It is also called stepgrowth polymerization but there are some exceptions which react as condensation polymerization but follow the chain growth pattern. Step growth 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. The reaction can take place between two similar or different monomers. In the following example, the same bisphenol a intermediate used as a monomer for lexan serves as a. The synthetic processes of producing polymers from their monomers can be divided into step growth and chain growth polymerization.
Monomers are added one by one to the active site on the growing polymer. The number of growing polymer chains is restricted because the incoming monomers find it difficult to diffuse through the polymer layer at the interface without. In chapter 2 we saw that step growth polymerizations occur, one step at a time, through a series of relatively simple organic reactions. 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. Most chain growth polymers are formed from unsaturated hydrocarbons, with the unsaturation present as a double bond between carbon atoms table 1. The monomer in stepgrowth polymerization will be consumed very quickly to dimer, trimer or oligomer.
Stepgrowth polymerscondensation polymers chemistry. Stepgrowth polymerization forms polymers in a manner that is quite different from chaingrowth polymerization. The initiation, propagation, and termination steps are distinctly different. Stepgrowth polymerization is a polymerization process that involves a chemical reaction between multifunctional monomer molecules. Chaingrowth polymerizations require the presence of an initiating molecule that can be used to attach a monomer molecule at the beginning of the polymerization. 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. 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. Now let us look at an example for step growth polymerization for better understanding.
The distinction between stepgrowth polymerization and chaingrowth polymerization. Jun 27, 2017 polymerization is an important process in so many industries. For example, aminocaproic acid has an amine group at one end and a carboxyl group at the other. Pdf simultaneous chaingrowth and stepgrowth polymerization. During propagation, only monomers react to the active site at the end of the growing chain. Propagation it is the middle step in chain polymerization where successive monomers are attached to the growing chain. Welldefined aromatic polyamides, polyesters, and polyethers have been synthesized via substituent effectassisted chain growth 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 the. This chapter talks about different types of polymers obtained by step. Macromolecular chemistry university of texas at austin. Media in category chaingrowth polymerization the following 14 files are in this category, out of 14 total.
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. First, we examine how the degree of polymerization. In so doing we shall also have the opportunity to indicate some of the different types of chaingrowth systems. Chain growth polymerization an overview sciencedirect. The process results in the formation of chain and ultimately a polymer is formed. Media in category chain growth polymerization the following 14 files are in this category, out of 14 total.
Stepgrowth polymerization of inorganic nanoparticles science. Pdf reinvestigation of numerous ringopening polymerizations by means of malditof mass spectrometry has evidenced that cyclic polymers were formed. 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. There is very little change in the molecular mass throughout the. A rational strategy for the realization of chaingrowth. The combination of chain growth and step growth polymerizations was recently observed for the polymerization of 94vinylphenylcarbazole in the presence of phetclsncl 4 initiation system 50. Step growth polymerization typically takes place between monomers containing functional groups that react in high yield to form new functionalities. The two most important stepgrowth polymerizations are condensation and addition polymerization. These 3 types of polymerization share 3 common steps. Step growth polymerization, types of monomers, kinetics and equilibrium considerations, closed vs. Concentration of monomers decreases steadily throughout the reaction reaction is fast and polymer is formed at once. What are the major differences between stepgrowth and chain or addition polymerization.
Chaingrowth and stepgrowth polymerization are described in. Stepgrowth polymerization refers to a type of polymerization mechanism in which bifunctional. 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. 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. Stepgrowth polymerization forms polymers in a manner that is. Polymerization of isobutylene 2methylpropene by traces of strong acids is an example of cationic polymerization. Step growth polymerization p olymerization mechanism in which bifunctional or multifunctional monomers react to form first dimers, then trimers, longer oligomers and eventually long chain polymers. As stated in chapter 1, chaingrowth polymerizations take place in discrete steps.
Stepgrowth polymerization forms polymers in a manner that. Stepgrowth polymerization journal of chemical education. 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. The process of step growth polymerization is a little more complicated than chain growth polymerization. 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. Chain growth polymerization an overview sciencedirect topics. The two most important step growth polymerizations are condensation and addition polymerization. Chain growth polymerization is basically a threestage process, involving initiation of active molecules, their propagation and termination of the active. Jul 09, 2010 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.
