Microemulsions in Cosmetics and Detergency

Products for personal care and home care have to fulfill many different requirements regarding e.g. performance, esthetics, costs and safety. This has consequences for the use of new technologies such as microemulsions for this kind of applications. Although there have been numerous basic studies with microemulsions which show superiority in certain aspects of performance, broad applications of microemulsions in detergency and cosmetic products are not yet achieved. The reasons for this are manifold and depend on the specific application. From an economical point of view the high surfactant concentration is one aspect. The formation of microemulsions can be controlled by adjusting the temperature, the electrolyte content or the hydrophilic-lipophilic balance by varying the ratio of different surface active agents. All these techniques are applicable in cosmetics and detergency and have specific advantages and disadvantages. For example, most consumer products require a temperature stability which is usually not achieved with temperature-induced microemulsions. Therefore no general rule exists for the most suitable type of microemulsion but it depends on the application. Several examples are given which describe the status of different applications in cosmetics and detergency ranging from cleanser, bath oils, sunscreens, hair treatment to perfume and in-situ formation as well as the direct use of microemulsions.