Condensation Polymerization: Characteristics, Polymerization, Addition Polymerization

Condensation Polymerization is a process in which polymers are formed by removing water or alcohol during polymerization. The final molecular weight of the polymer is controlled by the equilibrium concentration of water or alcohol in the molten polymer at the end polymerization. In this article, we will discuss Polymerization, Condensation Polymerization, its characteristics and Important Questions.

Keyterms: Condensation, Polymerization, Polymers, water, alcohol, Condensation Polymerization, Addition Polymerization, methanol

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Polymerization

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Polymerization is defined as a process in which monomers engage in a chemical reaction and form long polymer chains or three-dimensional networks. Polymerization typically happens via different reaction mechanisms which are full of factors just like the functional groups of the reacting compounds and their nonbonding interactions. There are mainly two types of polymerization- Condensation Polymerization and Addition Polymerization. 

Also Read: Molecular Orbital Theory Postulates

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Condensation Polymerization

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Condensation polymerization is a step-growth polymerization where tiny molecules react with each other to make larger structural units while releasing the by-products like water or methanol molecule. The by-products are usually known as condensate.

Polymerization is also generally mentioned as step-growth polymerization. There are few exceptions that require to be considered. There are instances where molecules of some substances react as condensation polymerization, however, they follow the chain growth pattern as seen in additional polymerization. The esterification of carboxylic acids with alcohols is a good example of a condensation reaction.

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Characteristics of Condensation Polymerization

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The main characteristics of Condensation Polymerization are:

• The molecules should have one or two functional groups (like alcohol, amine, or carboxylic acid groups). 
• The reaction takes place between two similar or different functional groups or monomers. It will occur between a dimer and oligomer, one monomer and one compound or between a series and another chain of polymers.
• Smaller molecules sometimes mix to form larger molecules.
• Mixed properties of both the molecules or functional groups are taken into consideration.
• A linear polymer is obtained because of the condensation product when both functional groups are difunctional.
• When one of the functional groups is tri-functional or tetra-functional, the polymer formed is a cross-linked polymer having a three-dimensional network.
• The average molecular weight decreases once monomers are added with one reactive cluster. Therefore, the functionality of every monomer determines the average relative molecular mass and cross-link density.

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Examples of Condensation Polymerization

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The most common example of products of polymerization is Nylon and Polyester.

When adipic acid monomer and hexamethylene diamine monomer reacts, then the final products obtained are polyamide and water.

The reaction between a dibasic acid and a glycol to form polyester is another form of condensation polymerization. The by-product here is again water which is keenly avoided.

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Addition Polymerization and Condensation Polymerization

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In addition polymerization, polymers are formed by adding monomers without by-products. In condensation polymerization, polymers are formed due to the condensation of many different monomers, which leads to the formation of small molecules. Few key differences between both are given below: 

• In Addition Polymerization monomers solely join at the active site of the chain. However, in condensation polymerization, any molecule can react with the other.
• In Addition Polymerization, there are three distinct steps. Initiation, propagation and finally termination. In condensation polymerization, there is no termination step. The end groups stay reactive through the complete method.
• Addition polymerization leads to homo-chain polymers whereas condensation polymerization leads to hetero-chain polymers.
• The most important distinction is that in addition to polymers there is no loss of atom. However, in a condensation reaction, there is a loss of a molecule of water, ammonia, etc. as a by-product.
• In addition polymerization, lewis acids and radical initiators are catalysts and in condensation polymerization, acid monomers catalyze the reactions. 

Read more: Concentration of Ore

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Things to Remember

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• The process in which monomers engage in a chemical reaction and form long polymer chains is called Polymerization.
• Condensation polymerization is a step-growth polymerization process.
• In condensation polymerization, tiny molecules react with each other to form larger structural units and release by-products like water or methanol molecules. 
• The condensation polymerization reaction takes place between two similar or different functional groups or monomers.

Also Read: Hybridization