The coupling model is formulated in terms of the dynamic constraint entropy, Sc(t), and subsequently compared with measured tracer diffusion coefficients D for linear, 3‐arm star, and 12arm star polystyrenes in solutions of poly (vinyl methyl ether) (PVME) /o‐fluorotoluene. Inequalities between the dynamic constraint entropies, Scf and Scf′(t), respectively, for f‐arm and f′‐arm stars, enable us to explain the experimental observation that at constant arm molecular weight, the ratio Dstar/Dlinear decreases substantially with increasing concentration above the entanglement concentration for the PVME. This work indicates that not only the reptation model, but also the coupling model, can account for the experimental observation that in entangled solutions the mechanism for diffusion depends on diffusant architecture.
|Original language||English (US)|
|Number of pages||11|
|Journal||Journal of Polymer Science Part B: Polymer Physics|
|State||Published - Jul 1990|