Stabilization of carbon dioxide (CO2) bubbles in micrometer-diameter aqueous droplets and the formation of hollow microparticles

Abstract

We report an approach to stabilize carbon dioxide (CO₂) gas bubbles encapsulated in micrometer-diameter aqueous drops when water in the aqueous drops is evaporated. CO₂-in-water-in-oil double emulsion drops are generated using microfluidic approaches and evaporation is conducted in the presence of sodium dodecyl sulfate (SDS), poly(vinyl alcohol) (PVA) and/or graphene oxide (GO) particles dispersed in the aqueous phase of the double emulsion drops. We examine the roles of the bubble-to-drop size ratio, PVA and GO concentration in the stabilization of CO₂ bubbles upon water evaporation and show that thin-shell particles with encapsulated CO₂ bubbles can be obtained under optimized conditions. The developed approach offers a new strategy to study CO₂ dissolution and stability on the microscale and the synthesis of novel gas-core microparticles.