Tailor-Made Polyelectrolyte Microcapsules: From Multilayers to Smart Containers

This review addresses the fabrication and properties of novel polyelectrolyte microcapsules, with an emphasis on their mechanical and permeability properties. Ease of preparation through layer‐by‐layer self assembly, accurate control over wall thickness as well as flexibility in the choice of constituents make these capsules very promising for numerous applications in materials and life science. Moreover, by engineering the inner and outer interfaces, these capsules can be used as microreactors for precipitation, crystallization, and polymerization reactions, as well as enzymatic, and heterogeneous catalysis. Wrap artists: Hollow polyelectrolyte microcapsules have promising perspectives in numerous applications, such as engineering, biotechnology, and medicine. In this Review, the recent advances in this field are presented, with a focus on the permeability properties of the capsules as well as on their application as microreactors. The picture shows a library of 15 dye‐modified capsules of poly(allylamine)/poly(styrene sulfonate).