Synthesis and Surface Properties Study of a Series of Cationic Surfactants with Different Hydrophobic Chain Lengths

摘要

A series of three cationic surfactants with different chain lengths, i.e. O-decyl-, O-dodecyl- and O-tetradecyl-N,N'-diisopropylisourea hydrochloride were synthesized. The chemical structures of the prepared compounds were confirmed using chemical analysis, Fourier transform infra red spectroscopy and nuclear magnetic resonance spectra and chromatography coupled with mass spectrometry. Several surface properties of the synthesized surfactants were studied in aqueous solution. Surface tension, conductivity and the foaming power were measured and the critical micelle concentration (CMC) was determined at 25 ℃. These results were correlated to the surfactant chemical structure. The surfactant that provided the best surface activity was the O-dodecyl-N,N'-diisopropyiisourea hydrochloride. The CMC was found to be significantly dependent on the hydrophobic chain length and decreased with increasing of the carbon number in the alkyl chain. The surfactants synthesized have an interesting foaming power. The surfactant with the longest alkyl chain exhibited the highest foamability.