Effect of Chain Lengths of n-Alcohol on the Formation of Single-Phase Microemulsions in n-Heptane-Alcohol/Sodium Dodccyl Sulfate/Water Systems

摘要

To elucidate the clients of chain lengths of alcohols (1-butanol, l-hexanol, and 1-octanol) as cosurfactants on (hi' formation of a single-phase microcmulsion (L-rej>ion) in n-heptane-aleohol/sodiuni dodccyl sulfate (SDS)/water systems, the phase diagrams of pseudoternarv systems were determined under a fixed SDK/alcohol weight ratio (= 0,5). Conductivity, viscosity nml light scattering intensity of the n-region were measured sit 3℃, and the results discussed from the niicrostruclure of these systems. Using the SDH-free model system, the distribution of alcohol and the interfacial tension between oil (heptane) and water phases were measured in the presence of alcohol. Che dilferenee in distribution of alcohols resulting from differences in the chain lengths was found to be one of the key factors determining the extensions of (he region of microemulsion urn) the mierostructures. The L-regions in the hi'MUiol and octanol systems were much smaller than in the butanol system. The continuous phases of these systems were the oil-rich medium (water-in-oil-type) throughout the L-region with increasing the water content. The L-region in the bulanol system, on the other hand, was larger and (he continuous phases of this system changed gradually from the oil-rich to the water-rich medium (oil-in-walcr-type) through the bicontinuous medium (bicontimious-typc) wild increasing the water content.