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

Silicone surfactants are becoming increasingly important in the pharmaceutical and cosmetic industry, because of their versatility, low cost, and technological advantages. The present study was designed to measure the critical micellar concentration of three non-ionic silicone surfactants, one water-soluble and two lipid-soluble. We measured surface tension with a technique based on drop geometry. Solubility and dispersibility in water were tested in the two lipophilic surfactants with visible and UV light spectrophotometry. The data obtained with all techniques showed a characteristic behavior of lipophilic silicone surfactants, which did not entirely conform to the definition of critical micellar concentration.