HYDRODYNAMIC SCALING OF VISCOSITY AND VISCOELASTICITY OF POLYMER-SOLUTIONS, INCLUDING CHAIN ARCHITECTURE AND SOLVENT QUALITY EFFECTS

This paper examines the dependence of polymer solution viscosity eta and higher viscoelastic parameters (e.g., gamma(r), J(e)(0)) on polymer concentration, molecular weight, chain architecture, and solvent quality. For solutions of linear chains, a transition from a solutionlike (stretched-exponential) to meltlike (power-law) dependence of eta on c or M occurs at c[eta] much greater than 1, and sometimes c[eta] > 100. The hydrodynamic scaling description of polymer transport coefficients remains applicable to concentrations far above the overlap concentration c[eta] approximate to 1. Star polymers remain in the solutionlike regime at c and M far above the c and M at which linear chains show a transition to meltlike behavior. Other viscoelastic parameters, notably gamma(r) and J(e)(0), have the same c and M dependences (stretched exponential at fewer (c, M), power law at larger (c, M)) that eta does, with the same solutionlike-meltlike transition concentration for all three parameters. If eta for a single polymer in a series of solvents is fit to exp(alpha c(nu)), the several-fold variation in alpha at fixed M is almost entirely accounted for by the dependence of alpha on solvent quality, as expressed by the chain expansion parameter alpha(eta). Experiment is consistent with the alpha similar to alpha(eta)(3) here shown to be predicted by the hydrodynamic scaling model (Phillies, G. D. J. Macromolecules 1987, 20, 558).