Stepgrowth polymerization is the method most commonly employed. In a stepgrowth polymerization, the molecular weight of the polymer chain builds up slowly and there is only one re. The first six chapters present the principles of step growth polymerization. Step growth polymerization, or condensation polymerization, is commonly employed to produce polyesters and nylons. Step growth polymerization an overview sciencedirect topics. All molecules present monomer, oligomer, polymer can react with any other molecule. Step growth polymerization, types of monomers, kinetics and equilibrium considerations, closed vs. Lower yield per reactor volume, reduced reaction rate and average chain length. The mechanism of the polymerization stepwise or chain reaction. In a stepreaction polymerization reaction, sometimes called condensation polymerization, the polymer chains grow by reactions that occur between two molecular species. Synthesis of macromolecules by step growth polymerization 4 4.
Classification of polymerization reaction addition and. Differences between step growth polymerization and chain growth polymerization. Stepgrowth polymerization is also used for preparing a class of adhesives and amorphous solids called epoxy 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. Polymerization proceeds by the reaction of two different functional groups. Step growth polymerization does not require an initiator and occurs between monomers that carry reactive functional groups.
These are quite general, and can easily be applied in such diverse and emerging fields as polymerization applications in photolithography and microelec tronics. 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. Building on concepts presented in an earlier cep article on plastics 1, this article explores some of the most important of those principles related to selecting, sizing, and troubleshooting polymerization reactors. The monomer molecules may be all alike, or they may represent two, three, or more different compounds. Stepgrowth polymerization forms polymers in a manner that. Stepgrowth polymerization journal of chemical education. First of all, it has been shown that this reaction is catalyzed by chain end groups bsi which change in concentration with reaction conversion. The present paper aimed at presenting some important state of art problems on polymerization reaction engineering, and discussing, through some selected examples, on future directions and.
Stepgrowth polymerization process modeling and product design kevin seavey, y. An understanding of processes occurring in the polymerization reactor is therefore crucial to achieving efficient, consistent, safe and environmentally friendly production of polymeric materials. The number distribution a is shown for three different extents of reaction, the mass distribution b shows a single narrow peak which progressively broadens and shifts to high molecular mass as. The quantitative match of the prism assembly statistics with reactionlimited stepgrowth polymerization has implications potentially generalizable to other. 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. Once the propagation reaction within a given polymer chain is stopped either by a termination or chaintransfer step, usually no further chain growth occurs. An analysis of caprolactam polymerization reaction engineering viewpoint, however, several features are important. Reaction engineering of step growth polymerization springerlink. Small molecules such as water are eliminated by the chemical reaction in step growth polymerization. Stepgrowth polymerization an overview sciencedirect topics. During propagation, only monomers react to the active site at the end of the growing chain. Request pdf stepgrowth polymerization stepgrowth polymerization is a very. The two most important stepgrowth polymerizations are condensation and addition polymerization. Stepgrowth polymerization of inorganic nanoparticles science.
Once the growth of a chain is initiated by formation of an active center, chain propagation is usually rapid by addition of a sequence of monomers. Many polymers with real world applications are formed as a result of step growth polymerisation. When discussing the progress of step polymerization, it is not meaningful to use conversion of monomer as a measure because the reaction will still proceed even though all the monomer has been consumed. Small molecules such as water are eliminated by the chemical reaction in stepgrowth polymerization. Control of molecularweight distribution in stepgrowth. Stepgrowth polymerization of inorganic nanoparticles. The two most important step growth polymerizations are condensation and addition polymerization. Monomer disappears rapidly, but molecular weight builds up slowly. Ch 26 stepgrowth polymers condensation polymerization. The past decade has witnessed great progress in nanoparticle selfassembly, yet the quantitative prediction of the architecture of nanoparticle ensembles and of the kinetics of their formation remains a challenge. Reaction engineering of step growth polymerization santosh. College level organic chemistry 2 chapter 26 including closed captioned video. Step growth polymerization process modeling and product design kevin seavey, y.
