Can oil and water mix?

© 2021 EPFL - Common experience tells us that oil and water do not mix. Yet, it turns out that they can mix when oil is dispersed as small droplets in water. This strange behavior has long vexed scientists because there is no explanation for it. A team of EPFL and ICTP scientists have studied this question using novel optical technology and discovered the mechanism by which these two neutral and immiscible compounds can in fact mix together and form emulsions. The answer lies in the electrical charge distribution at the interface. For more than hundred years, chemists have wondered about this question: How can tiny oil droplets exist in water without any stabilizing molecules? -After all, water molecules have such strong and favored interactions with one another that they do not like to incorporate molecules that do not participate in these interactions.-, says Prof. Sylvie Roke, the lead investigator of the study. Indeed, oil and water segregate from one another when simply mixed.