Viscoelastic Behavior of Aqueous Solutions of Charged Hybrid Threadlike Micelles

We investigated the linear and non-linear viscoelastic behavior of aqueous solutions of hybrid threadlike micelles formed by cetyltrimethylammonium poly (p-vinylbenzoate) (CTAPVB) and some additive simple salts at various pH values. The system showed marked viscoelasticity at lower pH values ca. 2.5. The obtained mechanical relaxation time of the system was proportional to the molecular weight of the incorporated CTAPVB, and lengthened strongly depending on the species of anions in the order of the Hofmeister series. Remarkable stress overshoot phenomena related to strain-hardening were observed under start-up shear flow experiments at high shear rates. Distinct shear-thickening never found in the previously studied threadlike micellar systems was observed in the system. The essential mechanism for viscoelastic behavior unique to the present hybrid threadlike micellar system was discussed.