Structure of Polymers
Chemistry: Cambridge International GCSE Supplement, topic 11.8.9
Structure of Polymers
Addition polymers form when alkenes join by opening double bonds, creating repeating units. Condensation polymers, like polyamides and polyesters, form by removing small molecules.
Addition polymers
- Polymers are made by joining alkenes.
- Students deduce the repeat unit of an addition polymer from an alkene.
- The alkene's double bond opens to form a chain.
- Example: Ethene forms poly(ethene) by repeating –CH2–CH2– units.
- Understand vice versa: deduce alkene from polymer repeat units.
Condensation polymers overview
- Condensation polymers are formed by removing small molecules.
- Condensation polymers form from two types of monomers.
- Two main types are polyamides and polyesters.
Polyamides from dicarboxylic acid and diamine
- Polyamides form from dicarboxylic acid and diamine monomers.
- This creates a polymer with amide (–CONH–) links.
- Example: Nylon, a polyamide, forms from hexanedioic acid + 1,6-diaminohexane.
Polyesters from dicarboxylic acid and diol
- Polyesters form from dicarboxylic acid and diol.
- Repeating units contain ester bonds (–COO–) linking monomers.
- Example: PET (polyethylene terephthalate) forms from benzene-1,4-dicarboxylic acid + ethane-1,2-diol.
Test yourself on Structure of Polymers
What happens to the double bond of an alkene during the formation of an addition polymer?