What is step growth polymerisation ? Explain with an example.

Explanation

### Step-by-Step Solution:

**Step 1: Definition of Step Growth Polymerization**
Step growth polymerization is a type of polymerization where monomers react with each other in a stepwise manner to form larger molecules. In this process, the molecular mass of the resulting polymer is not necessarily the same as that of the starting monomers, and small molecules such as water or amines are often eliminated during the reaction.

**Step 2: Characteristics of Step Growth Polymerization**
- **Condensation Reaction**: This type of polymerization is often referred to as condensation polymerization because it involves the elimination of small molecules (like water) during the formation of the polymer.
- **Variable Molecular Mass**: The molecular mass of the repeating units in the polymer is generally different from that of the original monomers.
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