A new method for measuring the dynamic interfacial tension for flowing droplets of three-phase emulsion in the channel

Abstract

• We invent a method to measure dynamic interfacial tension of three-phase emulsion. • The real-time acquisition of dynamic interfacial tension in the channel is obtained. • The γ-t relationship shows the surfactant adsorption exist throughout the channel. • Ca - t images of various surfactant concentrations show different transfer mechanisms. In this work, we developed a method for measuring the dynamic interfacial tension of three-phase emulsion based on microfluidic devices. The interfacial tension of three-phase emulsion in the flow process changes rapidly and is difficult to measure, which has never been reported in the previous literature. Through the geometric analysis of the structure of three-phase emulsion, the MATLAB program is compiled to simulate the image. By combining the simulated images with the high-speed photographic images of the flowing droplet, the dynamic interfacial tension during the structural transformation of emulsion is derived. This method can obtain the interfacial tension of flowing droplets in microchannels in real time, especially for three-phase emulsion, and can calculate the instantaneous interfacial tension at an interval of 4 ms. The error range of the measured dynamic interfacial tension value is not more than 0.1 mN / m , which is relatively accurate. We also use the measured dynamic interfacial tension to draw the Ca - t image, which shows the obvious differences at high and low surfactant concentrations. This is due to the different mass transfer resistance of surfactants at high and low concentrations. In a short, this study helps us to further understand how surfactants diffuse during the flow process of three-phase emulsions, which further helps us to better regulate the emulsions.