Abstract:

The properties of jojoba oil make it uniquely suited as a raw material for the cosmetics industry. Water-based, thermodynamically stable prepns. of jojoba oil are essential in many formulations. New microemulsions were prepd. based on jojoba oil and different nonionic surfactants, namely polyoxyethylene-(ethylene oxide)10-oleyl alc. (brij 96V) and ethoxylated sorbitan esters (Tweens). The effects of the surfactants and of primary alcs. as cosurfactants on the isotropic regions of the phase diagram were elucidated. It was found that, up to a certain cosurfactant chain length, the isotropic region expanded considerably as chain length increased. The size of the isotropic region also increased as a function of the ethylene glycol content of the aq. phase in microemulsions based on ethoxylated alc. but shrank when ethylene glycol was included in microemulsions prepd. with ethoxylated sorbitan esters. Secondary structural phase transitions from water-in-oil to bicontinuous and to oil-in-water structures (as detd. by measuring cond. and viscosity) were found to be related to jojoba oil content. Dynamic light scattering and small angle X-ray scattering studies established that incorporation of jojoba oil into Brij 96V micelles caused micellar transformation from elongated to spherical droplets and a decrease in the aggregation no. [on SciFinder(R)]