Experimental test of renormalization-group calculations on the universality of dilute-solution polymer dynamics

Abstract

Recent renormalization-group calculations by Wang et al. predict a strong coupling between the hydrodynamic and excluded-volume interactions of polymer chain dynamics in good solvents. The predictions were tested here by examining the dependences of the chain expansion factor ratios α H α S , α 3 η α 3 S and α 3 η α 2 S α H on the excluded-volume parameter z in its large region. Well documented experimental data for five polyisoprene samples were available since the samples behaved more like a model of flexible linear polymers in dilute solution than does polystyrene. With experimental α 3 S extending up to a value as large as 13, it was found that, contrary to the predictions, α 3 η α 2 S α H did not show a constant value, which was predicted to be universal, irrespective of polymer species and solvents used, but decreased sharply with increasing α 3 S. No draining effect was detected clearly. Rather this experimental trend could be satisfactorily compared with the result obtained from simple extrapolation of Ganazzoli et al.'s self-consistent Fourier configurational calculation (with non-draining limit) to large α S.