Identify the repeat units and/or linkages in addition polymers and in condensation polymers 🧪.
In addition polymerisation, the double bond of the monomer opens and the monomers link together without losing any atoms.
Think of it as a line of dominoes falling one after another – each domino (monomer) adds to the chain, but nothing is removed. 🔄
| Polymer | Monomer | Repeat Unit | Linkage |
|---|---|---|---|
| Polyethylene (PE) | \$C{2}H{4}\$ (Ethylene) | \$-CH{2}-CH{2}-\$ | C–C single bonds |
| Polystyrene (PS) | \$C{8}H{8}\$ (Styrene) | \$-CH{2}-CH(C{6}H_{5})-\$ | C–C single bonds |
| Polyvinyl chloride (PVC) | \$C{4}H{6}Cl_{2}\$ (Vinyl chloride) | \$-CH_{2}-CH(Cl)-\$ | C–C single bonds |
Condensation polymerisation involves the removal of a small molecule (usually water or methanol) each time two monomers join.
Imagine two Lego blocks snapping together and a tiny piece of plastic (the by‑product) falling off. 🧩
| Polymer | Monomers | Repeat Unit | Linkage |
|---|---|---|---|
| Nylon‑6,6 | Hexamethylenediamine + Adipic acid | \$-NH-(CH{2}){6}-NH-CO-(CH{2}){4}-CO-\$ | –NH–CO– linkages (amide bonds) |
| Polyester (PET) | Ethylene glycol + Terephthalic acid | \$-O-CH{2}-CH{2}-O-CO-(C{6}H{4})-CO-\$ | –O–CO– linkages (ester bonds) |
| Polyurethane | Polyol + Isocyanate | \$-O-CO-NH-CH{2}-CH{2}-O-\$ | –O–CO–NH– linkages (urethane bonds) |