Question

Explain the difference between chain growth and step growth polymerisation.

Answer 1

	Chain Growth Polymerisation	Step Growth Polymerisation
I.	In this type of polymerisation, the monomers having one or more double bonds undergo repeated addition in presence of an initiator (generally peroxides) to form a chain of polymer.	In this type of polymerisation two different types of monomer units undergo a series of condensation reactions with the elimination of small molecules like water, $\mathrm{HCl}, \mathrm{NH}_3$ or alcohol.
II.	The rate of the reaction is fast and polymer is formed rapidly.	Rate of the reaction is slow and comparatively much more time is required for polymerisation.
III.	Example : Formation of polythene from ethylene molecules.	Example : Formation of nylon- 6,6 from the molecules of hexa-methylenediamine and adipic acid.