Condensation Polymers (A2 Only)
Chemistry: AQA A Level, topic 6.6.1
Condensation Polymers
Condensation reactions can produce polymers if the reagent has two functional groups on either end of the molecule. It can form polyesters and polyamides.
Synthesis of polyesters
- Condensation reaction between diol and dicarboxylic acid monomers.
- Dicarboxylic acid derivatives can also be used, such as acid anhydrides and acyl chlorides.
- The mechanism is nucleophilic addition-elimination, shown above.
- The condensation reactions produce small molecules, alongside the polymer, such as H2 and HCl.
- Terylene is a polyester synthesised from ethane-1,2-diol and benzene-1,4-dicarboxylic acid.
Synthesis of polyamides
- Formed by the condensation reaction between diamine and dicarboxylic acid monomers.
- Again dicarboxylic derivatives can be used instead, such as acid anhydrides and acyl chlorides.
- Again, the mechanism is the same as for polyesters and a small molecule is also produced.
- Both fibres of Kevlar and Nylon-6,6 are polyamides.
Synthesis of polypeptides
- Proteins (polypeptides) are bipolymers formed from amide linkages. They are a specific type of polyamides.
- They are produced by condensation reactions between α-amino acids.
- α-Amino acids contain an amine and a carboxylic acid group at either end.
- These two groups can react to form the amide linkage.
Test yourself on Condensation Polymers (A2 Only)
Polyamide is formed from which of the following?