Characterization of aqueous microemulsions by phase diagrams and interfacetension measurements

The phase diagrams of ternary systems water/n-undecane/alkylpolyglycol ethe r and quaternary; systems water/n-undecane/alkylpolyglycol ether/cosurfacta nt were established In our investigations commercial grade alkylpolyglycol ether mixtures (Marlipal) and the hydrocarbon n-undecane (Halpaclean UN. <9 5% n-undecane) were used. The phase diagrams of these these systems were de termined in dependence on the ethoxylation number j of the alkyl-polyglycol ether CiEj and the cosurfactants. In the pseudo-binary concentration/temperature diagram (ratio of water (c(W )) to oil (c(O)). c(W)/c(O) = 1), 1-, 2-, and 3-phase regions were observed . The positions of the 3-phase regions in the phase diagrams are dependend on the ethoxylation number of the alkylpolyglycol ethers. The addition of c osurfactants as n-pentanol, i-pentanol, 2-methyl-1-pentanol to the above me ntioned ternary; systems results in the phase diagrams in a shift of the 3- phase regions to lower temperatures. The interfacial tensions (gamma) of the separated two and three phase syste ms were measured using the spinning drop method. The outstanding detergency of microemulsions is connected with the ultra-low interfacial tension of a bout gamma similar to 10(-3) mN m(-1) particularly against the oil phase.