Addition polymerization an overview sciencedirect topics. Some rop can be considered as a chain polymerization addition of monomer to a growing chain end but many reactions are more complicated and involve, e. In this equation, p is the polymer while x represents degree of polymerization, means active center of chaingrowth polymerization, m is the monomer which will react with active center, l is a lowmolarmass byproduct obtained during chain propagation. It is a chain reaction and no byproduct is release.
In condensation polymerization, water is released as a result of bonding between monomers, when one monomer gives up a hydroxyl group and the other monomer gives up a hydrogen in the process. The mechanism shows the essential role played by the solvent during polymerization reaction and in imidization. As part of the forensic evidence needed for a conviction, it is necessary to prove that the carpet fibers in the suspects car. Condensation polymerization in condensation polymerization, a small portion of the monomer molecule is not incorporated in the final polymer. Objectives polymers national council of educational. They shared the nobel prize in chemistry in 1963 using zieglernatta catalysts to polymerize nonpolar monomers. Helfferich, in comprehensive chemical kinetics, 2001. Condensation polymers form more slowly than addition polymers, often requiring heat, and they are generally lower in molecular weight.
A polymerization reaction in which water or some other simple molecule is eliminated from two or more monomer molecules as they combine to form the polymer or crosslinks between polymer chains. They found that the strength of the bond between the transition metal and the growing chain influences the structure of the polybutadiene formed. Based on nuclear magnetic resonance nmr studies, a probable reaction mechanism was proposed for the condensation polymerization of pyromellitic dianhydride with aromatic diamines in aprotic solvent, n,n. The chain growthstep growth system categorizes polymers based on their mechanism. A wellknown example of a condensation reaction is the esterification of carboxylic. Step reactions require bifunctional or polyfunctional monomers, while chain reactions require the presence of an initiator. Difference between addition and condensation polymerization. The mechanism shows the essential role played by the solvent during polymerization. Claisen schmidt condensation mechanism pdf download.
Many polymers, both addition and condensation, are used as fibers the chief methods of spinning synthetic polymers into fibers are from melts or viscous solutions. Suspension polymerisation major advantages of suspension polymerisation. Condensation polymers with high molecular weight, such as polyesters and polyamides, are usually produced by a combination of melt polymerization and solidstate polymerization ssp processes. In more straightforward polymerizations, alkenes form polymers through relatively simple radical reactions. Polymerisation techniques polymerisation techniques used in the production of some commercial polymers. Condensation polymers were defined as polymeric molecules that may be converted by hydrolysis, or its equivalent, into monomers that differ from the structural units by one molecule of h2o, hc1, nh3, etc. Polycondensation condensation polymerization fundamentals. This can induce chain branching through the terminal double bond propagation reaction. The second condensation polymerization you will carry out is a reaction between phenol and formaldehyde to produce a polymer known as bakelite see mechanism at the top of the next page. In chain polymerization, only the monomer can attach to the growing chain. Condensation polymerization materials world modules.
The hydrolytic process 5 consists of the reac tions illustrated in table 1. Pdf on jan 17, 2018, abdelaziz nasr moawed bakr elhoshoudy and others published emulsion polymerization mechanism find, read and cite all the research you need on researchgate. Carothers in his early work on the preparation of polyesters and polyamides to distinguish this class of polymers from vinyl polymers made by addition reactions. Condensation polymerization condensation polymerization is a form of a stepgrowth polymerization where smaller molecules or monomers react with each other to form larger structural units usually polymers. Linear polymers are produced from bifunctional monomers, i.
Mechanism of addition polymerization sem1 0 comments polymerization is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or threedimensional networks. Condensation polymerization definition of condensation. The coordination polymerization is invented by two italian scientists. Condensation polymers form from the step growth polymerization. The type of polymers that result from a condensation polymerization depends on the monomers. Condensation polymerization definition is polymerization in which a single molecule is eliminated distinguished from addition polymerization. Condensation polymers were defined as polymeric molecules that may be converted by hydrolysis, or its equivalent, into monomers that differ from the structural units by one. The tensile strength, stiffness, and dimensional stability. Addition polymerization results in homochain polymers whereas condensation polymerization results in hetrochain polymers. Many of the engineering thermoplastics belong to a polymer family derived from step growth polymerization, and more specifically, from condensation polymerization. The term condensation polymers was introduced by w. 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.
