Enolic Schiff Base Zinc Amide Complexes: Highly Active Catalysts for Ring-Opening Polymerization of Lactide and ε-Caprolactone

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.

Recent progress in nanocomposites of carbon dioxide fixation derived reproducible biomedical polymers

In recent years, the environmental problems accompanying the extensive application of biomedical polymer materials produced from fossil fuels have attracted more and more attentions. As many biomedical polymer products are disposable, their life cycle is relatively short. Most of the used or overdue biomedical polymer products need to be burned after destruction, which increases the emission of carbon dioxide (CO₂). Developing biomedical products based on CO₂ fixation derived polymers with reproducible sources, and gradually replacing their unsustainable fossil-based counterparts, will promote the recycling of CO₂ in this field and do good to control the greenhouse effect. Unfortunately, most of the existing polymer materials from renewable raw materials have some property shortages, which make them unable to meet the gradually improved quality and property requirements of biomedical products. In order to overcome these shortages, much time and effort has been dedicated to applying nanotechnology in this field. The present paper reviews recent advances in nanocomposites of CO₂ fixation derived reproducible polymers for biomedical applications, and several promising strategies for further research directions in this field are highlighted.

Zinc 8-aminotrihydroquinolines appended with pendant N-diphenylphosphinoethyl arms as exceptionally active catalysts for the ROP of ε-CL

Through activation with LiCH2SiMe3 or LiN(SiMe3)2, zinc(ii) chloride complexes bearing 5,6,7-trihydroquinolin-8-amines appended with pendant diphenyl phosphine units displayed remarkable catalytic activity for ROP of ε-caprolactone.

Monomer Controlled Switchable Copolymerization: A Feasible Route for the Functionalization of Poly(lactide)

Switchable polymerization is an attractive strategy to enable the sequential selectivity of multi-block polyesters. Besides, these well-defined multi-block polyesters could enable further modification for wider applications. Herein, based on the reversible insertion of CO₂ by Salen-Mn^III , a new monomer controlled self-switchable polymerization route was developed. Chemoselective ring opening copolymerization of O-carboxyanhydrides (OCAs) and lactide (LA) was explored without cocatalyst. The sequential conversion of OCAs and LA into the polymer chain could form multi-block polyesters. Based on this strategy, a series of multi-block polyesters with different pendant groups were synthesized. Furthermore, by modifying the propargyl-containing copolymers with quaternary ammonium groups, we have realized antibacterial functionalization of PLA. These results imply the potential application of this strategy for the fabrication of functional polymers for biomedical applications.

Copolymerization of lactide, epoxides and carbon dioxide: a highly efficient heterogeneous ternary catalyst system

The controlled copolymerization of mixed monomers that usually imparts distinct advantages into single polymer chains and requires a single versatile catalyst remains a key challenge in polymer chemistry.

Efficient ternary catalyst system for the copolymerization of lactide, epoxides and CO2: new insights into the cooperative mechanism

Ternary catalyst systems (TCSs) are an emerging type of catalyst for the synthesis of multiblock copolymers of lactide (LA), epoxides and CO₂.