Experimental Study on Dynamic Interfacial Tension with Mixture of SDS–PEG as Surfactants in a Coflowing Microfluidic Device

Abstract

In this work, a coflowing microfluidic device was used to determine the influence of different mixed sodium dodecyl sulfate (SDS)-poly(ethylene glycol) (PEG) compound systems on dynamic interfacial tension and, by extension, corresponding emulsion droplet sizes. The aqueous solutions were used as the continuous phase in the microfluidic device, while octane was used as the organic dispersed phase. Combined SDS-PEG systems lower the interfacial tension more than either component can alone up to the critical aggregation concentration (CAC) of SDS. Octane droplet sizes produced in the microfluidic device using combined SDS-PEG systems were smaller than those produced using SDS alone, and a reduction in dynamic interfacial tension as determined by drop size followed a pattern similar to that observed in the static case (PEG4000 > PEG600 > PEG400 > PEG200 > PEG8000) with the exception of PEG8000. Finally, a previously formulated model relating interfacial tension to droplet size was used to estimate the dynamic interfacial tensions in the microfluidic device.

Comparison of surfactant mass transfer with drop formation times from dynamic interfacial tension measurements in microchannels

“…DIT has been investigated mainly in T-junction microchannels [18,23] and co-flow microfluidic devices [24,25]. Flow focusing microfluidic devices are commonly used to produce droplets and exist in two configurations: hydrodynamic flow-focusing, where two liquid streams of the continuous phase surround the dispersed phase stream and break it to drops at the inlet [22,26] and geometrical focusing where the breakup of the dispersed phase happens at an orifice of size smaller than the main microchannel width [27,28].…”

Numerical Study of Surfactant Dynamics during Emulsification in a T-Junction Microchannel

“…Herein, the surfactant adsorption proceeds in two steps: (i) diffusion of the surfactant to the interface and (ii) adsorption and reorientation of the surfactant molecules (chemical kinetics). In microfluidics, dynamic interfacial tension phenomena are notoriously more complex , and have profound consequences on droplet volume, − pressure fluctuations, emulsion stability, − and interdroplet mass transfer . Droplet formation in microfluidic devices offers an especially interesting and rich playground to study surface phenomena .…”

Chemiluminescence as a Novel Indicator for Interactions of Surfactant–Polymer Mixtures at the Surface of Layered Double Hydroxides

“…In this case, the larger PEG molecules own lower hydrophilic character, decreasing the critical micelle concentration (CMC) of SDBS. 4 Accordingly, the content of SDBS absorbed at the surface of CO 3 -LDHs was decreased. In addition, Figure 5B shows that the CL intensity was increased with increasing PEG200 concentrations from 0.1 to 1% w/v and then remained constant up to 5% w/v, indicating the formation of the PEG@SDBS at the surface of CO 3 -LDHs.…”