Recent advances in RAFT-mediated surfactant-free emulsion polymerization

Advances in the understanding and application of reversible addition-fragmentation chain transfer (RAFT) polymerization in surfactant-free emulsion systems have been made over the last decade. RAFT-mediated surfactant-free emulsion polymerization not only serves as a powerful tool for preparing polymeric materials with controllable molecular weight, low polydispersity and high colloidal stability, but also can avoid the deleterious effects of small molecule surfactants. In this review, recent advances in RAFT-mediated surfactant-free emulsion polymerization are described in detail and classified according to several criteria: (i) various RAFT agents, including small RAFT agents, hydrophilic macro-RAFT agents and amphiphilic macro-RAFT agents; (ii) the different types of polymerization for the preparation of organic/inorganic hybrid materials, such as RAFT-mediated Pickering surfactant-free emulsion polymerization and RAFT-mediated surfactant-free encapsulating emulsion polymerization. At the same time, the current significance, outstanding challenges and issues, and the future directions of RAFT-mediated surfactant-free emulsion polymerization are also discussed.