We shall sometimes use the terms step growth and condensation polymers as synonyms, although step growth polymerization. So far we have seen that there are two types of the polymerization reaction, how the polymerization of monomers take place and the addition and condensation mechanism. The literature in polymerization reaction engineering has bloomed sufficiently in. The concepts here are explained in brief, for further details and clarification on the topic of polymerization reaction download byjus the. We report on the marked similarity between the selfassembly of metal nanoparticles and reactioncontrolled stepgrowth polymerization. Stepgrowth polymerization request pdf researchgate. Stepgrowth polymerization forms polymers in a manner that is. In fact polyurethane polymerizes with addition polymerization because its polymerization produces no small molecules, but its reaction mechanism corresponds to a step growth polymerization. Controlled stepgrowth polymerization ccs chemistry. Stepgrowth polymerscondensation polymers chemistry. In chain growth or chain polymerization, the only chainextension reaction step is the addition of a monomer to a growing chain with an active center such as a free radical or ion. In this context, the present manuscript investigates the stepgrowth polymerization of polyethylene 2,5furandicarboxylate, pef, a furanic polyester with structural similarity to polyethylene terephthalate, pet, using ethylene glycol eg, and 2,5furandicarboxylic acid fdca as monomers.
Chemical engineering 160260 polymer science and engineering. Equilibrium step condensation polymerizations, interchange reactions. The science and engineering of materials, pws publishing company, 1994. The literature in polymerization reaction engineering has bloomed sufficiently in the. The initiation, propagation, and termination steps are distinctly different. The mw and the mw distribution, referred to as polydispersity, are two fundamental factors that dictate the physical nature of polymeric materials. Modeling and control of polymer properties 149 korean j.
Differences between stepgrowth polymerization and chaingrowth polymerization step growth chain growth growth throughout matrix rapid loss of monomer early in the reaction similar steps repeated throughout reaction process average molecular weight increases slowly at low conversion and high. Step reactions require bifunctional or polyfunc tional monomers, while chain reactions require the presence of an initiator. Figure 1 features a few important examples related to polyesters, polyamides, and polyurethanes. Step polymerisation polymerization materials science. This imparts an autocatalytic character to the reaction.
Stepgrowth polymerization does not require an initiator and occurs between monomers that carry reactive functional groups. In chaingrowth or chain polymerization, the only chainextension reaction step is the addition of a monomer to a growing chain with an active center such as a free radical or ion. The distinct initiation, propagation, and termination steps of chaingrowth polymerization are meaningless in stepgrowth polymerization. Understand quantitative model step growth polymerization plans and how to predict properties of the product polymer with the essential information in step growth polymerization process modeling and product design. Each stage in stepgrowth polymerization involves a reaction between. The mechanism requires that at least two different monomers participate in the reaction. The monomer in stepgrowth polymerization will be consumed very quickly to dimer, trimer or oligomer. It is the third of these criteria that offers the most powerful insight into the nature of the polymerization process for this important class of materials. Third, the reaction responsible for the polymerization must. Imaging the polymerization of multivalent nanoparticles in. Interfacial polymerizations rely on reactions of diacid chlorides and active.
In this lesson, learn about the process of polymerization. The reaction can be carried out in solution, in bulk melt, or in solid state. Figure 41 molecular mass distributions in step growth polymerization. Jan 01, 2007 an understanding of processes occurring in the polymerization reactor is therefore crucial to achieving efficient, consistent, safe and environmentally friendly production of polymeric materials. Step growth polymerization is also used for preparing a class of adhesives and amorphous solids called epoxy resins. Explore the two major types, common polymers, and some of the chemistry involved with this biologically and commercially important.
In a stepgrowth polymerization, the molecular weight of the polymer chain builds up slowly and there is only one reaction mechanism for the formation of polymer. Compared to chaingrowth polymerization, where the production of the growing chaingrowth is based on the reaction between polymer with active center and monomer, stepgrowth polymerization doesnt have initiator or termination. Introduction polymerization kinetics and modeling industrial step. In a stepgrowth polymerization, the molecular weight of the polymer chain builds. Stepgrowth polymerization, or condensation polymerization, is commonly employed to produce polyesters and nylons. Viscosity increases as conversion increases, making heat removal and processing more difficult. Polymer reaction engineering provides the link between the fundamentals of polymerization kinetics and polymer microstructure achieved in the reactor. A detailed discussion of several important step growth polymeriz ations follows in the next five chapters.
