3.3.12.1. condensation polymers

• when do condensation polymers form?

  when a water molecule is removed from the species of a reaction
• polyamides

  • formed in a reaction between dicarboxylic acid and a diamine
  • a water molecule is removed, leaving an amide linkage

  
• polyamide example


  nylon-6,6 made from hexamethylenediamine and hexanedioic acid

  
• common polyamide - kevlar

  made from 1,4-benzenedicarboxylic acid and 1,4-benzenediamine

  
• what are polyamides commonly formed from?

  long chain molecules - provides them with strength
• polyesters


  formed from dicarboxylic acids and a diol - ester linkage (-COO)

  
• common polyester - Terylene (PET)


  formed from ethanediol and 1,4-benzenedicarboxylic acid

  
• polypeptides

  • formed from multiple amino acids
  • single monomer can produce a polymer due to the presence of both a -NH and -OH group
  • -CONH- is the peptide linkage

  
• hydrolysis 


  condensation polymers can be broken down back not the constituent molecules by the addition of water
• hydrolysis - use of water


  water is attracted to the polar regions of the polymer so the links can be broken down
• hydrolysis mechanism

  
• uses of condensation polymers

  • condensation polymers contain polar bonds e.g. those in the ester and amide links
  • H-bonding and dipoles can form between separate polymer chains, holding them together in a strong structure
  • this makes the polymers very useful for things e.g. bulletproof vests and heat protective materials