Synthesis and properties of novel alkylbetaine zwitterionic gemini surfactants derived from cyanuric chloride

A series of novel alkylbetaine zwitterionic gemini surfactants (ZS Cn-2-Cn where n represents the hydrocarbon chain length of aliphatic amine, the values of n are 6, 8, 12, 14) were synthesized from cyanuric chloride, aliphatic amine, N,N-dimethylpropane-1,3-diamine and sodium chloroacetate. The chemical structures of the prepared compounds were confirmed by 1H NMR, 13C NMR, ESI-MS, IR spectra and elemental analysis. Their critical micelle concentrations (CMC) in the aqueous solutions were determined by surface-tension and steady-state fluorescence methods at 30 °C. A relationship between a logarithm of CMC and hydrophobic chain length showed a linear decrease upon increasing of chain length and then a departure from linearity at n = 12. The surface-tension measurements of ZS Cn-2-Cn determined that there is a low CMC, a great efficiency in lowering the surface tension. In addition, adsorption and micellization behavior of ZS Cn-2-Cn were estimated from pC20 and the minimum average area per surfactant molecule (Amin).