Measurement of Critical Micelle Concentration (CMC) by Cyclic Voltammetry: CMCs for Sodium Dodecyl Sulfate Solution with Compounds Having Pyridine

Abstract

Electrochemical behavior of CMC in sodium dodecyl sulfate (SDS)-tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)3 ) solution is reported using a cyclic voltammetry (CV). Discussion of SDS-Ru(bpy)3 2+ solution is restricted to the regions slightly below and above the CMC. Kaifer and Bard suggested that detection of the CMC of SDS for methyl viologen is possible through the changes observed in the shape of cyclic voltammograms. This work was originated from doing experiment for enhancement of electrogenerated chemiluminescence intensity in the Ru(bpy)3 2+ solution with surfactants. Until recently, most applications of aqueous micelles were restricted to regions extending slightly below and above the CMC. Because, the interesting effects are being discovered at surfactant concentrations much below and above the critical point. Although various techniques of electrical conductance, turbidity, osmotic pressure, magnetic resonance, solubilization, light scattering intensity, surface tension, and fluorescence quenching to measure the CMC have been utilized, a determination of the CMC by the CV has been received little attention. And so, in this work the method of determining the CMC for compounds having pyridine is explained, and a variation of the microenvironments of SDSRu(bpy)3 2+ interactions in the vicinity of the CMC is discussed by using the model proposed by Brajter-Toth et al.