EFFECT OF HOMOPOLYMER HOST CHAIN RELAXATIONS ON THE TRANSLATIONAL DIFFUSION OF A DIBLOCK COPOLYMER

The effect of the dynamics of polystyrene (PS) host chains on the over all translational diffusion of a diblock copolymer of polystyrene and polymethacrylate (ps-b-pmma) of degree of polymerization, N-c = 262, w as investigated. Measurements of the diffusion coefficient of the dibl ock copolymer, Dps-pmma, into PS hosts of varying molecular weight, P, were performed using forward recoil spectrometry. These diffusion coe fficients were orders of magnitude less than those of PS chains of the same degree of polymerization diffusing into the same environments. W hile Dps-pmma(PS) was independent of P for P > 2 x 10(5), it increased for P < 2 x 10(5). These results are interpreted in light of constrai nt release models. (C) 1998 Elsevier Science B.V. All rights reserved.