Effect of the Interfacial Tension on Droplet Association in Aqueous Multiphase Systems.

Aqueous multiphase systems (AMPS) were formed by mixtures of three or more incompatible water-soluble macromolecules. Droplets formed by different phases in the water-in-water emulsions were found to associate and their morphology was studied using confocal laser scanning microscopy. By analyzing the angles between different associated phases it was possible to determine the relative interfacial tensions between phases with respect to each other. In this manner, the relative interfacial tension of 15 different pairs of polymers solutions was determined. The effect of the total polymer concentration on the relative interfacial tensions was found to be small as long as mixing of the polymers in the phases was small. The effect of adding protein microgels was studied for systems where they adsorb at the interface between the phases. It is shown that protein microgels can in some cases stabilize associated droplets in suspension.