Measurement of dynamic surface tension to determine critical micellar concentration in lipophilic silicons surfactants

Silicone surfactants are becoming increasingly important in the pharmaceuti cal and cosmetic industry, because of their versatility, low cost, and tech nological advantages. The present study was designed to measure the critica l micellar concentration of three non-ionic silicone surfactants. one water -soluble and two lipid-soluble. We measured surface tension with a techniqu e based on drop geometry. Solubility and dispersibility in water were teste d in the two lipophilic surfactants with visible and UV light spectrophotom etry. The data obtained with all techniques showed a characteristic behavio r of lipophilic silicone surfactants, which did not entirely conform to the definition of critical micellar concentration. (C) 2000 Published by Elsev ier Science S.A. All rights reserved.