: The role of surfactants head group in the formation of self-assembled supramolecular aggregate
: Rabah Ali Khalil
: Volume 2 (2015)
: Thermodynamically controlled supramolecular gel or aggregate is commonly resulted from the formation of one-dimensional micelles through specific self-assembling of amphiphilic molecules. Up to present date, the role of surfactant head group in the formation of such a condensed matter is still obscure. Consequently, this work presents a study of the effect of changing surfactant head group on the transformation phenomenon towards one dimensional shape of aggregate. Binary mixture of anionic sodium dodecylsulfate (SDS) and cationic cetylpyridinium chloride (CPC) has been examined for comparison with previously published SDS with cetyltrimethylammonium bromide (CTAB). The work has been extended through using ternary mixtures of SDS, CPC and CTAB at 1:1, 3:1 and 1:3 CTAB:CPC ratios. The thermodynamic properties have been determined for all of these mixtures. The results indicate that the presence of pyridinum cation in CPC surfactant causing a bad effect on the formation of wormlike micelle in contrast to that of trimethylammonium in CTAB. It has been suggested that the formation of supramolecular gel depends on ionization potential of the surfactant head group as needed for head to head electrostatic interaction through the construction of one dimensional shape of aggregate. It has been generally concluded that hydrophilic effect plays a sensible part in the formation of wormlike micelles in contrast to that of hydrophobic which plays the major role and hence supporting the critical intermolecular forces theory.