Preparation, Characterization and Measurement of CMC of SDS, CTAB and Tween 80 Based Self-Assembled Aggregates in W/O and O/W Microemulsions as Systems for Preparing Nanomaterials

Abstract

Series of water in oil (w/o) composition of microemulsions were prepared from systems with sodium dodecyl sulphate (SDS), 1-butanol, cyclohexane, water; tween 80, 1-butanol, cyclohexane, water and cetyltrimethylammonium bromide (CTAB), 1-butanol, cyclohexane, water; at varying water to surfactant mole ratio, w0 and oil in water (o/w) composition of SDS and CTAB based microemulsions were made at reconcile with composition of w/o microemulsions. Micelles and reverse micelles are dominant form of self-assembled aggregates in o/w microemulsions and w/o microemulsions respectively. The ability of these aggregates to solubilize water had been employed for the detection of the critical micellization concentration, cmc for micelles and reverse cmc for reverse micelles. The reverse cmc values are smaller (0.204-0.293M) than the micellar cmc (0.4605-0.607M) was observed.1-butanol as a stabilizer provided information of the systems to give thermodynamically stable transparent w/o and o/w microemulsion due to its low linear thickness. Specific conductance, density and aggregation number had been used to characterize SDS and CTAB based microemulsions and the microemulsions prepared by non-ionic surfactant, tween 80 were characterized by only density measurement. Lower conductance and density are characteristics for w/o microemulsions having high 1-butanol content while in o/w microemulsions leads higher conductance and density. Steady-State Fluorescence Quenching method had been employed to determine the aggregation number, N of the organized self-assembled aggregates. The aggregation number of the aggregates in the microemulsions varied with composition of the microemulsions and depends only on the concentration of surfactant present in the systems. Aggregation number had been found to increase as the number of micellar aggregates increases. However, an increase in the number of reverse micellar aggregates in the system brought about gradual decrease of the aggregation number. As the quenching process of SDS based aggregates was very effective, however that of CTAB was less pronounced, the aggregation number of SDS based aggregates had been found to be comparatively lower than that of CTAB under similar experimental conditions. The results obtained show that N values which range 78–101 for SDS based aggregates and range 99-160 for CTAB based aggregates show a linear relationship with the concentration of surfactant. Detailed analysis of the conductivity, density and aggregation number, it can be tuned by changing composition of microemulsions and suitable compositions of microemulsions must be employed for the preparation of nanomaterials.