Phase Behavior and QLS (Quasielastic Light Scattering) in Potassium Linoleate/n-Alkanol Microemulsions

摘要

We present here pseudo-ternary phase maps on three surfactant stabilized quaternary systems composed of water, hexadecane, and potassium linoleate (KL) as surfactant and the three saturated primary alcohols, 1-butanol, 1-pentanol, and 1-hexanol as cosurfactants. These systems exhibit phase behavior analogous to that of the potassium oleate/n-alkanol systems recently reported. Butanol gives a system with one large single-phase region extending from the water side to the oil side of the diagram. Pentanol yields two areas of single phase, a large upper water in oil (w/o) region and a smaller finger-like oil in water (o/w) region arcing up from the water apex to ca 20% emulsifier. The hexanol system reveals the largest expanse of the w/o region, but in the water-continuous corner only a metastable clear area was encountered. Quasielastic Light Scattering (QLS) measurements are also reported in all three systems, and an attempt is made to correlate these measurements to the phase behavior. The butanol system gave no QLS evidence of aggregation at three different compositions. The pentanol and hexanol system gave diffusion coefficients that suggest the existence of aggregates with corrrelation lengths in the 100- to 700-A range. In general, diffusion coefficients for the hexanol system were smaller than those at comparable compositions in the pentanol system.