RHEOOPTICAL BEHAVIOR OF WORMLIKE MICELLAR SYSTEMS

Cetyltrimethylammonium bromide, CTAB, forms long wormlike micelles in aqueous solutions with sodium salicylate, NaSal. The system makes an entanglement network similar to concentrated polymer systems, and shows profound viscoelastic behavior highly dependent on concentration of CTAB, C-D, and NaSal, C-S. The system also is strongly flow birefringent. The refractive index tenser and the stress tenser are linearly related by a stress-optical coefficient C = -3.1x10(-8) cm(2)dyn(-1) essentially independent of C-D and C-S. This linearity suggests that the origin of elasticity of the wormlike micellar system is orientation of micellar portions between entanglement points. The sign and magnitude of C is consistent with the proposed structure in which most of CTA(+) ions are arranged in a radial pattern with their molecular axis mostly perpendicular to the axis of the wormlike micelle.