90 total
By the end of these notes, you should be able to:
A polymer is a very long molecule made by joining together many small molecules called monomers. Think of it like a chain — each link in the chain is one monomer.
There are two main types of polymerisation you need to know:
Knowing how to tell them apart — both from the monomer structure and from the polymer structure — is the core skill of this subtopic.
In addition polymerisation, monomers simply add onto each other to form a long chain. No atoms are lost during the reaction — every atom in the monomers ends up in the polymer.
The key feature to look for is a carbon–carbon double bond (C=C), also called an alkene group. When monomers have a C=C, they can undergo addition polymerisation.
During the reaction, the double bond opens up (breaks), and each carbon uses its spare bond to join to the next monomer. This repeats thousands of times to build a long chain.
If the monomer contains a C=C double bond → addition polymerisation.
| Monomer | Common Name of Polymer |
|---|---|
| Ethene (CH₂=CH₂) | Poly(ethene) — also called polythene |
| Chloroethene (CH₂=CHCl) | Poly(chloroethene) — also called PVC |
| Propene (CH₂=CHCH₃) | Poly(propene) — also called polypropylene |
| Phenylethene (CH₂=CHC₆H₅) | Poly(phenylethene) — also called polystyrene |
| Tetrafluoroethene (CF₂=CF₂) | Poly(tetrafluoroethene) — also called PTFE or Teflon |
The repeat unit (the section of the polymer that repeats over and over) looks exactly like the monomer but without the double bond. The two carbons that were doubly bonded now each use that spare bond to connect to the rest of the chain.
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