The Role of the Presence of Aliphatic Alcohols on the Formation of Wormlike Micelle of Anionic-Cationic Surfactants Mixture

Abstract

Thermodynamically controlled supramolecular gel or aggregate is commonly resulted from the formation of one-dimensional micelles through specific self-assembling of amphiphilic molecules. This phenomenon is commonly referred to as the formation of worm- or thread-like micelle which is still considered as quite complicated and obscure. This, in spite of the recent physical insight for interpreting this phenomenon, is referred to as the critical intermolecular forces (CIF) of which still needs further support. Therefore, attention by scientists in this field should be given in order to make this transition phenomenon clear. In this work, investigations concerning the effect of addition of aliphatic alcohols with different chain lengths of even carbon numbers (ethanol, 1-butanol, 1-hexanol, 1-octanol and 1-decanol), at different concentrations (0.002-0.040 M), and temperatures on the formation of wormlike micelle for the mixture of anionic sodium dodecylsulfate (SDS) and cationic cetyltrimethylammonium bromide (CTAB) surfactants were carried out. The formation of these one dimensional micelles were practically detected by following the sharp change of physical properties through the presence of a remarkable high viscosity peak. The results indicate there is no linear or systematic relationship between the effects of the presence of these alcohols with their chain lengths. It has been found that the presence of aliphatic alcohols causes a positive effect on the formation of one dimensional micelles. The ability of the transition from spherical to wormlike micelles increases with increasing their concentrations of alcohols except for that of 1-octanol. The obtained achievements were explained in terms of CIF theory which then offered a reasonable support to this theory. It was concluded that alcohols particularly ethanol and 1-octanol can be employed as adjustment reagents for controlling required viscosity of threadlike micelles.