REVISION NOTES
IGCSE Edexcel Chemistry
4.8 Synthetic Polymers
4.8.1 Know that an addition polymer is formed by joining up many small molecules called monomers
ADDITION POLYMERS
- Addition polymer is formed when many small molecules join together
- The process is called addition polymerisation
- The small molecules are called monomers (like lego building blocks)
![](https://resource.studiaacademy.com/wp-content/uploads/2023/08/edexcel_igcse_chemistry_topic-28_synthetic-polymers_001_forming-of-addition-polymer-1.png)
4.8.2 Understand how to draw the repeat unit of an addition polymer, including poly(ethene), poly(propene), poly(chloroethene) and (poly)tetrafluoroethene
FORMATION OF POLYMERS
- Polymers are formed by joining many monomers with C=C bonds together
- One of the bonds in each C=C bonds breaks and forms a bond with the adjacent monomer (like holding hands together)
- Monomers can be a variety of compounds with C=C bonds
- E.g. ethene, propene, chloroethene and tetrafluoroethene
NAMING POLYMERS
- Prefix: poly–
- + name of the monomer
- E.g. propene → poly(propene)
![](https://resource.studiaacademy.com/wp-content/uploads/2023/08/edexcel_igcse_chemistry_topic-28_synthetic-polymers_002_monomer-to-repeat-unit-of-polymer-diagram-2.png)
4.8.3 Understand how to deduce the structure of a monomer from the repeat unit of an addition polymer and vice versa
DEDUCING POLYMER REPEAT UNIT FROM MONOMER
- Draw several monomers next to each other
- Remove one of the bonds in C=C
- New bonds are formed in between the monomers, connecting monomers together
DEDUCING MONOMER FROM POLYMER UNIT
- Find the repeating unit in the polymer
- Draw only one repeating unit
- Remove the connecting bonds
- Add a second bond between C and C to form C=C bond
![edexcel_igcse_chemistry_topic 28_synthetic polymers_003_monomer to repeat unit and repeat unit to monomer diagram](https://resource.studiaacademy.com/wp-content/uploads/2023/08/edexcel_igcse_chemistry_topic-28_synthetic-polymers_003_monomer-to-repeat-unit-and-repeat-unit-to-monomer-diagram-3.png)
4.8.4 Explain problems in the disposal of addition polymers, including:
- Their inertness and inability to biodegrade
- The production of toxic gases when they are burned.
PROBLEMS IN DISPOSAL OF ADDITION POLYMERS
1. Landfill
- Addition polymers are formed by joining many monomers together with strong C-C bonds
- As a result, addition polymers are unreactive and chemically inert
- Polymers do not easily biodegrade
2. Incineration
- If polymers are burned, toxic gases may be produced
- Complete combustion: carbon dioxide (greenhouse gas)
- Incomplete combustion: carbon monoxide (toxic gas that reduces the capacity of blood to carry oxygen)
- Burning polymers with chlorine (e.g. PVC): hydrogen chloride gas (toxic gas)
4.8.5C Know that condensation polymerisation, in which a dicarboxylic acid reacts with a diol, produces a polyester and water
CONDENSATION POLYMERS
- Recall: alcohol + carboxylic acid → ester + H2O
- Dicarboxylic acid: functional group -COOH is present on both ends of the compound
- Diol: functional group -OH is present on both ends of the compound
- Condensation (esterification) can occur on both ends of alcohol and carboxylic acid compounds, forming a long polymer
4.8.6C Understand how to write the structural and displayed formula of a polyester, showing the repeat unit, given the formulae of the monomers from which it is formed including the reaction of ethanedioic acid and ethanediol:
- There should be several ester functional groups (-COO-) present in the polymer as repeating units
![edexcel_igcse_chemistry_topic 28_synthetic polymers_004_condensation polymer formation diagram](https://resource.studiaacademy.com/wp-content/uploads/2023/08/edexcel_igcse_chemistry_topic-28_synthetic-polymers_004_condensation-polymer-formation-diagram-2.png)
4.8.7C Know that some polyesters, known as biopolyesters, are biodegradable
BIOPOLYESTERS
- Polyesters that are biodegradable are called biopolyesters