Studies On The Properties Of Organized Assemblies In Mixtures Of CTAB/SDS Surfactants System By Cyclic Voltammetry

In this article the mixture of cationic and anionic surfactant system, which has an important potentiality in the application field, was investigated thoroughly and systematically by cyclic voltammetry for the first time. The characterization method of organized assembles with diffusion coefficient was discussed. The change law of structures and properties in organized assembles were also revealed.Cyclic voltammetry measurement in the mixture of cationic surfactant (CTAB:cetyl trimethyl ammonium bromide) and anionic surfactant (SDS:sodium dodecyl sulfate) was proved that ferrocene was performed as an ideal electroactive probe in order to detect electronic properties of mixed surfactant system. Electrochemical reaction of ferrocene was a diffusion-controlled electron reversible process in this system, and Randels-Sevick equation was adopted to calculate the diffusion coefficient. As an important parameter of organized assembles, diffusion coefficient was related with the structure and character of organized assembles. The transformation of organized assembles and the diffusion method of ferrocene were concluded expediently and effectively by the change of diffusion coefficient curve, which offered a new way in controlling microstructure study of organized assembles.The study found that some factors like surfactant concentration, salt, temperature and so on can also influence diffusion coefficient of organized assembles. The Aggregation numbers and volume added with the increasing of concentration, resulting in the decrease of diffusion coefficient. Salt influenced the diffusion coefficient of organized assembles mainly by counter-ions. When the counter-ions were the same, the size and hydrability of co-ions also had effects on diffusion coefficient. The increasing energy of organized assembles induced the increasement in diffusion coefficients when temperature of the system was elevated. Furthermore, in this system liquid crystal with colorful polarizing was discovered and discussed tentatively.The experimental results also indicated that aqueous two-phase system (abbreviated as ATPS) possessed reversibility in dynamics and temperature in this system. When the ratio of top vulume to bottom volume was close to 1, the ATPS forming time was short, and the variation trend of diffusion coefficient curve was slow. However, when the ratio of top vulume to bottom volume deviated from 1, the conclusions were opposite. Salt remarkably shortened the forming time of ATPS, but different kinds of salt could change the width and position of ATPS.With much theoretical value and application potential, organized assembles in this study were not only mensurated by cyclic voltammetry, but also explained effectively on the mechanism, which offered a new way in quickly mensurating structure and character of organized assembles.