Download or read book Synthesis and Characterization of Lanthanide Phenolate Compounds and Their Catalytic Activity Towards Ring opening Polymerization of Cyclic Esters written by Pascal I. Binda and published by . This book was released on 2008 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis Characterization and Oxidation of New Divalent Lanthanide Bis phenolate Complexes and Their Applications in the Ring Opening Polymerization of Cyclic Esters written by Divine Timah Dugah and published by . This book was released on 2009 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Biometal Catalyzed Ring opening Polymerization of Cyclic Esters written by Osit Karroonnirun and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Biodegradable polyesters represent a class of extremely useful polymeric materials for many applications. Among these polyesters, the biodegradable and biocompatible, polylactide is very promising for many applications in both medical and industrial areas. Other biodegradable polymers such as polytrimethylene carbonate, polybutyrolactone, polyvalerolactone, and polycaprolactone can be blended or copolymerized with polylactide to fine tune the properties to fit the needs for their applications. The properties of these polymers and copolymers depend upon the tacticity of the polymers which can be directly controlled by the catalysts used for polymer production. Therefore, it has been of great interest to develop new selective catalytic systems for the ring-opening polymerization of lactide and other cyclic monomers. This dissertation focuses on developing new zinc and aluminum complexes and studying their selectivity and reactivity of these complexes for the ring-opening polymerization of lactide and other cyclic monomers, i.e. trimethylene carbonate, beta-butyrolactone, delta-valerolactone, and epsilon-caprolactone. Herein, aspects of the ring-opening polymerization of lactide and other cyclic monomers utilizing novel zinc and aluminum complexes will be discussed in detail. In the process for the ring-opening polymerization of lactide, chiral zinc half-salen complexes derived from natural amino acids have shown to be very active catalysts for producing polymers with high molecular weight and narrow polydispersities at ambient temperature. The chiral zinc complexes were found to catalyze rac-lactide to heterotactic polylactides with Pr values ranging from 0.68-0.89, depending on the catalyst and reaction temperature employed during the polymerization process. The reactivities of the various catalysts were greatly affected by substituents on the Schiff base ligands, with sterically bulky substituents being rate-enhancing. Furthermore, a series of both chiral and achiral aluminium half-salen complexes have been synthesized and characterized. These aluminum complexes all showed moderate selectivity to the ring-opening polymerization of rac-lactide to produce isotactic polylactide with Pm value up to 0.82 in toluene at 70 degrees C. Moreover, some of the studied aluminum complexes displayed epimerization of rac-lactide to meso-lactide during the polymerization process. Kinetic studies for the ring-opening polymerization of lactide utilizing these zinc and aluminum complexes are included in this dissertation. Along with these studies, the copolymerization of lactide with epsilon-caprolactone and delta-valerolactone will also be presented.

Download or read book Synthetic Biodegradable and Biobased Polymers written by Andreas Künkel and published by Springer Nature. This book was released on 2023-12-28 with total page 403 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents the recent developments in synthetic biodegradable and biobased polymers. The syntheses of many polymer types such as polyesters and polyamides, and also their processing technologies are discussed herein, and new aspects from fundamental and from industrial research are covered. This combination of both perspectives within this volume will be of interest for many research scientists from academia and industry and also for lectures and teachers. Chapters ''BioPBSTM (Polybutylene succinate)'' and ''Polymer biodegradability 2.0: A holistic view on polymer biodegradation in natural and engineered environments'' are available open access under a Creative Commons Attribution 4.0 International License via link.springer.com. For further details see license information in the chapter.

Download or read book Lanthanides Chemistry and Use in Organic Synthesis written by Shu Kobayashi and published by Springer. This book was released on 2003-07-01 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: With contributions by numerous experts

