Development of a versatile microencapsulation technique for aqueous phases using inverse emulsion

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The development of microencapsulation techniques that can microencapsulate a wide variety of aqueous phases with different functions can greatly promote the advancement of microcapsule-based functional materials. Herein, a novel microencapsulation technique to microencapsulate aqueous phases with different functions was successfully established based on the inverse emulsion. Using pure water as the targeting core, the shell formation mechanism was carefully studied for this microencapsulation technique. Different cross-linkers, including glycerol, poly(vinyl alcohol) (PVA), and polyethyleneimine (PEI) with multiple reactive hydrogen atoms, were adopted to adjust the microcapsule quality. It finds that the microcapsules have relatively low quality when no cross-linker was used, and that they became robust when cross-linked agents were adopted. Importantly, the higher the functionality of the cross-linker, the better the impermeability of the microcapsules shell to retain the core content. This technique was applied to microencapsulate common compounds of different nature in the laboratory, including water-soluble organics, water-soluble inorganics, and water-based dispersions, to demonstrate its versatility. It shows that the technique can microencapsulate a wide variety of water-soluble/dispersible substances except for the inorganic strong acid. The established technique opens a window to fabricate high-quality microcapsules containing aqueous phases with diversified functions, promoting the development of microcapsule-based functional materials.