Polymers

• Addition polymerisation


  An addition polymer forms when unsaturated monomers react to form a polymer
• Addition polymers


  • Monomers contain C=C bonds
  • 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
• Drawing the polymer repeating unit for any alkene


  1. First draw out the monomer with groups of atoms arranged around the double bond

  2. e.g. For but-2-ene
• Condensation polymerisation


  Two different monomers add together and a small molecule is usually given off as a side-product (e.g. H2O or HCl)
• Common types of condensation polymers

  • Polyesters
  • Polyamides
• Monomers for condensation polymers

  Usually have the same functional group on both ends of the molecule (e.g. di-amine, di carboxylic acid, diol, diacyl chloride)
• 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
• Terylene - a common polyester


  • Ethane-1,2-diol
  • Benzene-1,4-dicarboxylic acid
• Forming polyesters and polyamides from diacyl dichlorides and diols/diamines

  1. diacyl dichloride + diol → poly(ester) + HCl

  2. diacyl dichloride + diamine → poly(amide) + HCl
• Nylon 6,6 - a common polyamide

  • Hexanedioic acid
  • Hexane-1,6-diamine
• Kevlar - a common polyamide

  Formed from 4-hydroxypentanoic acid and 4-hydroxybutanoyl chloride
• Poly(lactic acid)


  Formed from 2-hydroxypropanoic acid (lactic acid)
• Landfill is the most common method of disposal of waste in the UK
• Many landfills are now reaching capacity
• Most polymers (polyalkenes) are non-biodegradable and take many years to break down
• Incineration can release toxins but modern incinerators can burn more efficiently and remove most toxins and pollutants
• Recycling


  • Saves raw materials
  • Polymers need collecting/sorting - expensive process in terms of energy and manpower
  • Polymers can only be recycled into the same type – so careful separation needs to be done
  • Thermoplastic polymers can be melted down and reshaped
• Hydrolysis


  Polyesters and polyamides can be hydrolysed by acid and alkali, resulting in the original monomers forming
• Intermolecular bonding in condensation polymers

  • Polyesters have permanent dipole forces between the Cδ+=Oδ- groups
  • Polyamides have hydrogen bonding between the oxygen in Cδ+=Oδ- groups and the H in the Nδ- —Hδ+ groups
• Polyamides will have higher melting points than polyesters due to the stronger hydrogen bonding
• Polar bonds in condensation polymers

  Can attract attacking species such as nucleophiles and acids