Coordination polymerization is another variant of chaingrowth polymerization. The main difference between addition and condensation polymerization is that in addition polymerization the polymers are formed by the addition of monomers with no byproducts while in condensation polymerization polymers are formed due to the condensation of two different monomers resulting in the formation of small molecules such as hcl, water, ammonia, etc. His research group works towards exploring new strategies to develop polymers that can selfsegregate, fold, and organize into sub10 nm size microphase separated. Both the aldol reaction and condensation are reversible. Mechanisms in postcondensation polymerization in the solid state. Condensation polymerization article about condensation. General article condensation polymerization s ramakrishnan s ramakrishnan is a professor in the department of inorganic and physical chemistry at the indian institute of science. Polyester prepolymers with relatively low molecular weight evidenced by a relatively low intrinsic viscosity, or iv are produced in a melt. Coordination polymerization an overview sciencedirect.
The condensation polymerization produces low molecular weight polymers as its end products, and they are biodegradable and easy to recycle compared to addition polymers. Condensation polymerizations, as the name suggests, utilizes bondforming reactions that generate a small molecule condensate, which often needs to be continuously removed to facilitate the formation of the polymer. Aqueous suspension poly merization is considered as bulk polymerization in droplets. The polymers usually formed by this mechanism have two functional groups, where functionality is defined as the average number of reacting groups per reacting molecule. Dna, proteins, carbohydrates methods for making polymers addition polymerization and condensation polymerization addition polymerization. This is the process through which amono acids link up to form proteins.
The type of polymers that result from a condensation polymerization depends. Condensation polymerization of pyromellitic dianhydride. Polyesters, polyamides and polyolefins are usually spun from melts, provided the tm is not too high. The polymerization is obtained with a broad molecular weight distribution due to the high viscosity and lack of good heat transfer. You also know from part 6 that a carboxylic acid and an amine can form an amide linkage, jand a carboxylic acid and an alcohol can form an ester linkage. Polymerization there are two basic reaction schemes that are of commercial interest for the polymerization of cap rolactam. Direct condensation polymerization of lactic acid soo hyun kim division of polymers, korea institute of science and technology, p.
Condensation polymerization on the other hand is a process in which the reaction takes place with a release of a byproduct like water, alcohol, etc. Condensation polymerization is a form of stepgrowth polymerization. Condensation polymerization, preparation of nylon 610 scenario. Bakelund performed this synthesis at the beginning of the twentieth century, producing the first synthetic polymer. In aldol reactions between two molecules of the same aldehyde are generally quite successful, since the equilibrium lies far to the right, and the yields are very high. Common condensation polymers include polyamides, polyacetals, and proteins. Examples of resins so made are alkyds, phenolformaldehyde and ureaformaldehyde, polyesters, polyamides, acetals, and polyphenylene oxide. The most significant difference is that in addition polymers there is no loss of atom. Sep 18, 2019 condensation polymers form more slowly than addition polymers, often requiring heat, and they are generally lower in molecular weight. The terminal functional groups on a chain remain active, so that groups of shorter chains combine into longer chains in the late stages of polymerization. It cannot be used to make condensation polymers or for ionic or zieglernatta polymerisations anything which reacts with water.
In chemical compounds, polymerization can occur via a variety of reaction mechanisms that vary in complexity due to the functional groups present in the reactants and their inherent steric effects. Some poly mers, like poly vinyl chloride or polyacrylonitrile, are insoluble in the monomers and precipitate during bulk polymerization. The mechanism of condensation polymerization you know that monomers that are joined by condensation polymerization have two functional groups. As we noted before, the two main types of polymerization are chain and step polymerization. The mechanism of the polymerization stepwise or chain reaction. In addition polymerization, two or more molecules of monomers attach together to form a polymer. 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.
