Polymerisation

Summary: The process of joining many small monomer molecules together to form a long-chain polymer. Tags: igcse chemistry definition organic-chem Created: 2026-07-14 Last Updated: 2026-07-14

Polymerisation is the chemical process in which many small monomer molecules join together to form a long-chain polymer with repeating structural units, and it is fundamental to the production of plastics, synthetic fibres, and many biological macromolecules. In addition polymerisation, the carbon-carbon double bond of unsaturated monomers such as ethene opens up, allowing monomers to link together without the loss of any atoms, producing polymers like poly(ethene), poly(propene), and PVC. Condensation polymerisation, by contrast, involves monomers with two functional groups reacting together with the elimination of a small molecule such as water or hydrogen chloride, as seen in the formation of nylon (a polyamide) and PET (a polyester). Polymers have transformed modern life through applications ranging from plastic packaging and synthetic fabrics to biomedical implants and construction materials, though their environmental persistence has created significant waste management challenges that chemistry seeks to address through biodegradable and recyclable alternatives. In IGCSE exams, you must be able to identify the repeating unit from a given monomer structure, deduce the monomer from a polymer chain, and distinguish between addition and condensation polymers by whether a small molecule is eliminated during polymerisation.

Key term — IGCSE Chemistry (0620/0971) glossary.