Molecules of ethene can polymerize with each other under the right conditions to form the polymer called polyethylene. In addition polymerization, monomers react to form a polymer without the formation of byproducts. The chain growth of addition polymerization is based addition reactions. Chaingrowth polymerizations require the presence of an initiating molecule that can be used to attach a monomer molecule at the beginning of the polymerization. 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. Heat generation is seldom a problem in smallscale laboratory reactions, but on a large industrial scale it can be dangerous, since heat causes an increase in the reaction rate, and faster reactions in. When the chain reaction is initiated and carried by negatively charged intermediates, the reaction is known as anionic polymerization.
A good example is the freeradical polymerization of styrene, which is initiated by a free radical r that reacts. Many naturally occurring and some synthetic polymers are produced by stepgrowth polymerization, e. Concepts polymers addition reactions chain reaction freeradical initiators materials student volunteers, 7 or more. Under most common conditions a polymer is produced that is a mixture of both of the above reactions. Preparation of polystyrene using two types of initiators submitted by. Addition and condensation polymerization processes. In addition polymerization, the monomers add to one another in such a way that the polymer contains all the atoms of the starting monomers. The coordination polymerization of alkene can be preceded either by monometallic mechanism or bimetallic mechanism depending on the catalyst. Propagation is the addition of a monomer molecule to a radical chain. Polymers are the primary components of all sorts of plastics and related compounds. A good example is the freeradical polymerization of styrene, which is initiated by a free radical r that reacts with styrene. The net rate of production of free radicals is zero so that the initiation and termination rates are equal.
Polymerization reactions such as that shown for eaminoca proic acid ab monomer or adipic acid aa monomer with hexamethylenediamine bb monomer can be written in the general forms, as follows. Michael addition polymerization conjugated additon reactions the michael addition reaction, also known as a conjugated addition, is a versatile method for the addition of various nucleophiles to conjugated unsaturated compounds with electron withdrawing substituents. Notice that the presence of a double bond in the resulting polymer provides the opportunity for a polymer with either cis double bonds or trans double bonds or a mixture. Polymerization reactions is called chaingrowth polymerization or addition polymerization. In addition polymerization, two or more molecules of monomers attach together to form a polymer. Small molecules react with each other to form larger structural units while releasing smaller molecules as a byproduct, such as water or methanol. The three steps of this reaction to focus on are how the reaction gets started initiation how the reaction keeps going propagation. Introduction description this is an excellent lab to introduce students to addition polymerization and to the concept of initiators. This represents a danger, for example during monomer transportation, since it may lead. The addition reaction may occur by way of radical, cationic, or anionic intermediates. The bond lines extending at the ends in the formula of the product indicate that the structure extends for many units in each direction. The freeradical polymerization of methyl methacrylate, acrylonitrile, and other polymer monomers can be accelerated by adding. Mechanism of addition polymerization free radicle reaction mechanism free radical mechanism of chain reaction involves 3 stages namely i. Addition polymerization an overview sciencedirect topics.
Chain growth polymers, which are often referred to as addition polymers, form via chain addition reactions. Chain reaction polymerization, sometimes called addition polymerization, requires an initiator to start the growth of the reaction. Polymerization formation of large polymers polymers organic compounds made up of smaller chains covalently bonded together. Ethylene molecules are joined together in long chains. Worksheet addition reactions the presence of electrons in alkenes allows addition reactions to take place. A condensation polymerization is a form of stepgrowth polymerization. The polymerization of unsaturated monomers typically involves a chain growth polymerization. Addition polymerization preparation of polymers introduction use this interactive classroom activity to teach students about the steps involved in the preparation of addition polymers via freeradical chain reactions. These processes can occur in the gaseous, liquid and sometimes in the solid phase of the monomer.
