A series of linear poly(acrylamide-co-acrylates) (PAAm/AAcNa) has been prepared covering a copolymer composition between 0 and 96.3 tool0/0 acrylate units, which have the same degrees of polymerization and chain length distributions. Measurements of viscosity and light scattering have proven that maximum coil dimensions of PAAm/ AAcNa in salt solutions are achieved at about 67 mole-% AAcNa. This so-called maximum behaviour was researched by measuring the radius of gyration, second virial coefficient, molecular weight, preferential solvation, viscosity and absorption bands of the copolymer series. Thus, an increase in the possible ways of arranging AAcNa-AAmAAcNa units (via H-bonds) will lead to extended coil dimensions and therefore influence the viscosity. In addition, it can therefore be concluded from all these results that the maximum behaviour is real and not influenced by the different distributions of the samples. The copolymer composition can be easily determined by infra-red spectroscopy by use of a proposed relation.