It is the addition of monomers to an evergrowing chain. Chain growth polymerization proceeds by the formation of an active center of growth 8,9. An example is adipic acid that has two functional groups, but both are carboxylic acid groups. Oct 24, 2016 reported here is the simultaneous chain. Step growth polymerization is also used for preparing a class of adhesives and amorphous solids called epoxy resins. All molecules present monomer, oligomer, polymer can react with any other molecule. Chain growth polymerization is a process in which the high molecular weight polymer is formed early in the polymerization process and the polymer yield the percentage conversion of the monomer into the polymer gradually increases with time. Answer to what are the major differences between stepgrowth and chain or addition polymerization skip navigation. Polymerization is an important process in so many industries. A schematic representations of step growth upper and chain growth lower polymerizations.
Stepgrowth polymerization typically takes place between monomers containing functional groups that react in high yield to form new functionalities. One variety of stepgrowth polymerization is called condensation polymerization and the product a condensation polymer because the chemical reaction by which the monomer molecules bond is often a condensation reaction that. Feb 16, 2016 the process results in the formation of chain and ultimately a polymer is formed. Examples of such functional groups are carboxylic acids, which react with alcohols to form esters and with amines to form amides. Many naturally occurring and some synthetic polymers are produced by stepgrowth polymerization, e. 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.
In the propagation stage, the process of electron transfer and consequent motion of the active. Stepgrowth polymerization forms polymers in a manner that is quite different from chain growth polymerization. Converting step growth polymerization to chain growth. 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 distinct initiation, propagation, and termination steps of chain growth polymerization are meaningless in step growth polymerization. Chemistry of industrial polymers chemistry of industrial polymers stepgrowth polymerization.
Figure 41 molecular mass distributions in step growth polymerization. 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. Chemistry of industrial polymers chemistry of industrial polymers step growth polymerization. In so doing we shall also have the opportunity to indicate some of the different types of chain growth systems. Stepgrowth polymerization is also used for preparing a class of adhesives and amorphous solids called epoxy resins. Polymerization kinetics step growth slow can use statistical methods as well as kinetics to describe mol. A schematic representations of stepgrowth upper and chaingrowth lower polymerizations. The distinct initiation, propagation, and termination steps of chaingrowth polymerization are meaningless in stepgrowth polymerization. Converting step growth polymerization to chain growth free download as powerpoint presentation. Equilibrium step condensation polymerizations, interchange reactions. Monomer does not react with monomer and the different sized species such as dimer, trimer, and nmer do not react with each other. Mar, 20 applies the steadystate approximation to a chain growth polymerization to determine how the rate of reaction depends on initiator and monomer concentrations. Chain growth system the characteristic of a chain polymer is that polymer growth takes place by monomer reacting only with the reactive centers.
Growth polymerization handbook of polymer synthesis. Chain growth and step growth polymerization are described in. Polymer science submitted by 1st year 2nd semester group. In stepgrowth polymerization, propagation involves coupling of multiple combinations of monomers and oligomers of varying lengths. In a step growth polymerization, the molecular weight of the polymer chain builds up. Chain growth polymerization is basically a threestage process, involving initiation of active molecules, their propagation and termination of the active chain ends.
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. Two types of monomers can undergo stepgrowth polymerizations. 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. In a stepgrowth reaction, the growing chains may react with each other to form even longer chains. Chemistry of industrial polymers stepgrowth polymerization. The mechanism requires that at least two different monomers participate in the reaction. Stepgrowth polymerization an overview sciencedirect topics. 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. Here the covalent bonding occurs by an s n 2 reaction between a nucleophile, usually an amine, and a terminal epoxide. Chaingrowth polymerization is a process in which the high molecular weight polymer is formed early in the polymerization process and the polymer yield the percentage conversion of the monomer into the polymer gradually increases with time.
Equivalent terms are either chain polymerization or chain. Stepgrowth polymerization vs chain growth, to be covered in more detail later in the course, extent of reaction, numberaverage degree. The combination of chaingrowth and stepgrowth polymerizations was recently observed for the polymerization of 94vinylphenylcarbazole in the presence of phetclsncl 4. This process is similar to radical polymerization, as demonstrated by the following equations. Difference between chain growth and step growth polymerization. In chapter 2 we saw that stepgrowth polymerizations occur, one step at a time, through a series of relatively simple organic reactions. In step growth polymerization, propagation involves coupling of multiple combinations of monomers and oligomers of varying lengths. Stepgrowth polymerization of inorganic nanoparticles. The polymerization of unsaturated monomers typically involves a chain growth polymerization. Open systems kinetics of step growth polymerization chapter 2.
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