But in condensation reaction, there is a loss of a molecule of water, ammonia etc as a byproduct. Addition polymerization definition, see under polymerization def 2. The reaction to make polypropylene h 2 cchch 3 is illustrated in the middle reaction of the graphic. Pdf anionic disadvantages more difficult than many polymer techniques simple. There are two general types of polymerization reactions. Some polymers can be formed either by addition or condensation reactions. The under standing of the relationship between the molecular structure, the kinetics of the process, and the performance characteristics of the product enables. Based on the chemical reaction involved, polymerisation is divided into two groups known as addition polymerization and condensation polymerization. Polymerization, in polymer chemistry, is the process of reacting monomer molecules together in a chemical.
The polymer can be represented by showing the repeating ppt. Difference between addition polymerization and condensation. Type of initiators used in free radical polymerization. The double bond of alkene will undergo cis addition and coordinate with the empty orbital of titanium compound to form four. Addition polymers can also be made by chain reactions that proceed through intermediates that carry either a negative or positive charge. The two major types of polymerization are addition polymerization and condensation polymerization. Once a chain reaction gets started, it is able to keep itself going. There are many types of initiators which used in addition polymerization for starting this reaction. At that time we noted that these classifications could be based on the following. The plastics and rubber are examples of the most common polymers which are commonly used in both everyday life and in medical applications. In addition to synthetic polymers, such as, polyvinyl chloride, polystyrene, nylon. Anionic polymerization chain transfer to solvent ch 2 c. The stoichiometry of the polymerization reaction small molecule eliminated.
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. Addition polymerization differs from condensation polymerization, which does cogenerate a product, usually water. The addition polymerization reactions described above are usually exothermicthat is, they generate heat. And in condensation reactions, functional groups of two monomers react together releasing a small molecule to form a polymer. The largest family of polymers 3, vinyl polymers, are produced by chain polymerization reactions. Addition polymerization proceed through two types of mechanism. A wellknown example of a condensation reaction is the esterification of carboxylic.
Polymers are very different from the other kinds of organic molecules that you have seen so far. Other articles where addition polymerization is discussed. Interactive physical model for the preparation of addition polymers. Addition polymerization in this type of polymerisation, the molecules of the same monomer or diferent monomers add together on a large scale to form a polymer. Polymerization kinetics step growth slow can use statistical methods as well as kinetics to describe mol. Classification of polymerization reactions as additions or condensations be gan with. Bulk polymerization or mass polymerization is carried out by adding a soluble radical initiator to pure monomer in liquid state. Each individual unit monomer ex of polymers synthetic plastics, nylon, proteins, starch, cellulose 2 types of polymerization reactions addition polymerization joining of monomers of unsaturated compounds.
Addition polymerization results in homochain polymers whereas condensation polymerization results in hetrochain polymers. In addition to the conversion of the functional groups, the degree of poly. The two main types of polymerization are addition and condensation reactions. 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. Addition polymerization chemical reaction britannica. Chaingrowth polymerization is most commonly applied to vinyl monomers that is, monomers containing carboncarbon double bonds and to certain types of cyclic monomers that is, monomers in which the double bond is contained in ringshaped molecules. Addition polymerizations usually are carried out in the presence of catalysts, which in certain cases exert control over structural details that have important effects on the properties of the polymer.
Ammonia is an example of such a protic solvent and the reaction results in the formation of a negatively charged nh 2 ion, which can. Therefore, addition polymerization is the reaction between monomers with multiple bonds, where they join together to form saturated polymers. A reaction initiated by an anion, cation, or radical in which a large number of monomer units are added rapidly a chain reaction until terminated by some mechanism, forming a highmolecularweight polymer in a very short time. There is no lowmolarmass byproduct formed during polymerization. Difference between chain growth and step growth polymerization. In this type of polymerization, two molecules combine, causing the loss of a smaller molecule such as water, an alcohol or acid. We can diagrammatically represent this polymerization reaction with a.
