Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (8): 1535-1540.doi: 10.3866/PKU.WHXB201506161

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Self-Assembly of Cationic/Anionic Surfactants with Highly Dissymmetric Lengths of Alkyl Tails

Wen-Jing. DONG,Jian-Xi. ZHAO()   

  • Received:2015-04-16 Published:2015-08-12
  • Supported by:
    the National Natural Science Foundation of China(21273040);the National Natural Science Foundation of China(21473032)

Abstract:

By introducing a new method of solution preparation, systems of equimolar mixing cationic/anionic surfactants with dissymmetric lengths of alkyl tails were investigated using light scattering, rheology, and freezing-fracture transmission electron microscopy (FF-TEM) measurements, in which the cation was docosyltrimethylammobium bromide (C22TABr) and the anions were sodium alkylcarboxylates (Cn-1COONa, n = 4, 6, 8, 10, 12, 14, 16). The results showed that spherical micelles were favored when the cationic/anionic surfactants had highly dissymmetric length tails (C22/n4). With decreasing dissymmetry of the alkyl tail lengths, the aggregates transformed to rod-like micelles, worm-like micelles, and finally vesicles. In the vesicle-formed cases, the size of the aggregate considerably increased with decreasing dissymmetry of the alkyl tail lengths. By analyzing the mechanism of aggregation, the geometry of the cation/anion pair is thought to determine the morphology and the transition of aggregates.

Key words: Cat/anionic surfactants, Dissymmetry of alkyl tail lengths, Aggregate morphology, I on-pair geometry

MSC2000: 

  • O648