Aggregation properties of cationic gemini surfactants in aqueous solution
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Wrocław University of Technology
Publication date: 2002-01-01
Physicochem. Probl. Miner. Process. 2002;36(1):51–64
New cationic gemini surfactants bearing two hydrogen methanesulphonate groups and two long- chain alkyl groups (octyl, dodecyl or hexadecyl) were prepared in good yields by the reaction of N,N’-bis-alkyl,N,N’-bis(3-aminopropyl)ethylenediamine with methanesulphonic acid. All of these gemini salts showed good water solubility. Their aggregation ability in water has been determined by steady-state fluorescence spectroscopy. Furthermore, the micellar properties for the concentration near above the cmc have been characterized by the aggregation number, Nagg. The presence of the dimeric segments in the surfactant molecule is found to be in charge of their unusual physicochemical behavior. They are very efficient at adsorbing at the free surface and at forming micelles in water. Accordingly, both the micelle-forming property, and the ability to lower the surface tension increased with the increase in the length of the hydrophobic chain. The studied surfactants were found to form stable and reproducible n-tetradecane emulsions, for which the multimodal size distribution, effective diameter and zeta potential in the system: n-tetradecane/water/surfactant IVa-c have been determined.