两仪聚合——拓扑结构聚合物合成新方法

Janus Polymerization:A Novel Approach towards Topology Design

两仪聚合(Janus polymerization)是在一条聚合增长链两端同时引发阳离子型和阴离子型开环聚合的聚合方法.两仪聚合可以一步从单体直接合成具有复杂拓扑结构的聚合物,包括两/多嵌段聚合物、超支化聚合物、杂臂星形聚合物和柱状聚合物刷等.本文总结了近年来本课题组有关两仪聚合方面的研究进展,介绍了两仪聚合特征与机理、两仪聚合在构筑拓扑结构聚合物上的应用、聚合产物独特而优异的性质、两仪聚合新体系等,并对两仪聚合发展作出了展望.

Janus polymerization combines cationic and anionic polymerizations at two ends of a single propagating chain involving a living/controlled chain-growth polymerization and a self-triggered stepwise polycondensation, which provides a facile way to synthesize novel polymers with sophisticated topologies in one step directly from monomers. Di-/Multi-block copolymers, branch polymers, mikto-arm star copolymers and cylindrical polymer brushes are synthesized using rare earth triflates catalysts assisted by various epoxy initiators owing to their specific position at the middle of the chain. This work reviews recent progress on Janus polymerization in our group. Specifically, the characteristic of rare earth metal catalysts and mechanism of Janus polymerization are discussed in detail where tripedal crows are employed to illustrate the mechanism. New methodologies for the construction of topological polymers are introduced, together with the unique and prominent properties, such as thermoplastic properties, self-assembly and self-healing behaviors and the corresponding applications in self-sealing films for plants and electrostatic spinning. A new Janus system is put forward which affords a facile synthetic method for functional polyesters by incorporating a modifiable monomer3,3-bis(chloromethyl)oxacyclobutane. Finally, the development of Janus polymerization including new catalytic systems and monomers is also prospected. The concept of Janus polymerization makes significant breakthroughs into traditional cognitions about incompatible cationic and anionic polymerization mechanisms in one system which motivates the power in the catalysis and synthesis of polymer chemistry.