Correlation between solution and gel properties of copolymers of acrylamide and diallyldimethylammonium chloride

Several copolymers formed by acrylamide and diallyldimethyl ammonium chloride containing different fractions of charged diallyl residues, x, were synthesized. Solution properties of linear samples of these copolymers were studied by size exclusion chromatography coupled to differential refractive index and light scattering detectors, which allowed the determination of molecular weight averages, molecular dimensions, scaling law coefficients, and unperturbed dimensions. The results were compared with those of the corresponding homopolymers i.e., polyacrylamide and poly(diallyldimethylammonium chloride). On the other hand, crosslinked samples of the copolymers were prepared and their swelling in water was studied. The correlation between the solution properties of the linear samples and the swelling behaviour of their crosslinked counterparts can be illustrated through the relationship between the characteristic ratio of the unperturbed dimensions and the equilibrium degree of swelling since both magnitudes exhibit a similar dependence on x. Moreover, this dependence is not linear and it passes through a maximum at ca. x ≈ 0.5.