Nonlinear rheology of aqueous solutions of thread-like micelles of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) were investigated. The concentration of CTAB was fixed at 0.1 mol 1^-1, and the concentration of NaSal was varied from 0.07 to 0.4 mol 1^-1. For all test solutions, dynamic moduli were described with the Maxwell model having a single relaxation time, t. Time evolutions of the shear stress, σ, and the first normal stress difference, N₁, after inception of the steady shear flow were measured. For all test solutions, strain-hardening was observed and a and N₁ diverged at a certain strain when the shear rate, y, exceeded a critical rate being larger than T^-1. A simple relationship for elastic solids, N₁/σ = γ with γ being the strain imposed by shear flow, held for all the solutions in the strain-hardening regime. The strain-hardening was attributable to the strain dependent shear modulus and well described with the network theory considering finite extensibility of network strands. The segment size of network strand was successfully determined. Creep response of the solutions was also measured. At higher stress level than the plateau modulus, recoverable compliance was considerably increased, suggesting shear-induced structural changes.

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Amphiphilic polyelectrolytes or hydrophobically modified polyelectrolytes undergo hydrophobically driven self-association in aqueous media to form, in some cases, well-defined spatial structures on a nanometer scale (nanostructures). This depends strongly on their macromolecular architectures. This review is concerned with recent advances in the studies of amphiphilic block and random polyelectrolytes, including fundamental aspects of the self-association of amphiphilic polyelectrolytes. Extensive studies by a large number of research groups have so far yielded a good deal of progress in the fundamental understanding of underlying structure-property relationships in the self-association of amphiphilic polyelectrolytes in aqueous media. This review particularly focuses on solution properties of some amphiphilic polyelectrolytes that exhibit stimuli-responsiveness, which may find applications in various commercial products.

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