Rheological properties of acrylonitrile—acrylamide—styrene copolymer solutions synthesized by classical and controlled radical polymerizations

Resumo

The results of a comparative study of the rheological properties of acrylonitrile copolymers solutions synthesized by classical and controlled radical polymerizations in aprotic solvents (dimethyl sulfoxide, dimethylformamide, and dimethylacetamide) are presented. The influence of the chemical nature of comonomers (styrene and acrylamide) and their share in the composition of the chain on the viscosity of solutions is discussed. For all copolymers, the viscosity of solutions is determined by a product of the intrinsic viscosity per concentration. In the transition from dilute and semi-dilute solutions to the concentrated solutions, the form of the dependence changes from linear to power-law. The concentrated solutions are non-Newtonian liquids exhibiting viscoelasticity. Copolymer solutions obtained by controlled radical polymerization have a higher viscosity and less pronounced non-Newtonian behavior. The solutions of copolymers with a high comonomer content obtained in dimethylformamide have the lowest viscosity.