From controlled radical polymerization of vinyl ether to polymerization-induced self-assembly

Vinyl ether (VE) was long believed to be among the monomers that could not be radically homopolymerized. Therefore, to synthesize block copolymers with versatile radically polymerizable monomers, efficient transformation reactions were necessary between living cationic and controlled radical polymerizations. Under such circumstances, some groundbreaking polymerizations have been discovered. One reaction, a metal-free RAFT cationic polymerization, enabled the in situ introduction of the thiocarbonylthio moiety into poly(VE)s. This technique produced block copolymers using both cationic and radical RAFT processes. Advances in research have made it possible to perform radical homopolymerization with hydroxy-functional VE. This achievement was attributed to the hydrogen bonding between the VE oxygen and the hydroxy group that reduced the reactivity of the growing radical. Consequently, RAFT radical polymerization of VE was achieved due to hydrogen bonds and/or cation-pi interactions between VE monomers and the propagating radical. Thus, vinyl ether became a radically polymerizable monomer. By using the resulting poly(VE) as a thermoresponsive polymer and as a reactive emulsifier for polymerization-induced self-assembly, various functional polymers and nano-objects can be obtained. This review focuses on the controlled radical polymerization of VEs and the related self-assemblies.