Polymerisation general a process in which small molecules called monomers join together into large molecules consisting of repeating units. The addition and condensation polymers are nowadays also referred as chain growth polymers and step growth polymers depending on the type of polymerisation mechanism they undergo during their formation. Condensation polymers are formed by polycondensation, when the polymer is formed by condensation reactions between species of all degrees of polymerization, or by condensative chain polymerization, when the polymer is formed by sequential addition by condensation reaction of monomers to an active site in a chain reaction. A wellknown example of a condensation reaction is the esterification of carboxylic acids with alcohols. There is an abundance of kinetic information available in the literature on this polymerization mechanism 610. Stepgrowth polymerscondensation polymers chemistry. Polymerization kinetics step growth slow can use statistical methods as well as kinetics to describe mol.
The addition reaction may occur by way of radical, cationic, or anionic intermediates. The monomers are held together by a certain kind of bond such as an amide bond and a molecule is eliminatedin the process such as a water molecule. Many naturally occurring and some synthetic polymers are produced by stepgrowth polymerization, e. For the love of physics walter lewin may 16, 2011 duration. Pdf emulsion polymerization mechanism researchgate. We shall sometimes use the terms stepgrowth and condensation polymers as synonyms, although stepgrowth polymerization. In these types of polymerization reactions, a low molecular weight species, frequently water or an alcohol, is eliminated for each mainchain linkage. For reducing the disadvantages of bulk polymerization, the process can be carried out in a solution. Basecatalyzed aldol reactions in aqueous base, acetaldehyde undergoes a reaction called the aldol addition. Addition polymerization is the successive addition of alkene monomers to one another.
Claisen schmidt condensation mechanism pdf download download. Polymerization reactions are divided into two groups known as step reactions also called condensation reactions and chain reactions also known as addition reactions. Here when molecules of monomers react to form a bond they replace certain molecules. Small molecules react with each other to form larger structural units while releasing smaller molecules as a byproduct, such as water or methanol. Condensation polymerization definition, see under polymerization def 2. The kinetic chain starts with addition of monomer to a metal complex, propagation is by successive insertion of monomer at the metal, and termination occurs when the metal complex separates from the polymer. Addition and condensation polymerization are the two major processes of producing a polymer compound. First, the copolymer can be synthesized using mild conditions via cationic polymerization instead of high temperature melt condensation polymerization. But in condensation reaction, there is a loss of a molecule of water, ammonia etc as a byproduct. There are many forms of polymerization and different systems exist to categorize them. Condensation polymerization and polymerization mechanisms. Introduction to condensation polymerisation youtube.
The polymerisation reaction in which the polymer is formed by the condensation of two or more monomer is called condensation polymerisation. A condensation polymerization is a form of stepgrowth polymerization. Summary addition polymerization vs condensation polymerization. Condensation polymerisation or step growth polymerisation. In this article, i shall describe some of the essential principles of condensation polymerizations or more appropriately called. In freeradical polymerization in bulk, solution, and aqueous suspension the initiator is dissolved in the monomer. Coordination polymerization an overview sciencedirect topics. The initiation mechanism for cationic polymerization of cyclic ethers. The company you work for, specialty polymers corporation, has just been awarded a government contract to develop a polymer formulation for an injection molded connector to be used in a new military jet engine. In condensation polymerization, molecules of monomer andor lower molecular weight polymers chemically combine, producing longer chains that are much higher in molecular weight.
Condensation polymerization get full description along. Your mechanism should show why two equivalents of naoh must be used. On the other hand, in condensation polymerization, a part of the monomers is eliminated when the monomer becomes a part of the polymer. Other articles where condensation polymerization is discussed. The two most important stepgrowth polymerizations are condensation and addition polymerization. Difference between addition polymerization and condensation. The investigation of a famous murder case, in which the body was wrapped in a carpet, led to a suspect whose car trunk contained a few carpet fibers. Usually, for chaingrowth polymerization, there is no byproduct formed. All molecules present monomer, oligomer, polymer can react with any other molecule. Polycondensation condensation polymerization stoyko fakirov the university of auckland, department of mechanical engineering, private bag 92019, auckland, 1142 new zealand. Nov 15, 2015 for the love of physics walter lewin may 16, 2011 duration. Condensation polymerization is a reaction that joins two functional groups such as an alcohol and a carboxylic acid and forms a second small molecule such as water.