Microfluidic emulsification techniques for controllable emulsion production and functional microparticle synthesis

Emulsions play important roles in template synthesis of functional microparticles for myriad fields. The size, shape, composition and structure of emulsion droplets generally determine those features of the resultant microparticles and their functions. Precise control over these features of emulsions is vital to template synthesis of controllable application-oriented microparticles with advanced functions. This review summarizes recent progress on microfluidic emulsification techniques for controllable emulsion production and functional microparticle synthesis. First, versatile microfluidic emulsification techniques for controllable generation of emulsions from simple single emulsions to complex multiple emulsions are introduced. The flexible structural changes of emulsions induced by regulating the mesoscale structures of packed surfactant molecules at the interfaces are discussed. Then, rational synthesis of microparticles with controllable sizes, shapes, compositions, structures and functions from emulsion templates are introduced. The rational design of emulsion templates and interplay between the shape, structure and composition of microparticles to achieve desired functions for applications such as controlled release, water remediation, and catalysis are highlighted. Particularly, interplay between the mesoscale structures of functional components in the emulsion templates and the fine structures and advanced functions of certain microparticles, is discussed. Finally, future development of microfluidics in controllable emulsion production and microparticle synthesis is discussed.