New Polyfunctional Biamphiphilic Surfactants Based on Alkylmethylmorpholinium Cation and Dodecyl Sulfate Anion

Abstract

New biamphiphilic surfactants (BSs) have been synthesized based on alkylmethylmorpholinium cation and dodecyl sulfate anion (Mor-n(DS), n = 4, 6, 8, 10). The structure of the biamphiphiles has been characterized by IR spectroscopy, ¹H NMR spectroscopy, mass spectrometry, and elemental analysis. The aggregation behavior of the biamphiphiles in aqueous solutions has been assessed by tensiometry, conductometry, fluorescence spectroscopy (using a pyrene probe) and dynamic and electrophoretic light scattering. It has been shown that an increase in the hydrophobic tail length by two carbon atoms in an amphiphilic cation leads to an increase in the surface activity of the surfactant by ~5 units and a decrease in the aggregation threshold of the systems by 1.5–2 times. It has been established that the formation of aggregates with hydrodynamic diameters of 20–120 nm depending on the alkyl chain length of the alkylmethylmorpholinium cation and BS concentration. The zeta potential of the systems ranges from –25 to –100 mV and decreases with increasing biamphiphile concentration. Spectrophotometry has been employed to show a significant solubilization capacity of the biamphiphiles with respect to a hydrophobic dye Orange OT. The compounds obtained may be of interest for biomedical applications and other high-tech areas.