Simulation studies of stepgrowth polymerization, e. Differences between step growth polymerization and chain growth polymerization step growth chain growth growth throughout matrix rapid loss of monomer early in the reaction similar steps repeated throughout reaction process average molecular weight increases slowly at low conversion and high extents of reaction are. The literature in polymerization reaction engineering has bloomed sufficiently in the last several years to justify our attempt in putting together this book. The discussion in chapters 2 and 3 has been limited to the polymerization of bifunctional monomers, which give linear polymer chains. In stepgrowth polymerization, the molecular weight of the polymer chain builds up slowly and there is only one reaction mechanism for the formation of polymer. Stepgrowth polymerization forms polymers in a manner that is quite different from chaingrowth polymerization.
Rather than offer a comprehensive treatment of the entire field, thereby duplicating earlier texts as well as some ongoing bookwriting. The concepts here are explained in brief, for further details and clarification on the topic of polymerization reaction download byjus the learning app. There are several industrially important systems, e. Here the covalent bonding occurs by an s n 2 reaction between a nucleophile, usually an amine, and a terminal epoxide. Growth polymerization polymer reaction engineering wiley online library.
Synthesis of macromolecules by step growth polymerization 4. Reaction engineering of step growth polymerization santosh k. Stepgrowth polymerization forms polymers in a manner that is quite different from chain. Stepgrowth polymerization article about stepgrowth. The polymerization reaction occurs between the functional groups of molecules. A continuation order plan is available for this series. Welldefined aromatic polyamides, polyesters, and polyethers have been synthesized via substituent effectassisted chaingrowth condensation polymerization, in which the polymer propagating ends are more reactive than the monomers due to resonance or inductive effects between the functional groups of. Polymerization processes are categorized into two broad classes, according to their reaction mechanisms. Polymerization reactions are divided into two groups known as step reactions also called condensation reactions and chain reactions also known as addition reactions. Sep 18, 2019 step growth polymerization is also used for preparing a class of adhesives and amorphous solids called epoxy resins. Differences between stepgrowth polymerization and chaingrowth polymerization. The distinct initiation, propagation, and termination steps of chain growth polymerization are meaningless in step growth polymerization. To be successful in this field, a chemical engineer needs to understand a few principles beyond the basics of reaction engineering. The growth of np chains was described by the kinetics and statistics of stepgrowth polymerization 2426, which, for a particular time, allowed the prediction of the aggregation number and the size distribution of np ensembles, similar to the degree of polymerization and polydispersity index pdi of polymers, respectively.
R t decreases at high conversion due to the trommsdorf effect, making the reaction hard to control. Used for free radical polymerization ps, pmma and some step growth condensation polymerizations. Reaction engineering of step growth polymerization. Apr 21, 2017 college level organic chemistry 2 chapter 26 including closed captioned video. An example is the polymerization reaction involving terephthalic acid and ethylene glycol, both of which are bifunctional. Growth products, processes and modeling summary step. The present paper aimed at presenting some important stateofart problems on polymerization reaction engineering, and discussing, through some selected examples, on future directions and. Polymerization, any process in which relatively small molecules, called monomers, combine chemically to produce a very large chainlike or network molecule, called a polymer. Professor of chemical engineering, institute for polymer materials polymat, the university of the basque country, spain search for more papers by this author first published. In step growth polymerization, the molecular weight of the polymer chain builds up slowly and there is only one reaction mechanism for the formation of polymer. Step growth polymerization and condensation polymerization are two different concepts, not always identical. Dynamic networks that drive the process of irreversible step. Growth polymerization polymer reaction engineering.
Many polymers with real world applications are formed as a result of stepgrowth polymerisation. B reaction is that used to make cocacola bottles i. In a step reaction polymerization reaction, sometimes called condensation polymerization, the polymer chains grow by reactions that occur between two molecular species. 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. We report on the marked similarity between the selfassembly of metal nanoparticles and reaction controlled step growth polymerization. Stepgrowth polymerization process modeling and product. We shall sometimes use the terms stepgrowth and condensation polymers as synonyms, although stepgrowth polymerization. Growth proceeds by a stepwise 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.
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