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The monomer molecules can be identical. Many thousands of monomer units are commonly included in a single molecule of a polymer. Polymerization differs from other processes, such as crystallization, in which huge numbers of molecules gather under the influence of a force.

Monomers react to generate polymers without producing by-products during polymerization. In most circumstances, additional polymerizations are carried out in the presence of catalysts, which in some cases exercise control over structural elements that have a significant impact on the polymer’s properties.

What Is Condensation Polymerization?

Condensation polymers are polymers that are generated through condensation processes. Condensation polymer monomers must have two functional groups in order for each monomer to link up with two other monomers. Step-growth polymerization is another common term for polymerization. There are a few exceptions that must be taken into account. Some compounds’ molecules react like condensation polymerization, yet they follow the chain growth pattern seen in added polymerization in some cases. Condensation reactions include the esterification of carboxylic acids with alcohols.

The reaction between a dibasic acid and a glycol is a classic step-growth condensation, as shown below:

 

HOOC–(CH2)n–COOH + HO–(CH2)m–OH ⟶ HOOC–(CH2)n–COO–(CH2)m–OH + H2O HOOC–(CH2)n–COO–(CH2)m–OH + H2O

Polyester is the name given to the resulting polymer. Because water is reactive with ester bonds and can reverse the reaction, it is continuously removed from the reaction system.

Condensation Polymerization Characteristics

  • One or two functional groups should be present in the molecules (like alcohol, amine, or carboxylic acid groups).
  • The reaction takes place between two functional groups or monomers that are similar or different. It can happen between a dimer and an oligomer, a monomer, and a compound, or a series and another polymer chain.
  • Ones of different sizes can sometimes combine to generate larger molecules.
  • It takes into account the mixed properties of both molecules and functional groups.
  • When both functional groups are difunctional, the condensation result produces a linear polymer.
  • The polymer generated is a cross-linked polymer with a three-dimensional network when one of the functional groups is tri-functional or tetra-functional.
  • When monomers are combined with one reactive cluster, the average molecular weight drops. As a result, the overall average molecular mass and cross-link density are determined by the functionality of each monomer.

Examples of Condensation Polymerization

Nylon and Polyester are two of the most prevalent polymerization products.

Polyamide and water are the end products of the reaction between adipic acid monomer and hexamethylene diamine monomer.

Another type of condensation polymerization is the reaction between a dibasic acid and a glycol to produce polyester. Again, the by-product is water, which is carefully avoided.

Points to Remember

  1. Polymerization is a chemical phenomenon in which monomers join together to produce lengthy polymer chains.
  2. The process of condensation polymerization is a type of step-growth polymerization.
  3. Tiny molecules react with one another to produce larger structural units and release by-products such as water or methanol molecules in condensation polymerization.
  4. The condensation polymerization reaction occurs between two functional groups or monomers that are similar or distinct.

Conclusion

Polymerization is the process of combining two or more monomers to form a polymer through a series of chemical processes. This method can produce a variety of long polymer chains or three-dimensional structures. Condensation polymerization is one of the basic types of polymerization processes. The term “condensation polymerization” refers to the release of water molecules throughout the process, and it is called condensation polymerization because the final product form lacks some water molecules. Condensation polymerization is a step-growth process in which tiny monomers are joined by the release of water molecules, resulting in a bigger structure.