Condensation Polymers
Recognise nylon and Terylene from partial chains, distinguish amide and ester linkages, and connect man-made fibres to their uses.
On this page
The atoms joining two carbon-containing sections help you recognise a polymer family. Find C=O first, then look at the atom bonded beside it: N identifies an amide linkage, while O identifies an ester linkage.
Join at two functional groups
In the simple linear condensation polymers studied here, monomers have two functional groups so they can join at both ends. Each linkage-forming reaction also produces a small molecule, commonly water. A monomer with only one suitable functional group could attach at one end but could not keep extending this kind of chain at both ends.
The two functional groups may be on two different monomer types: for example, a diol has two alcohol OH groups and a dicarboxylic acid has two COOH groups. These can make a polyester. Details of nylon and Terylene manufacture and polymerisation mechanisms are outside this lesson; read their partial chains and linkages.
Read a partial structure
The labelled boxes below stand for carbon-containing sections of the chain. Their internal bonds are omitted so the linkages between sections are easier to see. They are neither individual atoms nor empty spaces. Follow the actual bonds from one section to the next, including the C=O bonds drawn above the chain.
Swipe or scroll sideways to inspect the complete overview.
Nylon and amide linkages
Nylon is a polyamide, with repeated amide linkages, -C(= O)-NH⁻. In a partial chain, locate the carbon double-bonded to O, then the N bonded directly to that carbon. In the nylon structure shown, each N also bonds to H and the next carbon-containing section.
The group -CONH⁻ is condensed notation for that connection. C=O must still be present: the O is not simply another atom along the backbone. Nylon fibres are used in fishing line, parachutes and clothing, where strong, light fibres are useful.
Terylene and ester linkages
Terylene is a polyester, with repeated ester linkages, -C(= O)-O⁻. Locate C=O and the O single-bonded to the same carbon; that O connects to the next carbon-containing section. This is the same ester linkage developed in Esters: Formation and Naming, repeated along a polymer chain.
Terylene fibres are used in clothing, curtain materials and sleeping-bag fillings. Suitable fibres can be durable and resist creasing; a loose fibre filling can trap air for insulation. Explain the relevant material property rather than assuming that every polyester product has the same properties.
Compare the studied polymerisations
| Feature | Alkene addition polymerisation | Condensation examples here |
|---|---|---|
| Starting molecules | Alkene monomers with C=C | Monomers with two suitable functional groups |
| Chain connection | C=C becomes C–C; units join by new C–C bonds | Repeated amide linkages in nylon or ester linkages in Terylene |
| Other product | None | A small molecule, commonly water |
| Examples | Poly(ethene), poly(propene) | Nylon, Terylene |
Do not classify from the word “polymer” alone. Use the given monomers, repeated connections and byproducts together. An amide linkage identifies the polyamide family; there are polyamides besides the particular nylon example studied here. Likewise, Terylene is one polyester, not the name of every polyester.
Use the linkage as evidence
Common misconception 1
Classify the polymerisation type
Learner claim
Use the linkage as evidence
View solution step by step
Inspect the linkage
Method
Find the repeated -CO-NH⁻ connection.Reason
This is an amide linkage.Working
Amide linkage → polyamide.Identify the example within the given pair
Method
Classify it as condensation polymerisation and identify nylon.Reason
Nylon is the required polyamide example.Working
Condensation polymer; polyamide; nylon.
Examiner practice 2
Read nylon and Terylene structures
Examination question
Match each partial structure to its linkage
View solution step by step
Identify structure A
2 marksMethod
Name nylon and its amide linkage.Reason
Nylon is a polyamide, so its chain contains -CO-NH⁻ connections.Working
A: nylon; amide linkage, -CONH⁻.Identify structure B
2 marksMethod
Name Terylene and its ester linkage.Reason
Terylene is a polyester, so its chain contains -CO-O⁻ connections.Working
B: Terylene; ester linkage, -COO⁻.
Self-mark with the mark scheme
Compare your response with each mark point. Select a point only when your response contains that evidence.
Self-mark both polymer identities and both linkage names.
Try without prompts
Mind stretcher 1: The chain is drawn the other way roundExtension
Two partial chains are ...-NH-C(= O)-A-C(= O)-NH-B-... and ...-O-C(= O)-A-C(= O)-O-B-..., where A and B are carbon-containing sections. Identify each polymer family and explain why reading left to right or right to left does not change your classification. Which would represent nylon, and which Terylene, if those are the two possibilities?
Show answer
The first is a polyamide and would be nylon within that pair: N bonds directly to a carbonyl carbon, giving an amide linkage. The second is a polyester and would be Terylene: O bonds directly to the carbonyl carbon and the next section, giving an ester linkage. Reversing the drawing changes the order in which symbols are read but keeps the same bonds and atoms connected.
Carry the structure forward
Read C=O together with the neighbouring N or O to identify the linkage. Carbon-containing sections and linkages can both differ between polymers. Next, Plastic Waste and Recycling uses these structural differences to explain why melting, cracking and polyester hydrolysis do different jobs.
Practise and check
Use the Organic Chemistry topic check to practise and check your understanding.
Syllabus and review details
- SEC G3 Pure Chemistry 2027 · 2027
Content structure and subject content, PDF pages 9–24
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