Dilute polymer solutions: Internal viscosity, dynamic scaling, shear thinning and frequency-dependent viscosity

Following an idea of de Gennes about the origin of internal viscosity in dilute polymer solutions, we estimate the dissipation produced by monomer-solvent and direct monomer-monomer friction due to large-loop intrapolymer contacts. While for 6 solvents both contributions scale with the same power of molecular weight, in good solvents they scale differently indicating that intemal-friction effects may explain the observed deviations from dynamic scaling. Using the dynamic blob model, we infer the empirical Cox-Merz rule, predict the high frequency- shear-rate-dependence of the intrinsic viscosity for both 6 and good solvents and calculate the critical generalized Weissenberg number at which the viscosity becomes dominated by internal friction. Finally, we propose an expression for the spectrum of relaxation times which interpolates smoothly between the zero- and the high-frequency shear- rate limits. A preliminary analysis shows qualitative and, in several cases, quantitative agreement with known experimental results and new experiments are proposed to further test our theory.