We have come across many polymerization reactions but one of the most significant reactions among themĀ is copolymerization. Firstly, let us define a polymer and a monomer. The repeating units of a molecule which links together to form polymers is known as a monomer. On the other hand, a polymer is defined as a large molecule which is composed of different subunits or monomers. So, a polymer molecule is nothing but a large molecule which is also known as a macromolecule. This is an area where people generally get confused between the definitions of monomer and polymer, the only thing that should be kept in mind for avoiding any confusion is breaking of words. For example: polymer if broken down will result in poly + mer, as we all know that poly means many and mer means a unit, similarly with monomer mono + mer, mono means 1 and mer means unit.

Let us have a brief review on homopolymers and copolymers before moving on to the process of copolymerization.

A homopolymer is defined as a polymer which is obtained by linking together only similar types of molecules (or monomers), whereas a copolymer is obtained by linking two or more different types of monomers in the same chain. There are many techniques of polymerization such as condensation, polymerization and copolymerization.

When a mixture of more than one (or different) monomeric species is allowed to polymerize and form a copolymer , then we call this process as copolymerization. Example- Nylon 66 is a copolymer of hexamethylenediamine and adipic acid. There are four different types of copolymers existing today:

  • Alternating copolymers: The copolymers which have two units placed at alternating positions. For example, we place a unit X then Y, then X and then again Y and the chain goes on.


The above figure shows the arrangement of alternating copolymers.

  • Periodic copolymers: The units of both X and Y is arranged in a repetitive sequence. The arrangement is as shown below:


  • Statistical copolymers: The arrangement of polymers in this case follows a statistical rule. When the probability of finding a given monomer at a particular point is equal to the mole fraction of that monomer in the same chain, then the polymer is referred to as a random copolymer. It has the following arrangement:


  • Block copolymers: When two or more polymers are linked by homopolymers then they are called as block copolymers.

The above arrangement shows the structure of the block copolymers. At BYJU’s the mentor support team is always willing to help you, if you have any queries or curious to know the details of these concepts , then do not hesitate to call us.

Practise This Question

Select the correct option: What type of polymer is [CH2CH(C6H5]n?