Addition & Condensation Polymers
Section: 11. Organic Chemistry | Syllabus: Cambridge AS Level Physics 9702
Addition & Condensation Polymers There are two main types of polymerization reactions that form polymers: addition polymerization and condensation polymerization. They differ in how the monomers join together and whether a small molecule is eliminated.
Diagram Placeholder [COMPARISON DIAGRAM: Side-by-side visual showing: Left: Addition polymerization (monomers joining directly) Right: Condensation polymerization (monomers joining with water molecule leaving) Use arrows and simple shapes to illustrate the difference] Addition Polymerization Addition Polymerization A polymerization reaction where unsaturated monomer molecules (containing C=C double bonds) add together to form a polymer.
No other product is formed - only the polymer. Key Features Monomers: Must have a C=C double bond (alkenes) Process: Double bond breaks and monomers join end-to-end Products: Only the polymer is formed (no small molecules eliminated) Conditions: High pressure, high temperature, catalyst Type of reaction: Addition reaction (similar to addition reactions of alkenes) Key Concept In addition polymerization, the polymer has the SAME empirical formula as the monomer.
For example, ethene (C₂H₄) forms poly(ethene) with repeating unit (C₂H₄)ₙ. Mechanism of Addition Polymerization Step 1: The C=C double bond breaks open Step 2: Carbon atoms form new single bonds with adjacent monomers Step 3: This continues in a chain reaction forming very long molecules Animation Placeholder [INTERACTIVE ANIMATION: Step-by-step animation showing: 1.
Ethene monomers with C=C double bonds highlighted 2. Double bonds breaking 3. Monomers linking together one by one 4. Growing polymer chain 5. Final poly(ethene) structure with repeating units Include play/pause controls and step-by-step buttons] Examples of Addition Polymers 1.
Poly(ethene) - Polythene Monomer: Ethene (ethylene) H H | | C = C | | H H Polymerization: n CH₂=CH₂ → -(CH₂-CH₂)ₙ- Polymer structure (repeating unit): H H | | -( C - C )- | | n H H Uses: Plastic bags, bottles, packaging, pipes Diagram Placeholder [DIAGRAM: Show 4-5 ethene molecules with double bonds, then arrow, then the same molecules joined in a chain with single bonds.
Highlight the repeating unit in brackets.] 2. Poly(propene) - Polypropylene Monomer: Propene H H | | C = C | | H CH₃ Polymerization: n CH₃CH=CH₂ → -(CH₂-CH(CH₃))ₙ- Polymer structure (repeating unit): H H | | -( C - C )- | | n H CH₃ Uses: Ropes, carpets, crates, thermal clothing 3.
Poly(chloroethene) - PVC Monomer: Chloroethene (vinyl chloride) H H | | C = C | | H Cl Polymerization: n CH₂=CHCl → -(CH₂-CHCl)ₙ- Polymer structure (repeating unit): H H | | -( C - C )- | | n H Cl Uses: Window frames, pipes, electrical insulation, waterproof clothing 4.
Poly(tetrafluoroethene) - PTFE (Teflon) Monomer: Tetrafluoroethene F F | | C = C | | F F Polymerization: n CF₂=CF₂ → -(CF₂-CF₂)ₙ- Uses: Non-stick cookware, waterproof clothing, bearings Interactive Placeholder [INTERACTIVE: Build-a-Polymer tool - students select a monomer from dropdown (ethene, propene, chloroethene, styrene) and the tool shows: - Monomer structure - Arrow showing polymerization - Resulting polymer structure with repeating unit - Common uses and properties] Drawing Addition Polymers Method 1: Monomer to Polymer To draw the polymer from the monomer: Draw the monomer structure Remove the C=C double bond (replace with single bond) Add bonds extending from each carbon of the former double bond Put the repeating unit in brackets with subscript n Draw continuation bonds extending from the brackets Method 2: Polymer to Monomer To identify the monomer from the polymer: Find the repeating unit in brackets Identify the two carbon atoms in the backbone Add a C=C double bond between these carbons Remove the bonds extending beyond the unit Diagram Placeholder [STEP-BY-STEP DIAGRAM: Visual guide showing both methods: Top row: Converting ethene monomer to poly(ethene) with 5 steps Bottom row: Converting poly(propene) back to propene monomer with 4 steps Use colored highlights to show where bonds change] Condensation Polymerization Condensation Polymerization A polymerization reaction where monomers join together by eliminating a small molecule (usually water) during each bond formation.
Key Features Monomers: Must have TWO functional groups (one at each end) Process: Monomers join with loss of small molecule (H₂O, HCl, etc.) Products: Polymer + small molecule (usually water) Type of reaction: Condensation reaction (similar to esterification) Common linkages: Ester linkages (-COO-) or amide linkages (-CONH-) Key Concept Condensation polymers LOSE atoms during formation, so the polymer's empirical formula is different from the monomers.
Water or another small molecule is eliminated. Diagram Placeholder [DIAGRAM: Simple illustration showing two monomers with functional groups at each end, combining together with a water molecule being eliminated, forming a polymer link] Types of Condensation Polymers Polyesters Formed fr…
Interactive revision notes, videos and practice questions load below.