Pyrimidinium cationic surfactants as emulsifiers for oil-in-water emulsions

Pyrimidinium cationic surfactants with 13–17 carbon atoms in the hydrophobe were used as emulsifiers for oil-inwater (heptane/water) emulsions at concentrations near the critical micelle concentrations. Interfacial tensions of the emulsifier solutions in water against heptane were measured. Drop size distributions of the emulsions were determined at different times using microscopic techniques, and the rate of coalescence was calculated. The structure having 16 carbon atoms in the alkyl chain had coalescence rates lower than the other structures, including two conventional C-16 cationics used as controls.