Encapsulation of Liquids via Polymer Precipitation in Emulsions

Microencapsulation strategies enable the confinement of sensitive active materials in a protective shell, giving capsules with applications across pharmaceuticals, foodstuffs, agriculture, textiles, cosmetics, and energy storage. Among the different approaches, the soft template encapsulation method is a widely used technique that leverages emulsions as templates and forms spherical microcapsules with a liquid core and polymeric shell. Within the emulsion template umbrella, interfacial polymerization, phase internal phase separation, and polymer precipitation can all be used. The main limitation of interfacial polymerization is that the core will inevitably contain impurities such as residual monomers, which can affect the performance of the encapsulated material. This is especially relevant when performance efficiency strongly depends on its pristine composition. In this perspective, we focus on polymer precipitation soft-template strategies for capsule formation, and the complementarity of this approach to the more widely used interfacial polymerization. Polymer precipitation strategies enable the encapsulation of sensitive cores (or payloads) and can include those that are viscous, hygroscopic, and reactive.