Rheological Properties of Solutions of a Polyampholytic Block Copolymer

Steady shear flow behavior as well as dynamic viscoelsticicity was investigated for solutions of a polyampholytic block copolymer. Benzyl alcohol solutions of the polymer show behavior common to usual polymer solutions, whereas the aqueous solutions form transient networks at short times. Shear thickening and shear thinning emerge on the flow curves of the aqueous solutions at high shear rates. Curves of dynamic loss modulus (G”) for the aqueous solutions move to the long time side by the application of steady shear. The increase in relaxation intensity also occurs by shear. The shift of the G” curves to the long time side disappears but a long time is required for the recovery. The origin of the shear thickening is related not only to the shift of the curves but also to the increase in relaxation intensity. These changes on the G” curves are originated from a developed microphase separation under shear flow.