Synthesis, Characterization and Solution Properties of Novel Cationic Ester-Based Gemini Surfactants

The present investigation involves the synthesis of a series of novel green ethylene oxide-linked diester-functionalized cationic gemini surfactants 2,2'-[(oxybis(ethane-1,2-diyl))bis(oxy)]bis(N-alkyl-N,N-dimethyl-2-oxo-ethanaminium) dichloride (C-m-DEG-C-m; m = 12, 14, 16). These compounds were characterized by H-1-NMR, MS-ESI (+), FT-IR spectroscopy and elemental analysis; their solution properties were evaluated by surface tension and rheology measurements. The dimeric surfactant, C-m-DEG-C-m, possesses improved physicochemical properties as compared to its monomeric counterpart. Much lower critical micelle concentration (cmc) makes the cationic gemini surfactants more useful for the biomedical, pharmaceutical, industrial and academic sectors. Longer the alkyl chain of surfactants lower are the cmc values, the order is C-16-DEG-C-16 < C-14-DEG-C-14 < C-12-DEG-C-12. For all the three synthesized gemini surfactants no cloud point was noticed in between the temperatures 0 degrees C to 100 degrees C at the concentrations 0.002 mM, 0.02 mM and 0.2 mM of the aqueous surfactant solutions which is a beneficial factor for the use of these amphiphiles in various areas of application.