Surface dilational rheological and foam properties of aromatic side chained N-acyltaurate amphiphiles

The surface dilational rheological behaviors of two anionic surfactants with aromatic group in branch, sodium N-2-(phenoxy)-tetradecanolytaurinate (12+B-T) and sodium N-2-(2-naphthoxy)-tetradecanolytaurinate (12+N-T), were expounded by oscillating bubble method and interfacial tension relaxation method. The foam properties of both surfactants were also investigated by air flowing method. The results show that the adsorption layers of both surfactants behave elastic in nature at low bulk concentration. With increasing concentration, the dilational modulus becomes more frequency dependent and reaches a maximum value. The diffusion-exchange process controls the dynamic dilational properties with increasing bulk concentration for 12+N-T, but not 12+B-T. The possible mechanism has been elucidated and confirmed by the high-frequency-limit value of surface dilational elasticity. The foam stability of 12+N-T is stronger than that of 12+B-T, which indicates that the low frequency elasticity plays a positive effect on foam stability for present systems.