Question 1

Can a single type of monomer undergo condensation polymerisation?

Accepted Answer

Yes, provided the monomer molecule contains two different functional groups that can react with each other. A classic example is an amino acid (containing $-NH_2$ and $-COOH$ groups) or a hydroxycarboxylic acid (containing $-OH$ and $-COOH$ groups).

Question 2

What is the difference between a synthetic polyamide like Nylon and a natural polypeptide like a protein?

Accepted Answer

Both contain amide linkages. The key difference is their origin and monomer composition. Polypeptides are natural polymers made in biological systems from the 20 common $\alpha$-amino acids. Synthetic polyamides, like Nylon, are man-made from monomers such as diamines and dicarboxylic acids, which are not typically amino acids.

Question 3

Why is addition polymerisation sometimes called 'chain-growth' and condensation 'step-growth'?

Accepted Answer

This describes how the polymer chains grow. In 'chain-growth' (addition), an active site (e.g., a radical) adds monomers one by one very rapidly, so long chains form quickly while much monomer is still unreacted. In 'step-growth' (condensation), any two molecules can react (monomer + monomer, dimer + monomer, dimer + dimer, etc.), so the average molecular mass of all molecules in the pot increases slowly and in steps.

Predicting the type of polymerisation

What you need to know

Monomer Clues: Addition or Condensation?