In the propagation, the chain transfer constant of thiol groups 48 is big enough to quench the carboncentered radicals 31, ensuring controlled stepbystep growth for the synthesis of scps. In polymer chemistry, polymerization is a process of reacting monomer molecules together in a. Other articles where step growth polymerization is discussed. Jan 30, 2012 an introduction to step growth polymerization.
Freeradical polymerization is a very versatile polymerization reaction mechanism that is applicable to a wide range of vinyl monomers. The other process, called step growth polymerization, involves the buildup of molecular weight not in a chainlike fashion but in a stepwise fashion, by the random combination of monomer molecules containing reactive functional groups. In order to start such a reaction, an initiator is needed which has many at best 7 valence electrons like iodine for example. Reaction engineering of step growth polymerization. Very recently, stepgrowth heterogeneous click polymerizations have been developed to fabricate monodisperse, spherical, soft an. Step growth polymerization and condensation polymerization are two different concepts, not always identical. A new approach to control the molecular weight and polymer architecture using the passerini threecomponent stepgrowth polymerization is described. At that time we noted that these classifications could be based on the following. Following a comparison of chain growth and step growth polymerization, focuses on the latter process by describing requirements for high molecular weight, step growth polymerization kinetics, synthesis and molecular weight distribution of some linear step growth polymers, and threedimensional network step growth polymers. Sequentially heterofunctional, topological polymers by. Chain growth polymerization involves the linking together of molecules incorporating double or triple carboncarbon bonds. Monomer does not react with monomer and the different sized species such as dimer, trimer, and nmer do not react with each other. Ppg industries has received a patent for a compound that is comprised of the reaction product of a highly branched polymer having terminal amine functional groups and a lactam, wherein the highly branched polymer is the stepgrowth polymerization reaction product of a polyfunctional first monomer having a first functional group and a polyfunctional second monomer having a. Scribd is the worlds largest social reading and publishing site.
Chain growth system the characteristic of a chain polymer is that polymer growth takes place by monomer reacting only with the reactive centers. Actually, cationic polymer does generate polymer with lower pdi. Predicting chain length distribution in step growth polymerization by monte carlo method wahyudi budi sediawan1, megawati2. Other articles where stepgrowth polymer is discussed.
Get a printable copy pdf file of the complete article 1. A classic example of a stepgrowth polymerization is the esterification reaction between an alcohol and a carboxylic acid. All structured data from the file and property namespaces is available under the creative commons cc0 license. Step growth polymerization, types of monomers, kinetics and equilibrium considerations, closed vs. Starting from an abtype monomer, linear homopolymers, diblock copolymers, as well as starshaped polymers were synthesized in an efficient manner. Stepgrowth polymerization an overview sciencedirect topics. According to their growth mechanisms, polymerization reactions are divided into two. Step polymerisation polymerization materials science.
Reaction engineering of step growth polymerization springerlink. In 1953, paul flory first classified polymerization as stepgrowth polymerization and. Nov 10, 2015 synthesis and phase transition behavior of welldefined polyarylene ether sulfones by chain growth condensation polymerization in organic media. Flory assumed that all steps, that is, the formation of dimers, trimers and so forth, have equal rate constants. In chaingrowth polymerization, the only chainextension reaction is that of attachment of a monomer to an active chain. Made by faculty at the university of colorado boulder department of chemical and biological engineering. Chaingrowth polymerization, by contrast, requires at least three distinctly different kinds of reactions to describe the mechanism. Chapter two, stepgrowth polymerization, version of 1505 75 2 stepgrowth polymerization 2. The resulting polymeric materials can be used in a variety of. Stepgrowth polymerization an overview sciencedirect. Propagation or growth of the active chain by sequential addition of monomers. Stiile colorado state university, fort collins, co 80523 as illustrated in the articles on chain polymerization, a chaingrowth polymerization is one in which each polymer chain, after being started by a free radical initiator, a cationic catalyst or an anionic catalyst, grows rapidly, producing a high molecular weight polymer.
View notes lecture 7 step growth polymerization from bme 510. What links here related changes upload file special pages permanent link page information. In step growth polymerizations, any species monomers, dimers, trimers, etc. The oldest polymers rejuvenated leen billieta, david fournierb, filip du preza, adepartment of organic chemistry, polymer chemistry research group, ghent university, krijgslaan 281 s4bis, b9000 ghent, belgium. Schaefgen and fiery prepared poly ecaprolactam four and eightarm stars using cyclohexanone tetiapropionic acid and. Stepgrowth polymers include polyesters, epoxies, polyurethanes, polyamides, melamine, and phenolic resins. Stepgrowth polymerization article about stepgrowth. This is a stepgrowth polymerization not a chaintransfer or radical polymerization. Significantly, the independent functional groups e.
