23. Macromolecules
Macromolecules
Addition Polymerisation
Condensation Polymerisation
Nylon - a Polyamide
Pollution Problem caused by Plastics
- Macromolecules are very large molecules made by joining thousands of identical small molecules called monomers.
- The process of chemically joining up the monomers is called polymerization.
- The very large molecule formed is called the polymer.
Addition Polymerisation
- An addition polymer is formed when unsaturated monomers, containing C=C bonds, joined up to form a polymer without any loss of atoms.
- The C=C bonds become C-C single bonds in the process.
Condensation Polymerisation
- Condensation polymers are made from monomers containing alcohol, acid or amino (-NH2) functional groups.
- At least 2 types of monomers are alternately chemically joined together, in a condensation reaction, to form a large molecule.
- In the condensation reaction, for every linkage formed, a small molecule, such as water, is removed.
Nylon - a Polyamide
- Nylon is made from condensation polymerisation.
- Diamine molecules and dicarboxylic acid molecules react together.
- Water molecules are removed in the process.
- An amide linkage is formed. -CONH-
- Nylon is used to make ropes, fishing lines, clothes, tents and parachutes.
- Terylene is made from condensation polymerisation.
- Diol molecules and dicarboxylic acid molecules react together.
- Water molecules are removed in the process.
- An ester linkage is formed. -COO-
- Terylene is made into fibres which are woven into cloth which do not wrinkle easily.
Pollution Problem caused by Plastics
- Plastics are non-biodegradable, which means that they are not broken down easily into simpler substances by microorganisms like bacteria and fungi in soil.
- When burnt, they produce toxic gases like CO and HCl which pollute the air.
- When discarded, plastics do not decompose and take up landfill space.