Crossover effects on the osmotic pressure and the diffusion coefficient in moderately concentrated polymer solutions

Abstract

The effects of a finite volume fraction of polymer on the reduced osmotic pressure and the reduced diffusion coefficient in solutions, covering an extended concentration range, are analysed in the framework of a recent theoretical approach, which incorporates a renormalization group treatment of a modified interaction Hamiltonian. The resulting analytical functions are consistent with the large amount of experimental data accumulated from the literature. In the interpretation of the diffusion behaviour, over a large concentration interval, the concept of hydrodynamic screening plays a crucial role in obtaining a uniform picture. In the region of strongly overlapping chains a breakdown of the universal features of the reduced osmotic pressure and the reduced diffusion coefficient can be inferred from the theoretical relations.