Simulating step growth polymerization processes using custom models or commercial software can facilitate the efficient design of polymers with highly desirable properties. These are quite general, and can easily be applied in such diverse and emerging fields as polymerization applications in photolithography and microelec tronics. The first six chapters present the principles of step growth polymerization. In contrast to step growth polymerization, highmolecularweight polymer is formed in the early stages of a chain growth polymerization. The functional groups on two monomers react to form a dimer, the dimer reacts with another monomer to form a trimer, and these reactions lead to many monomeric units linked to form an intermediate molecular weight material, which is known as an oligomer, and eventually a polymer. Free radical polymerization is one of the processes of polymer formation.
Simple statistical arguments can be used to show how the distribution develops with extent of reaction. Stiile colorado state university, fort collins, co 80523 as illustrated in the articles on chain polymerization, a chain growth polymerization is one in which each polymer chain, after being started by a free radical initiator, a cationic catalyst or an anionic catalyst, grows rapidly, producing a high molecular weight polymer. Stepgrowth polymerization american chemical society. Stepgrowth polymerization request pdf researchgate. Why pdi is usually greater than 2 in real polymerization. Why pdi is usually greater than 2 in real polymerization system. The mechanism requires that at least two different monomers participate in the reaction. Comparison of common polymerization methods step growth chain growth anionic growth method cons. New polymers synthesis by organocatalyzed stepgrowth. This file is licensed under the creative commons attributionshare alike 4. Stepgrowth polymerization is the method most commonly employed, although hydrogenbonddriven polypseudorotaxane formation has also been reported from preformed polyurethane backbones in combination with 30crown10 or 42crown14 rings.
Simple esterification reactions are known to be catalyzed. These unsaturated monomers the identical molecules that make up the polymers have extra internal bonds that are able to break and link up with other monomers to form a repeating chain, whose backbone typically contains. The age of plastic material has many advantages as it can be tuned very easily unlike metals for example. By varying t open access articles from polymer chemistry. J star polymers are branched molecules with a controlled number of linear arms anchored to one central molecular unit acting as a branch point.
Following a comparison of chaingrowth and stepgrowth polymerization, focuses on the latter process by describing requirements for high molecular weight, stepgrowth polymerization kinetics, synthesis and molecular weight distribution of some linear stepgrowth polymers, and threedimensional network stepgrowth polymers. We performed two synthesizes for polystyrene involving bulk polymerization and emulsion polymerization. Stepgrowth polymerization forms polymers in a manner that is quite different from chaingrowth polymerization. Stepgrowth polymers are formed by independent reaction steps between functional groups of monomer units, usually containing. The other process, called stepgrowth polymerization, involves the buildup of molecular weight not in a chainlike fashion but in a stepwise fashion, by the random combination of monomer molecules containing reactive functional groups. Simultaneous stepgrowth and chaingrowth cationic polymerization of styrenic monomers bearing carbazolyl groups. Durham etheses some studies in stepgrowth photoreductive.
Controlled chain growth polymerization techniques have brought this goal. Step growth polymers include polyesters, epoxies, polyurethanes, polyamides, melamine, and phenolic resins. Understand quantitative model stepgrowth polymerization plans and how to predict properties of the product polymer with the essential information in stepgrowth polymerization process modeling and product design. They are formed most often by reactions between two dissimilar. Long and others published step growth polymerization find, read and cite all the research you need on researchgate. Files are available under licenses specified on their description page. Glossary of basic terms in polymer science iupac recommendations 1996 pdf. Stepgrowth polymerization process modeling and product. In contrast to chain growth reactions, where high molecular mass polymers are formed almost from the start of the reaction, a stepwise reaction results in the molecular mass of the polymer increasing slowly as the reaction progresses. The progress of the polyesterforming reaction can be easily followed by titration of the unreacted acids in the samples removed from the batch at different times. In irreversible stepgrowth polymerization, the molecularweight distribution mwd of the polymers produced can be controlled via the reaction path. Polymer synthesis i am inclined to think that the development of polymerization is. These 3 types of polymerization share 3 common steps. Why does anionic polymerization yield highly monodisperse.
Synthesis, characterization and cleavage of linear. Chapter two, step growth polymerization, version of 1505 75 2 step growth polymerization 2. The active center is ultimately killed off by a termination. Comprehensive heterocyclic chemistry iii, 2008 related terms. Comparison of common polymerization methods stepgrowth chaingrowth anionic growth method cons. Stepgrowth polymerization forms polymers in a manner that. Various polymerization mechanisms such as free radical polymerization, livingcontrolled radical polymerizations and ionic polymerizations, are routinely used for modifying surfaces with thin polymer films to alter a variety of surface properties. In fact polyurethane polymerizes with addition polymerization because its polymerization produces no small molecules, but its reaction mechanism corresponds to a step growth polymerization. Feature article stepgrowth polymerization and click chemistry. One of the two monomers was immobilized as organic ligands of the metalorganic framework mof and polymerized with the mobile guest monomer, resulting in the formation of linear. Free radical polymerization frp is a type of chain growth polymerization, along with anionic, cationic and coordination polymerization. Growth regulated by regulating nucleation of new barbed ends this is done by regulating the amount of active arp23. All molecules present monomer, oligomer, polymer can react with any other molecule.
