3.4.9 Polymers - Condensation polymers

Specification

Students should:
  • understand that condensation polymers may be formed by reactions between dicarboxylic acids and diols, between dicarboxylic acids and diamines and between amino acids
  • know the linkage of the repeating units of polyesters (e.g. Terylene) and polyamides (e.g. nylon 6,6 and Kevlar)

Condensation

This is otherwise known as addition - elimination, in other words a reaction that starts with addition of one molecule to another, followed by elimination of a small molecule, such as water, ammonia or a hydrogen halide.

Condensation reactions occur:

With amines

These all form amide (peptide) linkages between the two original molecular units

With alcohols

These all produce ester linkages between the original molecular units.

Condensation


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Condensation polymerisation

This can occur when each of the reacting molecules has two functional groups able to condense.

For example:

A diamine (A) and a dioyl chloride (B)

The molecules can then link together in a chain A-B-A-B-A-B- etc

Condensation polymerisation

Nylon 6,6


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