Study on characteristics and functionality of mono/compound microdroplets generation of shear-thinning solutions in a flow-focusing microchannel

Xanthan gum as a versatile substance, finds application as a thickener, stabilizer, or suspending agent in a wide range of industries including the food industry, and pharmaceuticals. The research investigates the controllability, functionality, and size distribution of mono/compound droplets (Water/Oil/Water) formed from various solutions of xanthan gum (with different mass fractions of 0.1 wt%, 0.2 wt%, 0.3 wt%, and 0.4 wt%) as the dispersed phase in a selectively treated microchannel. An advanced selective surface treatment method with PloyvinylAlcohol (PVA) injection and plasma is done on the channel for the generation of compound droplets. The effect of concentrations of hydrophilic and lipophilic surfactants in oil and aqueous phases for stable droplet generation is studied and the generation diagram is represented. The analysis of multi-emulsions provided valuable insights into the various modes of breakup, the functional characteristics of the cores and shells, and the formation trends. The results revealed that by step-rising and decreasing the flow rate of the inner, middle, and outer phases, the number of the semi-size cores tripled, and the size of the inner core in single-core multiemulsion increased up to 38%.