Solution behaviour of a random copolymer of poly(isobutyl methacrylate-t-butylaminoethyl methacrylate): 2. Viscosity and light scattering intensity studies

Abstract

Random copolymers of poly(isobutyl methacrylate-t-butylaminoethyl methacrylate) with M w ∼ 2.4 × 10 6 g mol −1 could be shown to form more expanded coils in the very dilute solution regime (≲ 10 −5 g ml −1) due to intramolecular repulsion, to associate in most solvents in the dilute solution regime (∼ 10 −4 g ml −1) where inter- and intramolecular interactions are present, and to aggregate further in semidilute/concentrated solution regimes where intermolecular interactions dominate. The formation of larger aggregates in semidilute/concentrated solutions is responsible for its effectiveness as a polymer additive. At the same time, the rheological properties, such as the shear-rate dependence of the viscosity, tend to become more sensitive to concentration and temperature variations.