Glossary of Terms Related to Kinetics, Thermodynamics, and Mechanisms of Polymerization
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Lecture1541230922.Pdf
MODULE-1 Introduction: -The macromolecules are divided between biological and non-biological materials. The biological polymers form the very foundation of life and intelligence, and provide much of the food on which man exists. The non-biological polymers are primarily the synthetic materials used for plastics, fibers and elastomers but a few naturally occurring polymers such as rubber wool and cellulose are included in this class. Today these substances are truly indispensable to mankind because these are essential to his clothing,shelter, transportation, communication as well as the conveniences of modern living. Polymer Biological Non- biological Proteins, starch, wool plastics, fibers easterners Note: Polymer is not said to be as macromolecule, because polymer is composedof repeating units whereas the macromolecules may not be composed of repeating units. Definition: A polymer is a large molecule built up by the repetition of small, simple chemical units known as repeating units which are held together by chemical covalent bonds. These repeating units are called monomer Polymer – ---- poly + meres Many parts In some cases, the repetition is linear but in other cases the chains are branched on interconnected to form three dimensional networks. The repeating units of the polymer are usually equivalent on nearly equivalent to the monomer on the starting material from which the polymer is formed. A higher polymer is one in which the number of repeating units is in excess of about 1000 Degree of polymerization (DP): - The no of repeating units or monomer units in the chain of a polymer is called degree of polymerization (DP) . The molecular weight of an addition polymer is the product of the molecular weight of the repeating unit and the degree of polymerization (DP). -
1 Introduction to Synthetic Methods in Step-Growth Polymers
1 Introduction to Synthetic Methods in Step-Growth Polymers Martin E. Rogers Luna Innovations, Blacksburg, Virginia 24060 Timothy E. Long Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 S. Richard Turner Eastman Chemical Company, Kingsport, Tennessee 37662 1.1 INTRODUCTION 1.1.1 Historical Perspective Some of the earliest useful polymeric materials, the Bakelite resins formed from the condensation of phenol and formaldehyde, are examples of step-growth processes.1 However, it was not until the pioneering work of Carothers and his group at DuPont that the fundamental principles of condensation (step-growth) processes were elucidated and specific step-growth structures were intentionally synthesized.2,3 Although it is generally thought that Carothers’ work was lim- ited to aliphatic polyesters, which did not possess high melting points and other properties for commercial application, this original paper does describe amor- phous polyesters using the aromatic diacid, phthalic acid, and ethylene glycol as the diol. As fundamental as this pioneering research by Carothers was, the major thrust of the work was to obtain practical commercial materials for DuPont. Thus, Carothers and DuPont turned to polyamides with high melting points and robust mechanical properties. The first polymer commercialized by DuPont, initiating the “polymer age,” was based on the step-growth polymer of adipic acid and hexamethylene diamine — nylon 6,6.4 It was not until the later work of Whin- field and Dickson in which terephthalic acid was used as the diacid moiety and the benefits of using a para-substituted aromatic diacid were discovered that polyesters became commercially viable.5 Synthetic Methods in Step-Growth Polymers. -
Living Radical Polymerization: a Review
Tran DF sfo P rm Y e Y r B 2 B . 0 A Click here to buy w w m w co .A B BYY. 141 Journal of Scientific Research Vol. 56, 2012 : 141-176 Banaras Hindu University, Varanasi ISSN : 0447-9483 LIVING RADICAL POLYMERIZATION: A REVIEW Vivek Mishra and Rajesh Kumar* Organic Polymer Laboratory, Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi-221005, E-mail: [email protected] E-mail: [email protected] 1. Introduction Free radical polymerization is one of the most widely employed polymerization techniques. This technique is applied to prepare latexes to be used in paints, high ® molecular weight poly (methyl methacrylate) for safety glass (Plexiglas ), or foamed poly (styrene) to be applied in coffee cups. Some advantages of radical polymerizations, with respect to other techniques, are the relative insensitivity to impurities, the moderate reaction temperatures and the multiple polymerization processes available, e.g., bulk, solution, precipitation or emulsion polymerization. Some disadvantages related to the mechanism of free radical polymerization is the poor control