Interfacial tension oscillations without surfactant transfer.

The dynamic interfacial tension oscillations of different frequency and amplitude were observed by using a pendant drop method for tetraoctyl-, tetradodecyl-, tetrahexadecyl-, and tetraoctadecylammonium bromides at a nitrobenzene/water interface. Despite surfactant mass transfer from the nitrobenzene to the aqueous phase being negligible for these lipophilic derivatives, the oscillations were often accompanied by clouding of the organic phase in the vicinity of the interface. A possible mechanism of the observed phenomena is discussed in relation to spontaneous emulsification at the liquid-liquid interface.