Synthesis, Characterization, Surface and Biological Activity of Diquaternary Cationic Surfactants Containing Ester Linkage

Two series of diquaternary cationic surfactants designated as E9Nm and E11Nm having two different alkyl chains in their chemical structure were synthesized. The chemical structures of these surfactants were confirmed using elemental analysis, FTIR and 1 H-NMR spectra. The surface activities of the different surfactants were determined using surface and interfacial tension at 25 °C. The surface parameters including: critical micelle concentration, effectiveness, efficiency, maximum surface excess and minimum surface area were determined. The surface activities of the cationic surfactants were correlated with their chemical structure. The surface activities of the surfactants increased with increasing the hydrophobic chain length. The adsorption and micellization tendencies of the surfactants in solution were determined using the free energies of adsorption and micellization. The synthesized surfactants were evaluated as biocides against bacteria and fungi. Biocidal activity data showed that a gradual increase in the hydrophobic chain length of the surfactant molecules gradually increases the efficiency of these surfactants as biocides.