Nylon is a condensation polymer made from two different monomers. Explain how condensation polymerisation produces nylon, including the role of the functional groups on the monomers and what is produced alongside the polymer chain.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Nylon is a widely used synthetic polymer found in clothing, ropes and toothbrush bristles. It is formed by condensation polymerisation from monomers that each contain two functional groups.
Model answer (5 marks)
Monomers of nylon are diamine and diacid chloride (or diacid). Each monomer has two reactive functional groups – an –NH₂ group on the diamine and a –COCl (or –COOH) group on the diacid. During condensation polymerisation the –NH₂ of one monomer reacts with the –COCl of another, forming an amide bond (–CONH–) and releasing a small molecule – HCl (or H₂O if using –COOH). Repeating this step joins many monomers into a long chain, giving nylon. Because two different monomers are used, the repeating unit is not identical to the monomers themselves.
Examiner tips
- Show the two monomers and their functional groups, then describe the amide bond formation and the small molecule lost.
- Mention that the polymer is a long chain of amide linkages and emphasise the use of two different monomers.
Common mistakes
- Confusing addition polymerisation with condensation, or saying no small molecule is lost.
- Failing to identify the specific functional groups (e.g. using –OH instead of –COCl).
Mark scheme (5 marks)
- Monomers join together to form a long polymer chain
- Each monomer has two functional groups
- The functional groups on different monomers react with each other to form bonds
- A small molecule is lost / released during the reaction
- Unlike addition polymerisation, the monomer molecules are not all identical / two different types of monomer are used
Key terms in this question
condensation polymerisation · monomers · functional groups · polymer chain
Related
- All OCR A-Level Chemistry A (H432) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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