polyesters and polyamides

• Types of polymerisation


  • Addition
  • Condensation
• Addition Polymerisation


  1. Unsaturated monomers react to form a polymer

  2. Monomers contain C=C bonds

  3. Chain forms when same basic unit is repeated over and over
• Poly(alkenes)


  • Chemically inert due to the strong C-C and C-H bonds and non-polar nature of the bonds and therefore are non-biodegradable
• You should be able to draw the polymer repeating unit for any alkene
• Condensation Polymerisation


  1. Two different monomers add together and a small molecule is usually given off as a side-product e.g. H2O or HCl

  2. The monomers usually have the same functional group on both ends of the molecule e.g. di-amine, di carboxylic acid, diol, diacyl chloride
• Polyesters


  Involve the formation of an ester linkage
• Polyamides


  Involve the formation of an amide linkage
• Forming polyesters and polyamides

  1. Carboxylic acid + alcohol -> ester + water

  2. Acyl chloride + alcohol -> ester + HCl

  3. Carboxylic acid + amine -> amide + water

  4. Acyl chloride + amine -> amide + HCl
• Polyesters


  • Terylene - used in clothing, tire cords
• Polyamides


  • Nylon 6,6
  • Kevlar
• It is also possible for polyamides and polyesters to form from one monomer, if that monomer contains both the functional groups needed to react
• Polyesters and polyamides can be broken down by hydrolysis and are, therefore, biodegradable
• Condensation polymers may be photodegradable as the C=O bond absorbs radiation
• Hydrolysis of polyesters and polyamides

  1. Can be hydrolysed by acid and alkali

  2. Results in the original monomers forming, with the carboxylic acid or amine group in salt form depending on whether the conditions are alkaline or acidic