polymers

• The small units that react together to make the polymer are called monomers
• What happens in addition polymerisation?


  • The pi bond of the C=C bond is broken and the monomers become linked together
• Condensation polymerisation can be split into two steps: addition and then, elimination of water or HCL
• What are formed from condensation polymerisation?


  Polyesters and Polyamides
• Proteins are an example of a polymer made from a long chan of amino acids
• polyesters are formed when carboxylic acids react with alcohols in the presence of acid catalyst
• carboxylic acid + alcohol ——> ester + water (this reaction is reversible
• a polyester has the ester linkage -COO-
• To make a polyester dicarboxylic acid and diols react together
• when you react acyl chloride + alcohol it forms an polyester + HCL
• What intermolecular forces are present in polylactic acid?


  • weak van der waals
  • dipole-dipole
• When are amides formed?


  When carboxylic acids react with amines in the presence of a catalyst
• carboxylic acid + amine —-> amide + water ( this is a reversible reaction
• what linkage does polyamides have?


  • amide linkage -CONH-
• Why are Nylons widely used in making clothes and climbing robes?


  • because it has low density
  • many strength
  • high elasticity
• How can Nylon be formed?


  hexanedioyl dichloride
• what is nylon 


  a polyamide
• What are the positives and negatives for using nylons 


  • more reactive therefore quicker
  • but more expensive than hexanedioic acid
• Kevlar is an example of polyamide made by reacting dicarboxylix acid and diamine. It is strong, resistant to fire and flexible. Its strength is due to the rigid chains and the ability of the the flat aromatic rings to pack together held by strong intermolecular forces. It is used in bullet-proof vests and anti-stab vests, in addition to being used for heat protection in oven gloves
• What intermolecular forces are present in the polymer kevlar 


  • hydrogen bonding
  • van der waals
  • dipole- dipole