Nylon
Summary: Nylon is a synthetic condensation polymer (polyamide) formed from a dicarboxylic acid and a diamine. Water is eliminated with each amide bond formed. Used for clothing, ropes, parachutes, and fishing lines due to its high strength and elasticity. Tags: igcse chemistry organic-chem polymers condensation-polymer Created: 2026-07-14 Last Updated: 2026-07-23
What Is Nylon?
Nylon is a synthetic polyamide — a condensation polymer formed by the reaction between:
- A dicarboxylic acid (molecule with two —COOH groups)
- A diamine (molecule with two —NH₂ groups)
Each time the monomers link, a molecule of water (H₂O) is eliminated. The polymer chain is held together by amide linkages (—CONH—), the same type of bond found in proteins.
Formation of Nylon-6,6
The most common nylon is nylon-6,6, made from:
| Monomer | Formula | Type |
|---|---|---|
| Hexane-1,6-dioic acid (adipic acid) | HOOC—(CH₂)₄—COOH | Dicarboxylic acid |
| 1,6-diaminohexane (hexamethylene diamine) | H₂N—(CH₂)₆—NH₂ | Diamine |
The Reaction
Each —COOH group reacts with an —NH₂ group:
n HOOC—(CH₂)₄—COOH + n H₂N—(CH₂)₆—NH₂ → —[OC—(CH₂)₄—CONH—(CH₂)₆—NH]—ₙ + 2n H₂O
The repeating unit contains an amide linkage (—CONH—), which is why nylon is called a polyamide.
Repeating Unit
O O H H
‖ ‖ | |
—[—C—(CH₂)₄—C—N—(CH₂)₆—N—]—ₙ
Properties
| Property | Description | Reason |
|---|---|---|
| Strong | High tensile strength | Strong intermolecular hydrogen bonds between amide groups on adjacent chains |
| Elastic | Stretches and returns to shape | Chains can extend and recoil |
| Lightweight | Low density | Organic polymer |
| Abrasion resistant | Does not wear down easily | Strong covalent bonds in backbone |
| Water resistant | Does not absorb much water | Non-polar (CH₂)ₙ segments |
| Thermoplastic | Softens when heated | Can be melted and remoulded |
| Dyeable | Can be coloured | Amide groups accept dye molecules |
Uses of Nylon
| Use | Property Exploited |
|---|---|
| Clothing (shirts, sportswear, hosiery) | Strong, lightweight, elastic, dyeable |
| Ropes and cords | High tensile strength, abrasion resistant |
| Parachutes | Lightweight, very strong, tear resistant |
| Fishing lines and nets | Strong, water resistant, does not rot |
| Tents and backpacks | Lightweight, durable, water resistant |
| Toothbrush bristles | Flexible, durable, abrasion resistant |
| Carpets | Wear-resistant, dyeable |
Nylon Rope Trick (Demonstration)
The nylon rope trick is a classic classroom demonstration of condensation polymerisation:
- Dissolve the diacid chloride (sebacoyl chloride) in an organic solvent (e.g. cyclohexane)
- Carefully layer this on top of an aqueous solution of 1,6-diaminohexane
- Nylon forms at the interface between the two layers
- Grab the nylon film with tweezers and pull — a continuous thread of nylon forms
- The nylon thread can be wound onto a glass rod continuously
This demonstrates that condensation polymerisation happens at room temperature and that the polymer forms at the interface where the two monomers meet.
Key Facts
- Nylon is a polyamide (contains —CONH— amide linkages)
- Made by condensation polymerisation — water is eliminated
- Monomers: dicarboxylic acid + diamine
- Strong intermolecular hydrogen bonds between chains → high strength
- Thermoplastic — melts when heated, can be remoulded
- Synthetic — not found in nature (unlike protein polyamides)
- Nylon-6,6 is named because each monomer has 6 carbon atoms