POLAROGRAPHIC STUDIES OF NONIONIC SURFACTANTS WITH REFERENCE TO THEIRSTRUCTURAL INFLUENCE ON SURFACE-ACTIVITY

The surface activity of a homologous series of non-ionic surfactants h aving 12-16 carbon atoms in the alkyl chain and different lengths of t he polyoxyethylene (POE) group was studied by a direct current polarog raphic method. Polarographic micelle points (PMPs) were used to compar e the surface activities of the non-ionic surfactants in dimethylforma mide (DMF) media. Results obtained from this study showed that the PMP increased regularly as the percentage of DMF in the solutions increas ed, indicating a decrease in the surface activity. In DMF media, as in water, the surface activity of the non-ionic surfactants depends on t he hydrophilic/lipophilic ratio. Either increasing the length of the a lkyl chain or decreasing the length of the polyoxyethylene chain contr ibutes both to an enhanced hydrophobicity and an increased surface act ivity of the non-ionic surfactants.