Polarographic studies of non-ionic surfactants with reference to their structural influence on surface activity

The surface activity of a homologous series of non-ionic surfactants having 12-16 carbon atoms in the alkyl chain and different lengths of the polyoxyethylene (POE) group was studied by a direct current polarographic method. Polarographic micelle points (PMPs) were used to compare the surface activities of the non-ionic surfactants in dimethylformamide (DMF) media. Results obtained from this study showed that the PMP increased regularly as the percentage of DMF in the solutions increased, indicating a decrease in the surface activity. In DMF media, as in water, the surface activity of the non-ionic surfactants depends on the hydrophilic/lipophilic ratio. Either increasing the length of the alkyl chain or decreasing the length of the polyoxyethylene chain contributes both to an enhanced hydrophobicity and an increased surface activity of the non-ionic surfactants.