of the molecular weight and the molecular weight distribution, and the difficulty (or even impossibility) of preparing well-defined copolymers or polymers with a predetermined functionality. To overcome these disadvantages new techniques were developed based on either reversible deactivation of polymer radicals or a degenerative transfer process, called ‘living’ or controlled radical polymerizations (CRP). It will be worthwhile to discuss the significance of the living radical polymerization process because of which it was selected for the present investigation. Controlled radical polymerizations, like atom transfer radical polymerizations (ATRP) [1], reversible addition-fragmentation chain transfer polymerization (RAFT) [2, 3], and nitroxide-mediated polymerizations (NMP) [4] represent key strategies for the preparation of polymers with narrow molecular weight distributions. -
Molecular Weight Distributions in Ideal Polymerization Reactors
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CONICET Digital Latin American Applied Research 41: 389-401(2011) MOLECULAR WEIGHT DISTRIBUTIONS IN IDEAL POLYMERIZATION REACTORS. AN INTRODUCTORY REVIEW G.R. MEIRA† and H.M. OLIVA‡ † INTEC (Univ. Nac. del Litoral and CONICET), Santa Fe (3000), Argentina. [email protected] ‡ Escuela de Ingeniería Química, Univ. del Zulia, Maracaibo, Venezuela. [email protected] Abstract The ultimate aim of polymerization million tons by 2015. In volume, the annual production reaction engineering is the production of polymers of polymers exceeds that of the 2 most important met- with tailor-made properties. An introductory review als: iron and aluminum. The raw materials for the pro- into this field is presented, with emphasis on the ef- duction of around 95% of all synthetic polymers are fects on the molar mass distribution (MMD), of the non-renewable sources (fossil oil, gas, and coal). sought combination of polymerization mechanism, Polymerization Reaction Engineering deals with reactor type, and reactor control. Three ideal poly- problems involving the measurement, mathematical merization mechanisms are analyzed: free-radical, modeling, optimization, and control of industrial poly- “living” anionic, and step-growth. “Living” anionic merization processes. It aims at improving both the and step-growth polymerizations are similar in that productivity of the polymerization process and the qual- their growing chains remain reactive while inside the ity of the produced polymer. Some general references reactor; and for these systems the narrowest MMDs on this area are: Ray (1972), Reichert and Moritz are produced in reactors with narrow residence time (1989), Hamielec and Tobita (1992), Kiparissides distributions (RDT); i.e.: batch or continuous tubu- (1996), Ray et al. -
Polymerization Reactions and Techniques
Structure and Properties of Engineering Polymers Lecture: Polymerization Reactions and Techniques Nikolai V. Priezjev Textbook: Plastics: Materials and Processing (Third Edition), by A. Brent Young (Pearson, NJ, 2006). Polymerization Reactions and Techniques Step-growth polymerization or condensation polymerization Chain-growth polymerization or addition polymerization https://www.slideshare.net/NikolaiPriezjev Step-Growth Polymerization • Formerly: Condensation polymerization (Carothers, 1931) • Monomers are difunctional — each has two reactive functional groups • Chain growth occurs through coupling (condensation, addition) reactions • [Monomer] decreases rapidly before any high-MW polymer is formed • Rate of polymerization is highest at outset, decreases as chain ends are consumed => long reaction times Step-Growth Polymerization (cont.) Schematic: https://www.slideshare.net/NikolaiPriezjev Step-Growth Polymerization (cont.) Example: Step-Growth Polymerization (cont.) Degree of Polymerization: Xn = average number of monomers per chain Representative Step-Growth Reactions https://www.slideshare.net/NikolaiPriezjev Predicting Molar Mass in Step-Growth Polymerization Xn = average number of monomers per chain Step-Growth Reactions: MW Distribution MW=Molecular Weight MWD=Molecular Weight Distribution https://www.slideshare.net/NikolaiPriezjev Step-Growth Reactions: Molecular Weight Control 1 https://www.slideshare.net/NikolaiPriezjev Step-Growth Reactions: Molecular Weight Control Step-Growth Reactions: Molecular Weight Control Producing -
Chemical Engineering 160/260 Polymer Science and Engineering
