Microemulsion Area Research Articles

Investigations into the formation and characterization of phospholipid microemulsions. II. Pseudo-ternary phase diagrams of systems containing water-lecithin-isopropyl myristate and alcohol: influence of purity of lecithin

The phase behaviour of quaternary systems composed of lecithin/isopropyi myristate/ water/and one of seven short-chain alcohols at various surfactant/cosurfactant mixing ratios ( K m ) has been investigated by the construction of phase diagrams. A commercially available soybean lecithin (namely, Epikuron 170, phosphatidylcholine purity 68–72%) was used in the study. Phase diagrams showed the area of existence of a stable isotropic region along the surfactant/oil axis (i.e., reverse microemulsion area; L 2) in all systems regardless of the K m . The existence of a second water-rich isotropic region (i.e., normal microemulsion area; l 1) was, however, seen to be very dependent upon the K m and occurred in only a few instances. This second isotropic region, L 1, always occurred in conjunction with a liquid crystalline domain, although in some cases, particularly at the lower K m , a liquid crystalline region was seen to occur without the presence of an L 1 phase. Comparison of the results with those obtained using higher purity lecithins (greater than 92% phosphatidylcholine content) indicated that while the phase diagrams were qualitatively similar, significant differences occurred at oil levels below 50%. It was found that the existence of an L 1 and LC region and the extent of the L 2 region were dependent upon both the purity of surfactant and the surfactant/cosurfactant mixing ratios ( K m ).

Phase diagrams of water and sodium dodecyl sulfate combined with four commercial nonionic surfactants

Phase diagrams in which water was combined with sodium dodecyl sulfate, plus one of four nonionic surfactants, as well as an aliphatic oil, were determined by visual observation and low‐angle X‐ray diffractometry. The results agreed with earlier investigations on specially synthesized polyethyleneglycol alkyl ether surfactants, except that the extended water‐in‐oil microemulsion areas were not found with the commercial surfactants.

POLYMERIZATION IN THE TRANSPARENT WATER-IN-OIL SOLUTIONS (I). METHYL METHACRYLATE AND THE COPOLYMERIZABLE COSURFACTANT

ABSTRACT Polymerization of methyl methacrylic acid (MMA) was made in transparent W/O microemulsions and solutions. Acrylic Acid (AA) and pentanol were used as cosurfactants and sodium dodecyl sulfate as surfactant Acrylic Acid as cosurfactant gave large microemulsion areas with the monomer of methyl methacrylic acid. Polymerization in areas where the microemulsion remained stable gave polymers with high molecular weights 106.