Slow road to stability for emulsions
By studying the behavior of tiny particles at an interface between oil and water, researchers at Harvard have discovered that stabilized emulsions may take longer to reach equilibrium than previously thought. Much longer, in fact. “We were looking at what we thought would be a very simple phenomenon, and we found something very strange,” said principal investigator Vinothan Manoharan, associate professor of chemical engineering and physics at the Harvard School of Engineering and Applied Sciences (SEAS). “We knew that the particle would stick to the interface, and other researchers had assumed this event happened instantaneously,” he says. “We actually found that the timescale for this process was months to years.” The findings, published in Nature Materials on Dec. 4, have important implications for manufacturing processes used in pharmaceuticals, cosmetics, and foods. An emulsion is a mixture of two or more insoluble liquids — usually oil and water. A simple emulsion such as vinaigrette takes energy...