Related Experiment Video
Updated: May 16, 2026
05:48
Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes
Published on: November 21, 2017
Ring-opening polymerization of L-lactide catalyzed by calcium complexes
1Department of Chemistry, National Chung Hsing University, Taichung 402, Taiwan, ROC.
Dalton Transactions (Cambridge, England : 2003)
|November 27, 2012
Summary
Novel calcium complexes efficiently catalyze L-lactide polymerization. These catalysts demonstrate excellent control and activity, even with high concentrations of benzyl alcohol transfer agents, offering a promising route for biodegradable polymer synthesis.
Area of Science:
- Organometallic Chemistry
- Polymer Chemistry
- Catalysis
Background:
- Calcium complexes are increasingly explored as catalysts for polymer synthesis.
- Ketiminate ligands offer tunable steric and electronic properties for metal complex stabilization.
Purpose of the Study:
- To synthesize and characterize novel NNO-tridentate ketiminate-supported calcium complexes.
- To evaluate the catalytic performance of these complexes in the ring-opening polymerization (ROP) of L-lactide.
Main Methods:
- Synthesis and characterization of calcium-ketiminate complexes.
- X-ray crystallography for structural determination.
- Ring-opening polymerization (ROP) studies of L-lactide using the synthesized catalysts.
- Kinetic analysis of the polymerization process.
Main Results:
- Successful synthesis and structural elucidation of mononuclear, hexa-coordinated calcium complexes.
- Rapid and well-controlled L-lactide polymerization catalyzed by the calcium complexes in the presence of alcohols.
- High catalytic activity observed even with 80 equivalents of benzyl alcohol as a transfer agent.
- Kinetic studies revealed first-order dependence on L-lactide and second-order dependence on benzyl alcohol.
Conclusions:
- NNO-tridentate ketiminate ligands effectively support calcium catalysts for L-lactide polymerization.
- The developed calcium complexes exhibit robust catalytic activity and control, suitable for producing biodegradable polymers.
- Understanding the reaction kinetics provides insights for optimizing polymerization conditions.
More Related Videos
11:42Synthesis of Monodisperse Cylindrical Nanoparticles via Crystallization-driven Self-assembly of Biodegradable Block Copolymers
Published on: June 20, 2019
11:17Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction
Published on: January 19, 2016
Related Concept Videos
00:57Cationic Chain-Growth Polymerization: Mechanism
The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the generated carbocation,...
01:17Ziegler–Natta Chain-Growth Polymerization: Overview
Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta catalyst, high molecular...
01:04Anionic Chain-Growth Polymerization: Mechanism
The mechanism for anionic chain-growth polymerization involves initiation, propagation, and termination steps. In the initiation step, a nucleophilic anion, such as butyl lithium, initiates the polymerization process by attacking the π bond of the vinylic monomer. As a result, a carbanion, stabilized by the electron‐withdrawing group, is generated. The resulting carbanion acts as a Michael donor in the propagation step and attacks the second vinylic monomer, which acts as a Michael acceptor.
01:16Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
01:25Production of Organic Acids
Lactic acid, an important organic acid extensively applied in food, pharmaceutical, and biodegradable polymer industries, is primarily produced via microbial fermentation. This method is favored over chemical synthesis due to its environmental sustainability and capacity for enantiomerically pure product formation. Among various microbial processes, the fermentation of starch-based substrates stands out due to the abundance and renewability of raw materials like corn and potatoes.Hydrolysis of...
02:24Acid-Catalyzed Ring-Opening of Epoxides
Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The...