Polymerization of lactide and related cyclic esters by discrete metal complexes
01 Jan 2001-Journal of The Chemical Society-dalton Transactions (The Royal Society of Chemistry)-Iss: 15, pp 2215-2224
TL;DR: In this article, a systematic approach to the deconvolution of catalyst structure/reactivity relationships is presented and key design criteria required for the development of new catalysts that exert control over the molecular parameters of polyesters and related copolymers have been revealed.
Abstract: This perspective highlights recent research on the preparation of polyesters by the ring-opening polymerization of cyclic esters employing well-characterized metal complexes. Particular focus is placed on the preparation of polylactide because of environmental advantages: it is biodegradable and its feedstock, lactide, is a renewable resource. A recurring theme is the correlation of precatalyst structure, often by X-ray crystallography, with polymerization activity and selectivity. Through this systematic approach to the deconvolution of catalyst structure/reactivity relationships, improved mechanistic understanding has been attained and key design criteria required for the development of new catalysts that exert control over the molecular parameters of polyesters and related copolymers have been revealed.
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TL;DR: This paper presents the design of highly efficient families of “living” polymerization strategies for the synthesis of block, graft, and star polymers through controlled methods for the controlled synthesis of dendritic macromolecules.
Abstract: Modern synthetic methods have revolutionized polymer chemistry through the development of new and powerful strategies for the controlled synthesis of complex polymer architectures. 1-5 Many of these developments were spawned by new classes of transition metal catalysts for the synthesis of new polyolefin microstructures, 5 the design of highly efficient families of “living” polymerization strategies for the synthesis of block, graft, and star polymers, 6-12 controlled methods for the synthesis of dendritic macromolecules, 3,13,14
1,231 citations
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TL;DR: Well-defined catalysts for epoxide-CO(2) copolymerization and related reactions are reviewed here.
Abstract: Most synthetic polymers are made from petroleum feedstocks. Given the non-renewable nature of these materials, there is increasing interest in developing routes to polymeric materials from renewable resources. In addition, there is a growing demand for biodegradable polymeric materials. Polycarbonates made from CO(2) and epoxides have the potential to meet these goals. Since the discovery of catalysts for the copolymerization of CO(2) and epoxides in the late 1960's by Inoue, a significant amount of research has been directed toward the development of catalysts of improved activity and selectivity. Reviewed here are well-defined catalysts for epoxide-CO(2) copolymerization and related reactions.
1,033 citations
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945 citations
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TL;DR: The field of polymers derived from non-petrochemical feedstocks is gaining a great deal of momentum from both a commercial and academic sense using annually renewable feedstocks such as biomass, for the production of new plastics can have both economic and environmental benefits as mentioned in this paper.
Abstract: The field of polymers derived from non‐petrochemical feedstocks is gaining a great deal of momentum from both a commercial and academic sense Using annually renewable feedstocks, such as biomass, for the production of new plastics can have both economic and environmental benefits Fundamental research in the production, modification, property enhancement, and new applications of these materials is an important undertaking The new materials, concepts, and utilizations that result from these efforts will shape the future of polymers from renewable resources This issue of Polymer Reviews focuses on the production and properties of renewable resource polymers and highlights current trends and research directions
900 citations
Cites background from "Polymerization of lactide and relat..."
...There has been much effort over the past decade on the development of new catalysts for the controlled polymerization of lactide and other cyclic esters, and several key reviews have appeared.(6,7) There are myriad studies centered in the use of inorganic complexes in the ring-opening polymerization of cyclic esters....
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TL;DR: In this article, the ring-opening polymerization of cyclic monomers is used as a representative polymerization process to illustrate some of the features of organic catalysts and initiators and compare them to metal-based approaches.
Abstract: Organocatalysis offers a number of opportunities in polymer synthesis and was among the earliest methods of catalyzing the synthesis of polyesters. In the following Perspective we attempt to highlight the opportunities and challenges in the use of organic molecules as catalysts or initiators for polymerization reactions. The ring-opening polymerization of cyclic monomers is used as a representative polymerization process to illustrate some of the features of organic catalysts and initiators and to compare them to metal-based approaches. The convergence of convenience, functional group tolerance, fast rates, and selectivities will continue to drive innovations in polymerization catalysis, and it is our perspective that organocatalysis will continue to play an important role in these developments.
749 citations
References
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TL;DR: Polylactic acid is proving to be a viable alternative to petrochemical-based plastics for many applications It is produced from renewable resources and is biodegradable, decomposing to give H2O, CO2, and humus, the black material in soil as mentioned in this paper.
Abstract: Polylactic acid is proving to be a viable alternative to petrochemical-based plastics for many applications It is produced from renewable resources and is biodegradable, decomposing to give H2O, CO2, and humus, the black material in soil In addition, it has unique physical properties that make it useful in diverse applications including paper coating, fibers, films, and packaging (see Figure)
2,537 citations
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TL;DR: The substituents on the beta-diiminate ligand exert a significant influence upon the course of the polymerizations, affecting both the degree of stereoselectivity and the rate of polymerization.
Abstract: A series of zinc(II) and magnesium(II) alkoxides based upon a β-diiminate ligand framework has been prepared. [(BDI-1)ZnOiPr]2 [(BDI-1) = 2-((2,6-diisopropylphenyl)amido)-4-((2,6-diisopropylphenyl)...
1,088 citations
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TL;DR: A chiral Schiff's base/aluminium alkoxide initiator bearing a ligand derived from R-(+)-1,1′-binaphthyl-2,2′-diamine was synthesized and used for the stereoelective polymerization of rac-(D,L)-lactide as discussed by the authors.
Abstract: A chiral Schiff's base/aluminium alkoxide initiator bearing a ligand derived from R-(+)-1,1′-binaphthyl-2,2′-diamine was synthesized and used for the stereoelective polymerization of rac-(D,L)-lactide. Rather high stereoelectivity is observed: a polymer with 88% enantiomeric enrichment in D units is obtained at 19% conversion. At high conversions a stereocomplex between D- and L-enriched stereocopolymers is formed. The polymerization reaction shows living type features, and narrow molecular weight distributions (Mw/Mn = 1,05–1,30) are obtained up to very high conversions. This indicates that transesterification reactions do not occur significantly with this sterically hindered initiator.
550 citations