Fact and Fancy about Lamellar Emulsions – A Closer Look Inside

Motivated by the hype about lamellar emulsions, we wanted to take a closer look at the microstructure of modern cosmetic emulsions stabilized by polyglycerol ester emulsifiers. Previously, we have developed a structure model of an emulsion stabilized by a polyglycerol ester emulsifier and consistency enhancers by using a number of highly specialized (e.g., scattering) methods. According to these results, the oil droplets are surrounded by several, irregularly spaced bilayers consisting of emulsifier and consistency enhancer. We now have extended this work to four alternative polyglycerol ester emulsifiers by using Cryo-TEM to study the microstructure of model emulsions. In none of the cases there was evidence for areas of stacked bilayers, i.e. a lamellar phase or multilamellar vesicles, which could be recognized by birefringence (e.g. Maltese crosses) in polarization microcopy if they were present. Such lamellar phases or multilamellar vesicles can be generated by overdosing the emulsifier, or could be a consequence of incomplete mixing. Therefore, polarization microcopy results can hardly be an indication for superior application performance and should not be confused with claim substantiation.