Download or read book New Lanthanide Complexes as Polymerisation Catalysts written by Hellen Elizabeth Dyer and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This Thesis describes the synthesis and characterisation of a series ofbisphenolate supported samarium borohydride, amide and zwitterionic rare earth complexes and their ability to effect the ring opening polymerisation (ROP) of cyclic esters and methylmethacrylate (MMA). Chapter 1 introduces ROP from both an industrial and an academic perspective and describes in detail the research in this area, with emphasis on rare earth initiators. The lanthanide elements and the bisphenolate ligand are also introduced. Chapter 2 describes the synthesis and characterisation ofbisphenolate supported samarium borohydride and silylamide complexes. Chapter 3 describes the ability of a selection of samarium borohydride and amide complexes to effect the ROP of the cyclic esters s-caprolactone (f-CL) and rac- lactide (rac-LA). Emphasis is placed on the effect that the nature of the bisphenolate pendant arm and the initiating moiety has on the polymerisation process. Chapter 4 describes the synthesis and characterisation of rare earth zwitterionic complexes and the ability ofa range of these complexes to effect the ROP of s-Cl. and rac-lactide. Mechanistic aspects ofthe ROP process will be discussed, as will the ability of these complexes to yield amide functionalised poly(rac-LA). Chapter 5 describes the ability ofbisphenolate samarium borohydride complexes to initiate the polymerisation of MMA. The experimental work conducted as part of this study is further supported computationally by calculations at the DFT level, both aspects will be described. Aspects concerning the synthesis and characterisation of the related borohydride derivative [Sm(N2siMe3NNPY)(BH4)2Li]oo will also be emphasised. Chapter 6 contains full experimental and characterising data for all 0 f the new compounds reported in this Thesis. Appendices A- T contain tables of selected crystallographic data for all new crystallographically characterised complexes described in this Thesis (partially on CD).

Download or read book Olefin Metathesis and Polymerization Catalysts written by Yavuz Imamogammalu and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 567 pages. Available in PDF, EPUB and Kindle. Book excerpt: Olefin metathesis reaction can be considered as one of the most successful organic reactions with many applications in the low molecular weight range and also in the polymer field. The use of catalysts with their selective and effective transformation properties in olefin metathesis I polymerization systems is a growing interest. There has been great effort and competition in developing active and commercially useful catalysts. The main aim of this ASI was to gather several research groups and also the people from industry. to present existing knowledge and latest results in the field. A wide range of topics through homogeneous and heterogeneous aspects have been considered. Attention has been drawn to the metal-carbene and metallacyclobutane complexes as active species, the initiation mechanisms, the stereochemistry and thermodynamics of these reactions. New catalytic systems for the metathesis of alkenes and alkynes and fot' ring opening polymeriZation I block copolymerization reactions have been introduced. Spectroscopic studies for the characteriZation of catalysts, simulation studies explaining the function of chain carrier species and polymer degradation have also been covered. A detailed industrial report concerning the patents and applications in olefin metathesis I cyc1001efin polymerization area, fabrication and derivation has been presented. This volume contains the main lectures and seminars given at the NATO Advanced Study Institute on " Olefin Metathesis and Polymerization Catalysts: Synthesis, Mechanism and Utilization", held at Akcay. Babkesir. Turkey between 10th and 22nd September 1989.

Download or read book Metallic Catalysts for Ring Opening Polymerization of Cyclic Esters and Related Compounds written by Isha Jain and published by Mohammed Abdul Sattar. This book was released on 2024-03-24 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymers are extremely useful materials that have become an irreplaceable component of modern life. Synthetic polymers exhibit a multitude of applications in medicine, agriculture, packaging, and textile industries. Synthetic polymers like poly(ethylene) (PE), poly(propylene) (PP) and poly(styrene) (PS), poly (vinyl chloride) (PVC), poly (ethylene terephthalate) (PET), poly (urethane) (PU), etc. are obtained from petroleum-based sources and cover 90% of total synthesized plastics. A recent report revealed that global plastic production has increased from 270 million metric tons in the year 2010 to 370 million metric tons in 2020. The annual production volumes are expected to increase further in the coming years, approximately 590 million metric tons by the year 2050. Due to the non-biodegradability of synthetic polymers, each year post-consumer plastics generate huge waste which is diverted to landfills or the natural environment. These are pervasive and persistent in the environment and cause ecological and health risks at a global scale. In the recent past, a lot of scientific research efforts are devoted to replace non- biodegradable petroleum-based resources with renewable biodegradable polymers, and the polymer industry has witnessed remarkable progress. The bioplastics are rapidly gaining commercial interest globally, which is indicated by the up-trend in the market size which rose up to USD 13.11 billion in 2022 and expected to hit USD 46.1 billion by 2030. Estimated annual growth rate (CAGR) is expected to retain a value of 17.02% from 2022 to 2030. Among the various classes of biodegradable polymers, aliphatic polyesters are of leading interest since hydrolytic or enzymatic cleavage yields hydroxy carboxylic acids which can be metabolized to produce water and carbon dioxide as degradation products without formation of any toxic side product. For example, PLA (polylactide) is an attractive renewable alternative to the petro-based polymers, it decomposes in biological environments or in the presence of microorganisms to H20, C02 and humus to soil.

