Polymer is defined as very large molecules having high molecular mass (103 - 107 u). These are also known as macromolecules, which are formed by repeated structural units on a large scale. The repeated structural units on a large scale. The repeating structural units are derived from some simple and reactive molecules known as monomers and are linked to each other by covalent bonds. This process of formation of polymers from respective monomers is called polymerisation.