Condensation polymerisation

What is condensation polymerisation?

A reaction where monomers with two different functional groups join together to form a polymer and a small molecule (often water) as a by-product.

How is condensation polymerisation different from addition polymerisation?

• Condensation: two types of functional groups, small molecule produced

• Addition: one monomer type (alkene), no small molecule produced

What small molecule is often produced in condensation polymerisation?

Water (H₂O).

What types of monomers are needed for condensation polymerisation?

Monomers with two functional groups, e.g., dicarboxylic acids and diols.

What is a polyester?

A polymer made by condensation polymerisation of a dicarboxylic acid and a diol (an alcohol with two –OH groups).

What is the functional group in polyesters?

–COO– (ester link).

What are the products of a polyester condensation reaction?

A polyester and water.

explain how a polyester is formed from condensation polymerisation and how to draw the repeat unit of the polymer

1. the OH from the COOH joins with the H from the diol OH to form water. This happens with each CCOH and OH group from the monomer. From what is left w can deduce the repeat unit of the polymer

2. start by rewriting what we have left over and straightening the double bonds

3. we then draw a bond between the carbon and oxygen atoms, and the ester linkage is the COO functional group within the repeating unit that forms an L shape

- there’ll be ester linkage formed from either end of this structure with another monomer

4. to draw the repeat unit add brakcets to the end with continuation bonds and add aqn ‘n’ to the outside of the brackets

for every ester link formed one molecule of ______ is released

water

why are polyesters biodegradable

- because other microorganisms can break down the ester linkage