# Terylene is a condensation polymer used to make clothing and plastic bottles. It is formed from benzene-1,4-dicarboxylic acid and ethane-1,2-diol. Explain how Terylene is formed and describe one structural feature that makes it a condensation polymer rather than an addition polymer.

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

> Terylene (also known as PET) is widely used in the textile and packaging industries. Unlike addition polymers such as poly(ethene), Terylene is produced by a condensation polymerisation reaction between two different monomer molecules.

## Mark scheme (5 marks)

1. Condensation polymerisation involves monomers joining together with the loss of a small molecule
2. The small molecule lost is water (or HCl in other condensation reactions, but here specifically water)
3. One monomer provides carboxylic acid (–COOH) functional groups and the other provides hydroxyl (–OH) functional groups
4. The two functional groups react to form an ester linkage / ester bond between the monomers
5. Unlike addition polymers, the repeat unit of Terylene contains atoms from two different monomer molecules / the repeat unit is smaller than the combined monomers because atoms are lost as water

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