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Repeat Unit of Poly(ethene)
- Poly(ethene) has a repeat unit formed by addition polymerisation from ethene monomers.
Addition Polymers
Key Characteristics
- Addition polymers are formed from alkene monomers with C=C bonds.
- One bond in the C=C breaks, allowing bonding with adjacent monomers.
- The polymer structure consists of single bonds between carbon atoms.
- Many addition polymers are derived from alkenes with additional groups like chlorine (as in
PVC) or hydroxyl (OH).
Naming Addition Polymers
- Named by adding “poly-” before the monomer’s name.
- Example: Poly(propene) from propene.
Deducing the Polymer from the Monomer
To draw a repeat unit:
1. Change the double bond in the monomer to a single bond in the repeat unit.
2. Add continuation bonds extending outside the brackets on each end.
3. Add a small n at the bottom right to indicate many repeat units.
4. Place groups in the same order around the bond as in the monomer.