Download or read book Studies of the Ring opening Polymerization of Cyclic Ethers and Esters by Coordinate Catalysis written by Diana Navarro-Llobet and published by . This book was released on 2002 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Book of Abstracts written by and published by . This book was released on 2000 with total page 778 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Enzymatic polymerization of phenolic compounds by oxidoreductases written by Mohamed Ghoul and published by Springer Science & Business Media. This book was released on 2012-02-09 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: The enzymatic polymerization of phenolic compounds has been generating interest in several fields such as food, cosmetics, and pharmaceuticals. These compounds are employed for their antioxidant properties; however, their use is limited by their low solubility and thermal stability. Polymerization can improve their solubility and their thermal stability though and create new properties which are dependent on the molecular mass and the structure of polymers. The reaction yield, the polydispersity, the molecular mass, the structure and the properties of synthesized polymers can be controlled by the mode of control of the reaction and by the reaction conditions. Enzymatic polymerization of phenolic compounds by oxidoreductases analyze the processes used and the key factors (temperature, solvent, origin of the enzyme, structure of the substrate, reactor design, ...) which control the polymerization of phenolic species by these oxidoreductase enzymes in order to obtain polymers with desired characteristics and properties.

Download or read book Mechanistic Insights Towards New Reactions and Materials written by Matthew Karl Kiesewetter and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalysis is the enabling science of polymer synthesis, and new catalytic mechanisms yield new materials. The developement of organocatalysts for polymer synthesis has, particularly in the last decade, spawned an impressive array of new catalysts, processes and mechanistic insights. While the focus of most recent research in organocatalysis has concentrated on enantioselective synthesis of small molecules, organocatalysis offers a number of opportunities in polymer synthesis and was among the earliest methods of catalyzing the synthesis of polyesters. The enthalpy of ring opening of cyclic esters or carbonates drives the majority of organocatalyic polymerization reactions catalyzed by a still-evolving array of organocatalysts. Organocatalysts are thought to effect polymerization of cyclic esters by several mechanisms. Some proceed via a monomer activated mechanism whereby the catalyst activates the cyclic ester towards transesterification to the polymer chain. Others operate by an alcohol activation mechanism where the alcoholic end group of the growing polymer chain is activated to induce transesterification. Some are thought to be operative by a combination of these mechanisms. The unique reactivity offered by organocatalysts has provided access to precisely controlled macromolecular architectures and well-defined (co)polymers including a wide array of functionality. The notion that rate must be sacrificed to implement organocatalysts is fading with the discovery of transesterification organocatalysts that rival in reaction rate even the most active metal-containing catalysts. Cyclopentadienyl ruthenium complexes with quinaldic acid-type ligands are robust allylation catalysts in alcoholic solvents, but they are sensitive to dissolved oxygen, requiring reactions to be conducted in an inert atmosphere. Moving from alcoholic to neat aqueous solvents decreases the rate of deallylation but allows the reaction to be conducted in air without loss of catalyst activity over the course of the reaction. These complexes are also effective for the formation of allyl ethers, allowing the synthesis of poly(2,5-dihydrofuran) from the condensation polymerization of 2-cis-butene-1,4-diol. This material was previously deemed inaccessible via traditional polycondensation catalysts.

