Polymerisation Types and Properties: Polymers, Monomers, and Applications

Polymerisation

A chemical reaction where many small monomers join together to form a large polymer.

Monomer

A small molecule that can join repeatedly with other monomers to form a polymer.

Polymer

A large molecule made from many repeating monomer units joined together.

Addition polymerisation

Unsaturated monomers containing C=C bonds join when the double bonds open. Only the polymer is produced.

Condensation polymerisation

Monomers with two functional groups join together, forming the polymer and releasing a small molecule, usually water.

Addition polymers

Polyethylene, PVC, polystyrene and PTFE.

Condensation polymers

Nylon and polyesters.

Thermoplastic

A polymer with separate chains held together by intermolecular forces. It softens when heated and can be remoulded.

Thermosetting polymer

A polymer with many covalent cross-links between chains. It is rigid and does not melt when heated.

Elastomer

A polymer with a small number of cross-links, allowing it to stretch and return to its original shape.

Polyethylene (PE)

An addition polymer made from ethene. Its chains are non-polar and experience dispersion forces.

LDPE structure

Polyethylene with lots of branching, preventing the chains from packing closely together.

LDPE properties

Weaker, softer, more flexible and lower density because its branched chains have weaker dispersion forces.

LDPE uses

Plastic bags and flexible plastic film.

HDPE structure

Polyethylene with little branching, allowing the chains to pack closely together.

HDPE properties

Stronger, stiffer and higher density because close packing produces stronger dispersion forces.

HDPE uses

Buckets, bins, bottles and cutting boards.

PVC

An addition polymer made from chloroethene. It contains polar C-Cl bonds and bulky chlorine side groups.

PVC properties

Strong and rigid because C-Cl bonds create dipole-dipole attractions and the bulky chlorine groups restrict chain movement.

PVC uses

Pipes and gutters. Plasticisers can be added to make PVC flexible for hoses and cables.

Polystyrene

An addition polymer made from styrene. It contains bulky benzene rings attached as side groups.

Polystyrene properties

Hard, rigid and brittle because its bulky benzene side groups restrict movement of the polymer chains.

Polystyrene uses

Rigid containers and packaging. Expanded polystyrene is lightweight and insulating.

PTFE

An addition polymer made from tetrafluoroethene, with repeating -CF2-CF2- units.

PTFE properties

Chemically unreactive, heat resistant, hydrophobic and low-friction because of its very strong C-F bonds.

PTFE uses

Non-stick cookware coatings, electrical insulation and chemical-resistant materials.

Nylon

A condensation polymer called a polyamide because its polymer chains contain repeating amide links.

Nylon formation

A diamine reacts with a dicarboxylic acid, forming amide links and releasing water.

Nylon intermolecular forces

Amide groups form hydrogen bonds between neighbouring polymer chains.

Nylon properties

Strong, tough and abrasion resistant with high tensile strength because of hydrogen bonding between chains.

Nylon uses

Rope, stockings, carpets, airbags and parachutes.

Polyester

A condensation polymer containing repeating ester links.

Polyester formation

A diol reacts with a dicarboxylic acid, forming ester links and releasing water.

Polyester intermolecular forces

Polar ester groups create dipole-dipole attractions between polymer chains.

Polyester properties

Strong, durable and resistant to stretching and abrasion.

Polyester uses

Textiles, carpets and PET plastic bottles.

Nylon vs polyester

Nylon contains amide links and can form hydrogen bonds between chains, while polyester contains ester links and mainly has dipole-dipole attractions.