Addition Polymerisation

• Polymers are large molecules built up from small molecules called monomers
• Polymerisation is where several short chained monomers break their double bonds to form one long chain saturated molecule

  
  

  e.g 1

  Poly(ethene) which is used to make plastic bags

  
• e.g2

  Poly(Propene) which is used to make plastic bowls and ropes

  N.b Lines must cross to outside of brackets

  
• E.g 3

  
  

  Poly(Styrene) Conditions are Heated in presence of benzoyl peroxide

  Has many insulating properties

  N.b Bonds must cross outside brackets

  
• The main chain of polymers are normally non-polar, meaning they are very unreactive : C-H, C-C
• The properties of polymers are effected by the intermolecular forces;

  Longer chains with fewer branches have stronger van der Waals forces because the polymer chains can pack closer together meaning they are more rigid(less flexible) and have higher melting points e.g poly(ethene)

  Large chains with branches, find it difficult to pack closely therefore have weaker van der Waals forces but are more flexible e.g Poly(styrene)
• Some Addition Polymers are Polar, this meaning that there are Stronger Permeant dipole-dipole forces of attraction between the Polymer chains which makes the polymers Hard but Brittle e.g PolyChloroethene (PVC)