Properties of polymers, difference of chain growth and. Many naturally occurring and some synthetic polymers are produced by stepgrowth polymerization, e. The mass distribution b shows a single narrow peak which progressively broadens and shifts to high molecular mass as. Combined chain and stepgrowth dispersion polymerization. The number distribution a is shown for three different extents of reaction. The formation of terylene or dacron by the interaction of ethylene glycol and terephthalic acid is an example of this type of polymerisation. Transformation of stepgrowth polymerization into living. Living anionic polymerization has been one of the most important reactions for polymer synthesis since it was first reported by michael szwarc in the 1950s 737475 76 7778798081. The limits of precision monomer placement in chain growth. Mechanism of copolymerization of ethylene and carbon monoxide. Step growth polymerization is the method most commonly employed, although hydrogenbonddriven polypseudorotaxane formation has also been reported from preformed polyurethane backbones in combination with 30crown10 or 42crown14 rings.
Objectives polymers national council of educational. At that time we noted that these classifications could be. Introduction to polymers quiz 7 090225 this week we discussed chain growth polymerization using free radical initiators. Properties of polymers, difference of chain growth and step. Control of molecularweight distribution in stepgrowth. B through individual aa and bb coupling reactions driven by electrochemically positive and negative bias on a self. The polymerization of unsaturated monomers typically involves a chain growth polymerization. As the name suggests, step growth polymerization proceeds in a step wise fashion. In general, two classes of stepgrowth polymerization sgp reactions are considered. Natta of imperia and karl ziegler of germany were awarded the nobel. Step growth polymerization and condensation polymerization step growth polymerization and condensation polymerization are two different concepts, not always identical.
In contrast to stepgrowth polymerization, highmolecularweight polymer is formed in the early stages of a chaingrowth polymerization. The kinetics of the stepgrowth polymerization can be described with florys equal reactivity principle. The active end may be a free radical or an ionic site i. Ppg industries has received a patent for a compound that is comprised of the reaction product of a highly branched polymer having terminal amine functional groups and a lactam, wherein the highly branched polymer is the step growth polymerization reaction product of a polyfunctional first monomer having a first functional group and a polyfunctional second monomer having a second functional.
Predicting chain length distribution in step growth. In contrast, chaingrowth polymerization occurs by introducing an active growth center into a monomer, followed by the addition of many monomers to that center by a chaintype kinetic mechanism. Plastic materials can change its colour without any difficulty, are quite elastic and can therefore be used in several areas and its hardness can be altered by heating the material up and so, it can be reformed easily. Strategic process modeling facilitates accurate prediction of the properties. Chain growth polymerizations require the presence of an initiating molecule that can be used to attach a monomer molecule at the beginning of the polymerization.
Stepgrowth polymerization forms polymers in a manner that is. I guess you are asking about the difference between anionic polymerization an. Glossary of terms related to kinetics, thermodynamics, and mechanisms of polymerization iupac recommendations 2008 pdf. Stepgrowth polymerization refers to a type of polymerization mechanism in which bifunctional or multifunctional monomers react to form first dimers, then trimers, longer oligomers and eventually long chain polymers. Chaingrowth polymerization involves the linking together of molecules incorporating double or triple carboncarbon bonds. In chain growth polymerization, the only chainextension reaction is that of attachment of a monomer to an active chain. Simple and convenient synthetic methods are highly in demand for the preparation and application of patchy particles pps with diverse morphologies, functionalities and behaviors. In stepgrowth polymerizations, any species monomers, dimers, trimers, etc. Aug 12, 2012 chain growth polymerisation the reaction starts rapidly at the beginning and high masses are attained at the end of the reaction about 500000 gmole. Chemical engineering, faculty of engineering, gadjah mada university jl.
A detailed discussion of several important step growth polymeriz ations follows in the next five chapters. Figure 41 molecular mass distributions in step growth polymerization. In general, two classes of step growth polymerization sgp reactions are considered. Lecture 7 step growth polymerization polymer synthesis. Other articles where stepgrowth polymerization is discussed. Other articles where step growth polymer is discussed. Stiile colorado state university, fort collins, co 80523 as illustrated in the articles on chain polymerization, a chaingrowth polymerization is one in which each polymer chain, after being started by a free radical initiator, a cationic catalyst or an anionic catalyst, grows rapidly, producing a high. Chemical engineering, faculty of engineering, semarang state universitybldg. Chapter three, chaingrowth polymerization, version of 1505.
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