The viscoelasticity and self-diffusion were investigated for aqueous solutions of cetyltrimethylammonium bromide (CTAB) containing sodium salicylate (NaSal). The concentration of CTAB,
CD, was equal to that of NaSal,
Cs. This system contains thread-like micelles and exhibits pronounced viscoelastic behavior. The storage modulus,
G′, and loss modulus,
G″, could be fitted with the Maxwell model of one relaxation time when
CD<0.5M. The plateau modulus,
GN, was proportional to
CD2 over a wide range of
CD. This property is similar to that of concentrated polymer solutions. The relaxation time, τ, was evaluated from the frequency at which
G″ takes maximum. The self-diffusion coefficient,
D, was measured by forced Rayleigh scattering measurement. The quantities
D and τ
-1 varied in a similar manner as a function of
CD ; when
CD<0.2M, they increased with
CD and when
CD<0.2M, they decreased with
CD. This behavior is remarkably different from polymer solutions.The rate of diffusion may be controlled by the rate of the process where thread-like micelles cut across each other, a process proposed previously to describe the stress relaxation.
抄録全体を表示