Viscoelastic Behaviors of Surfactant Threadlike Micellar Solutions. Effects of Additives. 2.

The effects of additives in aqueous threadlike micellar systems formed with cetyltrimethylammonium bromide (CTAB) were studied by means of dynamic viscoelastic and 1H-NMR techniques. Additives were ionic aromatic compound, sodium p-toluenesulfonate (NapTS), and noionic ones / styrene (St) , and toluene (Tol). When a ratio (CS/CD) of the concentration of NapTS (CS) to the concentration of CTAB (CD) was 0.3, 0.4, and 0.5, the longest relaxation time (τm) became longer with increasing St (or Tol) concentration [St] (or [Tol]). This suggests that St (or Tol) interacts with CTA+ at the micellar surface and a threadlike micelle grows longer as [St] (or [Tol]) increases. When CS/CD = 1, τm became shorter with increasing [St] (or [Tol]). This finding suggests that St (or Tol) is solubilized in the deep interior of threadlike micelles and the mechanical strength of threadlike micelles becomes weak with [St] (or [Tol]).