2.4.5—Addition polymers
- Syllabus
- First assessment 2025
- Objective
- 2.4.5
- Level
- SL
Addition Polymers
Addition polymerization forms a chain by opening the monomer C=C bond. The substituents remain attached to the backbone carbons and continuation bonds show the repeating unit extends.
Remove the double bond in the monomer, preserve every substituent, and draw bonds out of the repeating unit at both ends.
Propene forms the repeat unit [–CH₂–CH(CH₃)–]ₙ: open the C=C, keep CH₃ on the same backbone carbon and draw continuation bonds through the brackets. No small molecule is eliminated, so atom accounting should match the monomer exactly.
Drawing Addition-Polymer Repeating Units
Assessment in practice
Representative question
Question 1
[Maximum number: 2]
Styrene can undergo polymerization.
Draw the structure of the polymer chain. Show three repeating units and state the type of polymerization that occurs.
Type of polymerization:
correct structure
AND
continuation bonds shown
addition «polymerisation»
Accept either structure for the benzene ring.
Accept phenyl rings on either side of the polymer backbone
Models to Materials Summary
Retrieve the pathway: locate bonding contributions, connect them to material properties, distinguish alloy lattice disruption, and construct addition or condensation polymer repeating units from monomer evidence.
Check that the bonding description matches the material, the property explanation names the structural cause, and every polymer substituent, continuation bond, and released small molecule is represented.