Download or read book Alkene Polymerization Reactions with Transition Metal Catalysts written by Yury Kissin and published by Elsevier. This book was released on 2008-03-10 with total page 607 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past 30 years, the field of alkene polymerization over transition metal catalysts underwent several major changes:1. The list of commercial heterogeneous Ziegler-Natta catalysts for the synthesis of polyethylene and stereoregular polyolefins was completely renewed affording an unprecedented degree of control over the polymer structure.2. Research devoted to metallocene and other soluble transition-metal catalysis has vastly expanded and has shifted toward complexes of transition metals with multidentate ligands.3. Recent developments in gel permeation chromatography, temperature-rising fractionation, and crystallization fractionation provided the first reliable information about differences between various active centers in transition-metal catalysts.4. A rapid development of high-resolution 13C NMR spectroscopy resulted in greatly expanded understanding of the chemical and steric features of polyolefins and alkene copolymers. These developments require a new review of all aspects of alkene polymerization reactions with transition-metal catalysts. The first chapter in the book is an introductory text for researchers who are entering the field. It describes the basic principles of polymerization reactions with transition-metal catalysts, the types of catalysts, and commercially manufactured polyolefins. The next chapter addresses the principal issue of alkene polymerization catalysis: the existence of catalyst systems with single and multiple types of active centers. The subsequent chapters are devoted to chemistry and stereochemistry of elemental reaction steps, structures of catalyst precursors and reactions leading to the formation of active centers, kinetics of polymerization reactions, and their mechanisms. The book describes the latest commercial polymerization catalysts for the synthesis of polyethylenes and polypropylene The book provides a detailed description of the multi-center nature of commercial Ziegler-Natta catalysts. The book devotes specialized chapters to the most important aspects of transition metal polymerization catalysts: the reactions leading to the formation of active centers, the chemistry and stereochemistry of elemental polymerization steps, reaction kinetics, and the polymerization mechanism. The book contains an introductory chapter for researchers who are entering the field of polymerization catalysis. It describes the basic principles of polymerization reactions with transition-metal catalysts and the types of commercially manufactured polyolefins and copolymersThe book contains over 2000 references, the most recent up to end of 2006.

Download or read book Catalytic Olefin Polymerization written by T. Keii and published by Elsevier. This book was released on 1990-09-12 with total page 597 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent development of a new generation of Ziegler-Natta Catalysts using either magnesium dichloride as carrier or methylaluminoxane as cocatalyst has markedly stimulated the research activity in the field of olefin polymerization. These discoveries have not only yielded economical processes for polyolefin production but also opened the way to a new generation of novel polymers. Moreover, the nature of active species is being clarified well by the effort to simplify catalyst systems. The present volume includes 38 papers from the 31 lectures and 18 posters presented at the symposium on `Recent Developments in Olefin Polymerization Catalysts', which covered the following topics: Overview of super-active homogeneous and heterogeneous catalysts, kinetic profile of olefin polymerization including copolymerization, characterization of catalysts and polymers, methods for the determination of active center concentration, role of Lewis bases on the catalysts isospecificity, polymerization mechanisms, and synthetic pathways for functionalized polyolefins. The contents are well balanced between fundamental research and application as well as between homogeneous and heterogeneous catalyst systems.

Download or read book Early Main Group Metal Catalysis written by Sjoerd Harder and published by John Wiley & Sons. This book was released on 2020-04-06 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Early Main Group Metal Catalysis gives a comprehensive overview of catalytic reactions in the presence of group 1 and group 2 metals. Chapters are ordered to reaction type, contain educational elements and deal with concepts illustrated by examples that cover the main developments. After a short introduction on polar organometallic chemistry and synthesis of early main group metal complexes, a variety of catalytic reactions are described, e.g. polymerization of alkenes, hydroamination and phosphination reactions, hydrosilylation, hydroboration and hydrogenation catalysis, as well as enantioselective and Lewis-acid catalysis. The book addresses organic chemists and researchers in industry interested in the state-of-the-art and new possibilities of early main group metal catalysis as well as newcomers to the field. Written by a team of leaders in the field, it is a very welcome addition to the area of main group metal chemistry, and to the field of catalysis.

Download or read book Catalytic Polymerization of Olefins written by T. Keii and published by Elsevier. This book was released on 1986-04-01 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the proceedings of a symposium which was attended by researchers from all over the world who reported on and discussed recent advances in the field of catalytic polymerization of olefins. Over two decades have elapsed since the discovery of the Ziegler-Natta catalyst. Tremendous research effort has been aimed at improving this marvelous catalyst. In twenty-five years since the first publication, more than 15,000 papers and patents on the subject and on related subjects have appeared. This effort has yielded new generations of Ziegler-Natta catalysts with superior activity and stereospecificity. The complexities arising from the heterogeneity of the catalyst, however, have hindered understanding of the catalytic processes which take place on the catalyst surface. Nevertheless, many fundamental features of the catalyst system have now been clarified reasonably well. Recently a highly active homogeneous catalytic system has been developed, which is capable of catalyzing even isotactic polymerization of propene. There is no doubt that this finding will not only contribute to our understanding of the detailed mechanism of polymerization but also stimulate the development of various kinds of tailored polymers. Thus this subject will remain of paramount importance in the development of chemistry and polymer science for a long time to come.

Download or read book Mechanistic Studies of Cyclic Ester Polymerizations by Discrete Metal alkoxide Catalysts written by Laurie Ellen Breyfgle and published by . This book was released on 2005 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: