Ring-opening copolymerization of cyclohexene oxide and maleic anhydride catalyzed by mononuclear [Zn(L)(H2O)] or binuclear [Zn2(L)(OAc)2(H2O)] complex based on the Salen-type Schiff-base ligand

Valence-variable Catalysts for Redox-controlled Switchable Ring-opening Polymerization

As a representative class of sustainable polymer materials, biodegradable polymers have attracted increasing interest in recent years. Despite significant advance of related polymerization techniques, realizing high sequence-control and easy-handling in ring-opening (co)polymerizations still remains a central challenge. To this end, a promising solution is the development of valence-variable metal-based catalysts for redox-induced switchable polymerization of cyclic esters, cyclic ethers, epoxides, and CO₂ . Through a valence-determined electron effect, the switch between different catalytically active states as well as dormant state contributes to convenient formation of polymer products with desired microstructures and various practical performances. This redox-controlled switchable strategy for controlled synthesis of polymers is overviewed in this Review with a focus on potential applications and challenges for further studies.

A trinuclear salen-Al complex for copolymerization of epoxides and anhydride: mechanistic insight into a cocatalyst-free system

A rare example of a trinuclear salen-Al complex is reported. Due to the intramolecular interaction, the trinuclear salen-Al complex can catalyze copolymerization with high activity in the absence of any cocatalyst. On the basis of a covalent coordination insertion mechanism, ABC(1)C(2) type tetrablock copolymers were produced using an hydroxyl initiator.

Copolymerization of epoxides with cyclic anhydrides catalyzed by dinuclear cobalt complexes

The alternating copolymerization of epoxides with cyclic anhydrides (CAs) is a highly diverse synthetic method for polyesters as the polymers’ architectures and properties can be easily controlled depending on the combination of two monomers. Thus, a variety of catalyst designs has been reported to prepare the desired copolymers efficiently. We herein report dinuclear cobalt–salen complexes with a benzene ring as a linker and their activities in copolymerization reactions. The dinuclear cobalt complexes showed a higher catalytic activity for the copolymerization of propylene oxide with phthalic anhydride than the corresponding mononuclear cobalt–salen complex and achieved one of the highest turnover frequencies ever reported. A variety of epoxides and CAs were also found to be copolymerized successfully by the dinuclear cobalt complex with a high catalytic activity.

Ring-Opening Copolymerization of Epoxides and Cyclic Anhydrides with Discrete Metal Complexes: Structure-Property Relationships

Polyesters synthesized through the alternating copolymerization of epoxides and cyclic anhydrides compose a growing class of polymers that exhibit an impressive array of chemical and physical properties. Because they are synthesized through the chain-growth polymerization of two variable monomers, their syntheses can be controlled by discrete metal complexes, and the resulting materials vary widely in their functionality and physical properties. This polymer-focused review gives a perspective on the current state of the field of epoxide/anhydride copolymerization mediated by discrete catalysts and the relationships between the structures and properties of these polyesters.

Ring-opening copolymerization (ROCOP): synthesis and properties of polyesters and polycarbonates

This feature article highlights the opportunities presented by ring-opening copolymerization (ROCOP) as a controlled route to prepare polyesters and polycarbonates.