One-step preparation of hydrophilic-hydrophobic asymmetric bilayer microcapsules via photopolymerization

Microcapsules with large cavities have been widely used as microcontainers in various fields. Their practical applications in aqueous systems often require a combination of water dispersibility, water-resistance and mechanical properties. Microcapsule architectures combining all these characteristics face challenges including delicate structure design and efficient fabrication. In this work, a novel kind of hydrophilic-hydrophobic asymmetric bilayer microcapsule was developed, which achieved a good combination of the desired features for application in aqueous systems. The bilayer microcapsules with a hydrophilic outer shell and a hydrophobic inner shell were prepared in one step by "phase separation inside an emulsion droplet" combined with photopolymerization. With this unique hydrophilic-hydrophobic asymmetric shell, the microcapsules possessed balanced dispersibility in water and water-resistance properties as well as simultaneously exhibiting outstanding mechanical properties.