Polymer a large molecule of repeating units (monomer)

Identical monomershomopolymer

different monomerscopolymer

Polymers can be naturally occurring like silk or starch.

Polymers can be synthetically made like rubber, nylon or plastics.

Addition PolymersUnsaturated monomers (containing double bonds) are changed into single bonds as they join together in chains.

Other examples page 85

• Plastic is a polymer that can be shaped when exposed to heat or pressure, but is able to maintain its shape when cooled.

• Cross linking (the bonding of adjacent polymer chains through their functional groups) strengthens polymers so they are more rigid.

Eg. Adding of sulphur to rubber to make it more durable (called vulcanization).• Plasticizers can be added to add flexibility,

however they weaken the strength. They also increase reactivity causing adverse health effects on humans.

• Plastics are generally unreactive since they contain predominantly single bonded carbon.

All polymers are not plastic, but all plastics are polymers

Condensation Polymers

Addition of 2 reactive functional groups where a small molecule (like water) is eliminated.

Eg. An acid group reacts with an alcohol group polyester

Eg. An acid group reacts with an amine group polyamide

*these polymers can be made biodegradable by having bacteria break down the ester/amide links

Natural Polymers

• Carbohydrates (starch) is a polymer of a monosaccharide (a ketone or aldehyde with many OH side groups), like glucose.

• Amino acids contain a carboxylic acid and an amine. A protein polymer called a peptide is made up of 2 or more amino acids linked by a condensation reaction. Polypeptides lead to the formation of proteins.

• Nucleic acids are polymers made up of DNA/RNA that is responsible for protein synthesis