Chemical Engineering 160/260 Polymer Science and Engineering LectureLecture 33 -- MolecularMolecular WeightWeight AveragesAverages andand DistributionsDistributions JanuaryJanuary 22,22, 20012001 Reading:Reading: SperlingSperling,, ChapterChapter 33 Outline ! Step-growthStep-growth polymerizationpolymerization ! NumberNumber distributiondistribution andand numbernumber averageaverage molecularmolecular weightweight ((MMn)) ! WeightWeight distributiondistribution andand weightweight averageaverage molecularmolecular weightweight (M(Mw)) ! BreadthBreadth ofof distributiondistribution -- polydispersitypolydispersity ! IntegralIntegral expressionsexpressions Generic Scheme for A-B Reaction Features of Step-Growth Polymerization ! Growth proceeds by a step-wise intermolecular reaction. ! Growth involves monomer units reacting with each other or with oligomers of any size. ! The reactivity of a functional group is independent of the size of the molecule to which it is attached. ! The reactivity of a functional group is independent of whether another functional group has previously reacted. ! High-molecular weight polymers are only produced after a high degree of conversion of functional groups. ! Step-growth polymerizations often involve an equilibrium between reactants and products, leading to reversibility and to interchange reactions. Self Condensation of HO(CH2)9COOH Mn Number of ester Spinnability groups 4,170 25 Absent 5,670 33 Short fibers, no cold drawing 7,330 43 Long fibers, no cold drawing 9,330 55 Long fibers that cold draw 16,900 99 Easy to spin and cold draw 25,200 148 Spins at T>210C and cold draws Data from Organic Chemistry of Synthetic High Polymers, R. W. Lenz, 1967, p 66. Arithmetic Mean Our objective is to develop a parameter to express the central tendency of the molecular weight distribution. Assume a unit volume of a sample of N polymer molecules in which there are nj molecules with molecular weight Mj. -
Kinetics of Different Methods of Polymerization
Technische Universität Berlin Institut für Chemie Polymerization Technology Karl-Heinz Reichert Reinhard Schomäcker Third Edition SS 2017 Preface This teaching booklet has been written for students attending the Master Program of Polymer Science, established as a joint program by four universities in the cities of Berlin and Potsdam. This text book focuses on fundamental aspects of polymerization reaction engineering. In the development of a polymerization process the type of reactor and its mode of operation are key factors, which not only affect reactor performance and safety, but also to a large extend the quality of the polymeric product. This is due to the fact that polymers are non uniform materials and the degree of non uniformity is affected by chemistry and reaction engineering conditions as well. I hope that the contents of this text book will be of help to those students who will be envolved in large scale synthesis of polymers in times to come. I would like to thank my secretary Veronika Schott for writing the manuscript of this booklet and especially for her patience with respect to numerous changes of the text, which I have made all the time. Thanks also go out to Monika Klein, who drew all the figures presented in this book and Scott Kibride who improved the English language. Finally we would like to thank all my former PhD students and many of our colleagues for some of their scientific results, which we have used in this text book. Karl Heinz Reichert Berlin in October 2002 Reinhard Schomäcker Berlin in April 2017 TABLE OF CONTENTS 1. -
Controlled/Living Radical Polymerization: Features, Developments, and Perspectives
www.aladdin-e.com Address:800 S Wineville Avenue, Ontario, CA 91761,USA Website:www.aladdin-e.com Email USA: [email protected] Email EU: [email protected] Email Asia Pacific: [email protected] Controlled/living radical polymerization: Features, developments, and perspectives Abstract Recent mechanistic developments in the field of controlled/living radical polymerization (CRP) are reviewed. Particular emphasis is placed on structure–reactivity correlations and ‘‘rules’’ for catalyst selection in atom transfer radical polymerization (ATRP), for chain transfer agent selection in reversible addition-fragmentation chain transfer (RAFT) polymerization, and for the selection of an appropriate mediating agent in stable free radical polymerization (SFRP), including organic and transition metal persistent radicals. Novel methods of fine tuning initiation, activation, and deactivation processes for all techniques are discussed, including activators regenerated by electron transfer (ARGET) and initiators for continuous activator regeneration (ICAR) ATRP, whereby Cu catalyst concentrations in ATRP can be lowered to just 10 ppm. Progress made in each technique related to the synthesis of both high and low molecular weight polymers, end functional polymers, block copolymers, expanding the range of polymerizable monomers, synthesis of hybrid materials, environmental issues, and polymerization in aqueous media is thoroughly discussed and compared. Contents 1. Introduction ..............................................................................................................................................................