ON THE SPREADING OF AN INSOLUBLE SURFACTANT OVER A THIN VISCOUS-LIQUID LAYER

Reported here are results of a theoretical and experimental study of t he spreading of an insoluble surfactant over a thin liquid layer, Init ial concentrations of surfactant above and below CMC have been conside red. If the concentration is above CMC two distinct stages of spreadin g are found. (i) The first stage is the faster, and it is connected wi th micelle dissolution; (ii) the second stage is the slower, when the surfactant concentration falls below CMC. In the second stage, the for mation of a dry spot in the center of the film is observed. A similari ty solution of the corresponding equations for spreading gives good ag reement with experimental observations. (C) 1997 Academic Press.