Controlled/“living” radical precipitation polymerization: A versatile polymerization technique for advanced functional polymers

As an emerging new polymerization technique, controlled/“living” radical precipitation polymerization (CRPP) involves the introduction of controlled/“living” radical polymerization (CRP) mechanism into the precipitation polymerization system and can be effectively implemented by simply replacing the initiator normally used in the traditional precipitation polymerization (e.g., azobisisobutyronitrile (AIBN)) with a CRP initiating system. It combines the advantages of the traditional precipitation polymerization and CRP and can thus be performed in a controlled manner without need for any surfactant and stabilizer, leading to the precise control over the sizes, compositions, surface functionalities, and “living” groups of the resulting polymer microspheres. Several CRPP approaches have been developed up to now, including atom transfer radical precipitation polymerization (ATRPP), iniferter-induced “living” radical precipitation polymerization (ILRPP), and reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization (RAFTPP). In this feature article, we provide a detailed overview of these recently developed CRPP approaches and demonstrate their high versatility in the design and synthesis of advanced functional polymers such as uniform, highly crosslinked, and “living” functional polymer microspheres and advanced molecularly imprinted polymers (MIPs) including MIP microspheres with improved binding properties, water-compatible MIP microspheres, and MIP microspheres with stimuli-responsive template binding properties in aqueous media. In addition, some perspectives on this new research area are also presented.