Electrostatic long-range interactions in macromolecules of flexible-chain linear polyelectrolytes with low charge density in aqueous solutions of different ionic strength

The methods of molecular hydrodynamics (translational diffusion, velocity sedimentation, viscometry) have been used to study copolymers of N‑methyl-N‑vinylacetamide and N‑methyl-N‑vinylamine hydrochloride with an average content of charged groups (4,4 ± 0,2) mol.% in aqueous 0,2 M NaCl solution. Kuhn-Mark-Houwink-Sakurada scaling relations were obtained. Viscous flow was studied in the widest possible range of ionic strengths of aqueous solutions, from salt-free to 6 M NaCl. The data got were compared with those previously obtained for neutral poly-N‑methyl-N‑vinylacetamide. It was firstly shown experimentally that the character of the dependence of the intrinsic viscosity on the molecular weight of a copolymer of such composition in solutions of minimal ionic strength is typical for the chains exhibiting intrachain volume effects, i.e. electrostatic long-range interactions.