# Polymers can be divided into two main types based on how they are formed: addition polymers and condensation polymers. Explain the differences between addition polymerisation and condensation polymerisation, including reference to the types of monomers used and any by-products formed.

> Edexcel A-Level Chemistry (9CH0) — 18.3 Polymers · Explain · 5 marks

## Mark scheme (5 marks)

1. Addition polymerisation involves monomers that contain a C=C double bond (alkenes/unsaturated monomers)
2. In addition polymerisation, the double bond opens/breaks and monomers join together to form a long chain with no other products
3. Condensation polymerisation involves monomers with two functional groups (e.g. –OH and –COOH, or diamine and dicarboxylic acid)
4. In condensation polymerisation, a small molecule by-product is released each time monomers join
5. Condensation polymers contain a repeat linkage group such as an ester linkage (in polyesters) or an amide linkage (in polyamides/nylon)

## Key terms

- [addition polymerisation](https://www.gradenine.co.uk/glossary/addition-polymerisation)
- [condensation polymerisation](https://www.gradenine.co.uk/glossary/condensation-polymerisation)
- [monomer](https://www.gradenine.co.uk/glossary/monomer)
- [by-product](https://www.gradenine.co.uk/glossary/by-product)

## Related

- [Revision notes for Edexcel A-Level Chemistry (9CH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/polymers-can-be-divided-into-two-018e0410) · Published by Druglandscape Ltd.