SIZE AND ELECTROPHORETIC MOBILITY OF C14TASAL MICELLES IN AQUEOUS-MEDIA

Spinnable, viscoelastic solutions of tetradecyltrimethylammonium salicylate (C-14TASal) with and without sodium salicylate (NaSal) have been examined by static, dynamic, and electrophoretic light scattering. In aqueous solutions without NaSal, C-14TASal molecules associate into short rodlike micelles at temperatures below 25-degrees-C. Since the external interference effect indicating the intermicellar correlation is strong, short rodlike micelles may pseudolink with each other. While the intermicellar correlation decreases with addition of NaSal, rodlike micelles lengthen and reach 800-1600 nm in 0.1 M NaSal, resulting in the formation of entangled rodlike micelles. Further addition of NaSal diminishes the micelle size, as manifested by a result that micelles in 1 M NaSal are spherical. Electrophoretic mobility examination indicates that, with addition of NaSal, net micelle surface charge is converted from positive to negative through neutral at approximately 0.1 M NaSal. This manifests that specific adsorption and penetration of salicylate ions dominate micelle size and solution behavior such as spinnability and viscoelasticity.