Module 6.2.3- Polyesters and polyamides

• Condensation polymerisation


  a reaction in which monomers are linked together into a polymer with the release of a small molecule, such as water, as a by-product
• Polyester

  monomers are joined together by ester linkages in a long chain to form the polymer
• How are polyesters made

  made from a monomer containing a carboxylic acid group and an alcohol group
• Repeat unit (revision)


  A specific arrangement of atoms that occurs in the structure over and over again. Repeat units are included in brackets, outside of which is the symbol n.

  
• Polyesters made from two monomers each containing two functional groups


  One monomer is a diol

  One monomer is a dicarboxylic acid

  
• Polyamides


  condensation polymers that contain the amide functional group
• Polyamides from one monomer with two functional groups

  Amide bond is formed and water is lost

  
• Polyamides from two monomers each with two functional groups

  can be made with a diamine and a dicarboxylic acid (or acyl chloride)

  
• What are the two reagents you can use to hydrolyse condensation polymers?


  Hot aqueous alkali

  Hot aqueous acid
• Hydrolysing polyesters

  alkali hydrolysis forms a carboxylate ion salt

  
• Hydrolysing polyamides

  the H+ in acid hydrolysis can protonate COO- to COOH and NH₂ to NH₃+ in the monomers produced. there isn't a proton in base hydrolysis so this doesn't happen.

  
• Summary of acid and alkali hydrolysis on condensation polymers (regarding NH2 and COOH)

  Hot aqueous acid = NH3+ and COOH

  Hot aqueous alkali= NH2 and COO-