Synthesis and Physicochemical Properties of Novel Phenyl-Containing Sulfobetaine Surfactants

A novel series of sulfobetaine surfactants, 3-((4-(alkoxy)-3,5-dimethylbenzyl) dimethylammonio)-2-hydroxy-propane-1-sulfonate (CnOBSb, n = 12, 14, and 16), were synthesized for the first time. The chemical structures of products were characterized by high-resolution mass spectra, H-1 NMR, and C-13 NMR spectrometry. The physicochemical properties of CnOBSb were studied by thermogravimetric analysis, equilibrium surface tension measurement, steady-state fluorescence, dynamic light scattering (DLS), and cryogenic transmission electron microscopy (cryo-TEM). The results demonstrated that surface tension values of CnOBSb are in the range of 28.32-30.14 mN/m at a fairly low critical micelle concentration (cmc). The adsorption and micellization properties of CnOBSb were dependent on the hydrocarbon chain length and presence of phenyl group. The results of DLS and cryo-TEM measurements revealed that CnOBSb molecules spontaneously formed vesicles in aqueous solution above the cmc. Furthermore, the application properties indicated that CnOBSb possessed superior interfacial tension capability, outstanding wetting ability, and good foaming and emulsifying properties.