Polymerization is a reaction process in which two or more monomers are bonded chemically to form large polymer chains or threedimensional networks. Addition polymerization is the successive addition of alkene monomers to one another. The process of monomer addition is a chain reaction. Termination schematic representation r free radical m unsaturated monomer introduction to polymers 20 21. Cationic polymerization some differences between cationic and anionic polymerization rates are faster for cationic 1 or more orders of magnitude faster than anionic or free radical is very reactive, difficult to control and stabilize c more transfer occurs. The main difference between chain growth polymerization and step growth polymerization is that the chain growth polymerization involves the growth a polymer chain at its ends whereas. The most significant difference is that in addition polymers there is no loss of atom.
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. In addition polymerization, electrons from a doublebond are used to form bonds between other. Polymer chemistry university of south carolina upstate. The polymerization reaction which involves joining of unsaturated monomers by breaking of. B reaction is that used to make cocacola bottles i. Arturo contreras, visiting scholar, center for chemical education, miami university, middletown, oh. The exact properties of polymers depends on a variety of chemical. This reaction was first discovered by arthur michael in 1887. The process of joining small molecules to form a large molecule is known as polymerization. Anshuman shrivastava, in introduction to plastics engineering, 2018. Step reactions require bifunctional or polyfunctional monomers, while chain reactions require the presence of an initiator.
Addition polymerization is a chain reaction, generally associated with the polymerization of ethene or vinyl type monomers, such as, ethene, propene, styrene. The addition of large amounts of dehp produce a very flexible plastic which is used in. Chemical engineering 160260 polymer science and engineering. The reaction is initiated by heating or exposing to radiation. In an addition, two molecules combine to form one product molecule. The polymer can be represented by showing the repeating unit with square brackets around it. This video is part of the flinn scientific best practices for teaching chemistry video series, a collection of over 125 hours. The reaction which leads to the formation of polymers from their respective monomers is called polymerization reaction. Addition polymerization download in this worksheet, we will practice defining an addition polymerization and determining the structure of an addition polymer from the monomer reactant.
A polymer is a macromolecule which consists of small molecular units that are repeated over and over again to form a long chain. May 11, 2020 chain reaction addition polymerization the polymerization can be represented by the reaction of a few monomer units. Polymerization by addition addition polymerization can be divided. 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.
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. These 3 types of polymerization share 3 common steps. The second type of polymerization reaction produces condensation polymers. Polymerization reactions are divided into two groups known as step reactions also called condensation reactions and chain reactions also known as addition reactions. The stepgrowth polymerization based on addition reaction during chain growth is defined as polyaddition.
Chain reaction addition polymerization the polymerization can be represented by the reaction of a few monomer units. Classification of polymerization reaction addition and. It is a chain reaction and no byproduct is release. Addition polymerization is also a type of previous definition. An addition polymer is a polymer formed by chain addition reactions between monomers that contain a double bond. Notice how every other carbon must have a chlorine attached. Addition and condensation polymers and polymerization. Addition polymerization takes place when the monomer molecule contains double carbon bonds, as in alkenes, or triple carbon bonds, as in alkynes. Addition polymers mechanism of addition polymerization.
The polymerization reaction kinetics of benzoxazine resins is described in this chapter. As the reaction proceeds the mixture becomes more viscous. Graphenebased electrochemical sensors for biomolecules, 2019. Notice that the polymer bonds are always through the carbons of the double bond. 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. Difference between addition and condensation polymerization. Olefinic or vinyl polymerizations invariably lead to addition polymers. We are talking about polymers but have you thought, what is a monomer. 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. Addition polymerization is the process of repeated addition. The formation of a polymer by addition polymerization is an example of a chain reaction. Polymerization is an important process in so many industries. This mode of formation contrasts sharply with that involved in typical addition polymerizations, which are characterized by the fact that the polymer molecules first. In addition polymerization all of the atoms of the monomer molecules become part of the polymer.786 1461 1343 1113 946 1358 1109 680 261 1353 1034 1538 275 1258 138 1464 1254 1282 692 677 303 180 1263 388 191 357 312 124 1196 663 740 912 698 1007 24 1139 588 198 57