Recent developments in main group metal complexes catalyzed/initiated polymerization of lactides and related cyclic esters

Wu, Jincai; Yu, Te-Liang; Chen, Chi‐Tien; Lin, Chu‐Chieh

doi:10.1016/j.ccr.2005.07.010

Cited by 747 publications

(105 citation statements)

References 62 publications

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“…Metal alkoxide species, M-OR, have been shown to be the true active species in numerous ROP processes. [1][2][3][4][5][6][7][8][9][10][11][12][13][18][19][20][21][22][23][24] For example, in 2004, Lewiński and co-workers reported the first structurally characterized aluminum ε-caprolactone complex, indicating that the Al-Me group has poor reactivity with CL. 77 Thus, in most ROP cases, an alcohol is used as an initiator and is essential in order to start the polymerization.…”

Section: Introductionmentioning

confidence: 99%

A Comparison of Gallium and Indium Alkoxide Complexes as Catalysts for Ring-Opening Polymerization of Lactide

et al. 2017

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ABSTRACT:The synthesis, characterization, and reactivity of an aluminum alkoxide complex supported by a ferrocene-based ligand, (thiolfan*)Al(O t Bu) (1 red , thiolfan* = 1,1'-di(2,4-di-tert-butyl-6-thiophenoxy)ferrocene), are reported. The homopolymers of L-lactide (LA), ε-caprolactone (CL), δ-valerolactone (VL), cyclohexene oxide (CHO), trimethylene carbonate (TMC), and their copolymers were obtained in a controlled manner by using redox reagents. Detailed DFT calculations and experimental studies were performed to investigate the mechanism. Mechanistic studies show that after the insertion of the first monomer, the coordination effect of the carbonyl group, which has usually been ignored in previous reports, can significantly change the energy barrier of the propagation steps, thus playing an important role in polymerization and copolymerization processes.

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Section: Introductionmentioning

confidence: 99%

A Comparison of Gallium and Indium Alkoxide Complexes as Catalysts for Ring-Opening Polymerization of Lactide

et al. 2017

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“…Among the metal-based catalysts, rare-earth metal complexes show excellent performance for the ROP of lactides, due to their qualities such as living behaviours, controlled molar weights, and very narrow molar weight distributions [13][14][15][16]. Many different lithium complexes have been identified as excellent catalysts for the ROP of lactides in alcohol [17]. Particularly, divalent metal catalysts bearing a monoanionic auxiliary skeleton are advantageous due to their low cost, and group 3 metal complexes are also exquisite initiators in the synthesis of PLAs by the ROP of rac-lactide [18,19].…”

Section: Introductionmentioning

confidence: 99%

Computational Studies on the Selective Polymerization of Lactide Catalyzed by Bifunctional Yttrium NHC Catalyst

et al. 2017

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Abstract:A theoretical investigation of the ring-opening polymerization (ROP) mechanism of rac-lactide (LA) with an yttrium complex featuring a N-heterocyclic carbine (NHC) tethered moiety is reported. It was found that the carbonyl of lactide is attacked by N(SiMe 3 ) 2 group rather than NHC species at the chain initiation step. The polymerization selectivity was further investigated via two consecutive insertions of lactide monomer molecules. The insertion of the second monomer in different assembly modes indicated that the steric interactions between the last enchained monomer unit and the incoming monomer together with the repulsion between the incoming monomer and the ligand framework are the primary factors determining the stereoselectivity. The interaction energy between the monomer and the metal center could also play an important role in the stereocontrol.

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“…After the discovery of the stereoselective polymerization of racemic lactides by chiral binaphthyl Schiff base aluminum complex [21], a large synthetic effort has been devoted to the preparation of five-coordinate SALEN aluminum complexes and their use in the ROP of lactones and lactides. The relationship between structure of the catalytic complexes and stereoselectivity of the polymerization has been investigated and elucidated [6][7][8][9][10]22]. Recent organometallic literature has featured reports of many alkylaluminum compounds bearing bidentate N,N-, N,S-, or N,O-donor ligands [23][24][25][26][27][28][29][30].…”

Section: Dimethyl(salicilaldiminato)aluminum Complexesmentioning

confidence: 99%

“…A large variety of aluminum complexes active in the ROP of lactones and lactides have been described with different coordination environments [6][7][8][9][10]. Recent literature reviews described the use of various aluminum complexes as polymerization catalysts [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Aluminum Alkyl Complexes Bearing Salicylaldiminato Ligands: Versatile Initiators in the Ring-Opening Polymerization of Cyclic Esters

Fuoco

Pappalardo

2017

Catalysts

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Linear aliphatic polyesters are degradable thermoplastic polymers, which can be obtained by ring-opening polymerization (ROP) of cyclic esters through a coordination-insertion mechanism. Aluminum based organometallic complexes have a leading position as efficient catalysts for this polymerization process. Aluminumalkyl complexes bearing salicylaldiminato ligands, although less explored, have been shown to be efficient and versatile catalysts for the ROP of various cyclic esters. These species have the potential to function as active catalysts in the ROP because of their less coordinatively saturated nature with respect to analogous SALEN-type complexes. They have been used as efficient catalysts in the ROP of commercially available cyclic esters, such as ε-caprolactone, L-lactide, rac-lactide, and glycolide. Moreover, they resulted in efficient catalysts for the ROP of cyclic esters with large ring-size and for the ROP of functionalized lactide. Furthermore, they have been used in the co-and ter-polymerization of various cyclic esters affording well controlled polymerization and a plethora of microstructural architectures, ranging from random to block to multiblock.

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Recent developments in main group metal complexes catalyzed/initiated polymerization of lactides and related cyclic esters

Cited by 747 publications

References 62 publications

A Comparison of Gallium and Indium Alkoxide Complexes as Catalysts for Ring-Opening Polymerization of Lactide

A Comparison of Gallium and Indium Alkoxide Complexes as Catalysts for Ring-Opening Polymerization of Lactide

Computational Studies on the Selective Polymerization of Lactide Catalyzed by Bifunctional Yttrium NHC Catalyst

Aluminum Alkyl Complexes Bearing Salicylaldiminato Ligands: Versatile Initiators in the Ring-Opening Polymerization of Cyclic Esters

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