7.3.2 Condensation Polymerisation (HT only)

In condensation polymerisation, two monomers with two functional groupsAny group of atoms in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest of the molecule's composition. each react to form a polymer while releasing a small molecule such as water. This process is called a condensation reaction because of the elimination of the small molecule during polymer formation.

The simplest form of condensation polymerisation involves two different monomers, each with two identical functional groups. When these monomers react, they join together through the functional groups, resulting in the formation of a polymer.

For example, the monomers ethanediol (a diol with two hydroxyl functional groups) and hexanedioic acid (a dicarboxylic acid with two carboxyl functional groups) can undergo condensation polymerisation to form a polyester. During the polymerisation process, the hydroxyl group of ethanediol reacts with the carboxyl group of hexanedioic acid, releasing a molecule of water. The repeating unit of the resulting polyester will contain the functional groups of both monomers.