Nylon-6,6 is a synthetic polyamide made from two monomers: hexane-1,6-diamine (a diamine) and hexanedioic acid (a dicarboxylic acid). Explain how nylon-6,6 is formed from these monomers, including the type of polymerisation involved, the bond formed between monomers, and the small molecule produced.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Nylon-6,6 is a widely used synthetic polymer found in clothing, ropes and engineering components. It belongs to the polyamide family of polymers.
Model answer (5 marks)
Nylon‑6,6 is produced by a condensation polymerisation.
1. The –NH₂ group of hexane‑1,6‑diamine reacts with the –COOH group of hexanedioic acid.
2. An amide bond (–CO–NH–) is formed, giving a peptide‑type linkage.
3. Water is eliminated as the small molecule in each step.
4. Because both monomers are difunctional, the reaction can continue from both ends, forming a long polymer chain.
1. The –NH₂ group of hexane‑1,6‑diamine reacts with the –COOH group of hexanedioic acid.
2. An amide bond (–CO–NH–) is formed, giving a peptide‑type linkage.
3. Water is eliminated as the small molecule in each step.
4. Because both monomers are difunctional, the reaction can continue from both ends, forming a long polymer chain.
Examiner tips
- Use the word "condensation" and mention "water" as the by‑product.
- Show the amide linkage and the reacting functional groups.
- Explain that each monomer has two reactive ends so chain growth is possible.
Common mistakes
- Saying "addition polymerisation" instead of condensation.
- Forgetting to mention water as the small molecule.
- Not identifying the amide bond or the reacting groups.
Mark scheme (5 marks)
- The type of polymerisation is condensation polymerisation
- The amine group (–NH₂) of hexane-1,6-diamine reacts with the carboxylic acid group (–COOH) of hexanedioic acid
- An amide bond (peptide/–CO–NH– linkage) is formed between the two monomers
- Water is the small molecule eliminated/produced in each step
- Because each monomer is difunctional (has two reactive groups), the reaction continues along both ends, building a long polymer chain
Key terms in this question
diamine · dicarboxylic acid · polyamide
Related
- All Edexcel A-Level Chemistry (9CH0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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