CROSSOVER EFFECTS ON THE OSMOTIC-PRESSURE AND THE DIFFUSION-COEFFICIENT IN MODERATELY CONCENTRATED POLYMER-SOLUTIONS

The effects of a finite volume fraction of polymer on the reduced osmo tic pressure and the reduced diffusion coefficient in solutions, cover ing an extended concentration range, are analysed in the framework of a recent theoretical approach, which incorporates a renormalization gr oup treatment of a modified interaction Hamiltonian. The resulting ana lytical functions are consistent with the large amount of experimental data accumulated from the literature. In the interpretation of the di ffusion behaviour, over a large concentration interval, the concept of hydrodynamic screening plays a crucial role in obtainig a uniform pic ture. In the region of strongly overlapping chains a breakdown of the universal features of the reduced osmotic pressure and the reduced dif fusion coefficient can be inferred from the theoretical relations.