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Two types of micelle formation in organic solvents

1969; Elsevier BV; Volume: 29; Issue: 1 Linguagem: Inglês

10.1016/0021-9797(69)90341-5

1095-7103

Per Ekwall,

Advanced Polymer Synthesis and Characterization

In ternary systems of ionic association colloids—for instance, an alkali soap, water, and a liquid fatty acid or alcohol—two regions of homogeneous isotropic solution occur, namely, a region L1 of ordinary aqueous solution and a region L2 in which the added amphiphilic substance is the solvent. Both have micellar structure: the micelles in L1 are of the usual type with a hydrocarbon core; those in L2 are of a “reversed” type with a water core, surrounded by amphiphile molecules, oriented with the hydrophilic groups facing the water and the hydrocarbon chains outwards. The micelles are formed in different ways in L2 solutions of the fatty acid and alcohol systems. In the former a molecular compound of soap and fatty acid forms even in the water-free state; the acid soap binds water and in hydrated form gives rise to micelles of the “reversed” type, dissolved in fatty acid. In the water-free alcohol-soap system no corresponding molecular compound is formed; the L2 solutions require a certain minimum amount of water for their existence and aggregates between alcohol and soap form only through the agency of water. They give rise to micelles of the “reversed” type, dissolved in alcohol.