Abstract
The composition (φ) and temperature dependence (T) of the monomeric friction factor (ζ) has been examined for styrene (S) and methyl methacrylate (MMA) in five SMMA diblock copolymers and the corresponding homopolymers. In all cases the degree of polymerization was approximately 150, sufficiently low to ensure that the chain dynamics follow the Rouse model and that the copolymers are far above the order−disorder transition. The five diblock copolymers had styrene compositions of 91, 70, 39, 19, and 9 wt %. Values of an effective friction factor, ζeff, were obtained from measurements of the steady flow viscosity via the Rouse model, whereby ζeff represents an average over the S and MMA contributions. Values of the component friction factors, ζPS and ζPMMA, were extracted from forced Rayleigh scattering tracer diffusion measurements of dye-labeled PS, PMMA, and SMMA chains. In accord with previous studies, ζPMMA in pure PMMA is significantly greater than ζPS in pure PS, whether compared at equal T or equal ...
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