Water-in-water emulsions are formed due to the thermodynamic incompatibility between their components, which leads to phase separation. Water-in-water emulsions have many advantages such as low cost, high quality, and sustainability. This review provides an overview of the formation and stabilization mechanisms of water-in-water emulsions. The stabilization of these emulsions and the factors influencing this process (e.g., particle type, particle concentration, particle charge, and aqueous two-phase concentration) are discussed. Different types of water-in-water emulsions are briefly described. In addition, a method for the structural design of water-in-water emulsions and related applications under various scenarios is presented. This review can serve as a research guide to aid in achieving a better understanding of the particle stabilization mechanisms of water-in-water emulsions.

水包水乳液是由于其组分之间的热力学不相容性而形成的，这会导致相分离。水包水乳液具有许多优点，例如低成本、高质量和可持续性。本综述概述了水包水乳液的形成和稳定机制。讨论了这些乳液的稳定性和影响该过程的因素（例如，颗粒类型、颗粒浓度、颗粒电荷和水性两相浓度）。简要描述了不同类型的水包水乳液。此外，还介绍了一种水包水乳液的结构设计方法和各种场景下的相关应用。