A spontaneous phase separation method driven by interfacial tension: The preparation of aqueous two-phase emulsions in microchannel

• Published in: Separation and purification technology Vol. 373; p. 133618
• Main Authors: Xu, Xue, Yi, Haozhe, Fu, Taotao, Ma, Daofan, Zhu, Chunying, Ma, Youguang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 18.11.2025
• Subjects: Aqueous two-phase system; Droplet migration; Interfacial tension; Microchannel; Phase separation; Droplet migration; Microchannel; Phase separation; Interfacial tension; Aqueous two-phase system
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2025.133618

•A phase separation method driven by interfacial tension is proposed.•Aqueous two-phase emulsions are prepared by introducing an inert ionic liquid.•An increase in γPF6-TSC facilitates the spontaneous phase separation of droplets.•A prediction model for critical conditions of droplet migration is developed.•The entrainment of the ionic liquid could be suppressed by controlling LTSC*<1.4. The conventional shearing methods for the preparation of emulsions with extremely low interfacial tension usually bring about suboptimal uniformity due to the unstable rupture of the droplet neck. For instance, although the aqueous two-phase systems are widely used in biomedicine, pharmacy, and separation enrichment, the extremely low interfacial tension arises a challenge to the generation of aqueous two-phase emulsions using conventional microfluidic devices. In this study, a novel spontaneous phase separation method driven by interfacial tension is proposed to achieve the stable generation of polyethylene glycol/trisodium citrate aqueous two-phase emulsion and polyethylene glycol/dextran aqueous two-phase emulsion in the microchannel. A predictive model for the critical condition of droplet migration is proposed and validated. This study provides a useful reference for the preparation of aqueous two-phase emulsions.