DYNAMIC SURFACE-PROPERTIES OF SOLUTIONS OF PHOSPHINE OXIDES - A CAPILLARY WAVE STUDY

The characteristics of capillary waves on the surface of aqueous solut ions of dimethylalkyl phosphine oxides have been measured as a functio n of frequency and surfactant concentration. The damping coefficient f or solutions of dodecyldimethyl phosphine oxide increased with concent ration, passed through a local maximum below the CMC, and was independ ent of concentration above the CMC. For solutions of decyldimethyl pho sphine oxide, a second maximum is observed at the CMC and the damping decreases considerably in the micellar region. This effect can be expl ained by an influence of the micellization kinetics on the dynamic sur face elasticity and was not observed earlier for solutions of nonionic surfactants. The results are used to calculate the characteristic tim e of the slow step of the micellization process. (C) 1997 Academic Pre ss.