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
• You should be able to draw the polymer repeating unit for any alkene
• It is best to first draw out the monomer with groups of atoms arranged around the double bond
• Condensation polymerisation

  Two different monomers add together and a small molecule is usually given off as a side-product
• 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
• Polyesters


  • Terylene
• Polyamides


  • Nylon 6,6
• Acyl chloride goes to completion and does not need a catalyst but does produce hazardous HCl fumes
• It is also possible for polyamides and polyesters to form from one monomer, if that monomer contains both the functional groups needed to react
• Polymers formed from one monomer

  • Kevlar
• Some compounds can form various cyclic esters under different conditions from forming the polymer
• Polymers formed from one monomer

  • Poly(lactic acid)
• Landfill

  • The most common method of disposal of waste in UK
  • Many are now reaching capacity
  • European regulations will mean councils are charged much more for using landfill
  • Most polymers (polyalkenes) are non-biodegradable and take many years to break down
• Incineration

  • Rubbish is burnt and energy produced is used to generate electricity
  • Some toxins can be released on incineration
  • Modern incinerators can burn more efficiently and most toxins and pollutants can be removed
  • Greenhouse gases will still be emitted though
  • Volume of rubbish is greatly reduced
• Recycling

  • Saves raw materials- nearly all polymers are formed from compounds sourced/produced from crude oil
  • 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
  • The hydrolysis will result in the original monomers forming- although the carboxylic acid or amine group will be in salt form depending on whether the conditions are alkaline or acidic
• Intermolecular bonding in condensation polymers

  • Polyesters have permanent dipole forces between the Cδ+=Oδ- groups in the different chains in addition to the van der waals forces between the chains
  • Polyamides (and proteins) have hydrogen bonding between the oxygen in Cδ+=Oδ- groups and the H in the Nδ- —Hδ+ groups in the different chains in addition to the van der waals forces
  • Polyamides will therefore have higher melting points than polyesters
• The reactivity of condensation polymers can be explained by the presence of polar bonds which can attract attacking species such as nucleophiles and acids