Microfluidic fabrication of polymersomes enclosing an active Belousov-Zhabotinsky (BZ) reaction: Effect on their stability of solute concentrations in the external media

Core/shell double emulsions were fabricated using glasscapillary based microfluidic techniques. Poly(butadiene) 46-bpoly(ethylene oxide)30 in mixture with cyclo-hexane/chloroform were contained as the shell part of droplets, whose core part was the full 1,4-cyclohexadiene based Belousov-Zhabotinsky reaction solution of unknown osmolality. The droplets were collected in solutions of both low and relatively high concentrations of salt. This resulted in the respective increase or decrease of the core part diameter. In both cases, after an incubation period, the droplets eventually evolved into polymer vesicles. In solutions with low concentration of salt, the droplets evolved into polymer vesicles after the evaporation of the vola-tile solvent contained in the shell part. Due to the dewetting of the shell and core parts, droplets in solutions of relatively high salt concentration evolved into polymer vesicles only after three days of incubation. The dewetted shell part displayed crescent-moon-shapes with different curvatures. The final diameter of the vesicles differed from the diameter of the initial core droplets. We demonstrate that vesicles with unknown osmolality core parts are formed in both solutions of very low or relatively high concentration of salt; furthermore, we also demonstrate that they follow different formation pathways. In the appropriate conditions, the vesicles experienced a form of "collapsing" behavior due to the activity of the entrapped chemical reaction. Published by Elsevier B.V.