Hydrophile-Lipophile-Balance of Ionic Surfactants Containing Two Long-chain Alkyl Groups

Abstract

Phase diagrams for three component systems, (Cl81-137)2N (CHs), Cl- (DOAC)-1-decanol water and DOAC8Fig7N+ (CH, ), Cl--water at 50°C have been studied. In the former system, there were reversed mesomorphous phases and reversed micellar solution phases, while there were normal mesomorphous phases and normal micellar solution phases in the latter. A lamellar liquid crystalline phase can be formed in a very wide range of concentration (---3.7wt%--7-130wt%) in DOAC-water system. By comparing these results with the phase diagrams of ordiiiary i9ni-c surfactant-long-chain alcohol-water systems, it is suggested that ionic surfactants. contai: ng twosong-chain alkyl groups like DOAC have optimum hydrophile-lipophilebalancl (Fad, ) and that t "the dissolution mechanism of these compounds in water is similar to that 4 certaifi inixtur4s of an ordinary ionic surfactant and an alcohol. HLBs of Aerosol OT and q, 21-125, *(CH₃), 1- are nearly optimum and slightly more hydrophilic than DOAC, and the miqellar solution phases exist in a narrow range of concentration: in these surfactants and water kstems. HLBs of these surfactants seem to change in a iOn of high concentration or in the preSence of an oil.