Synthetic and naturally occurring polymers

• Alkenes can be used to make polymers such as poly(ethene) and poly(propene) by addition polymerisation.
• In addition polymerisation, many small molecules (monomers) join together to create very large molecules (polymers).
• The repeat unit in addition polymerisation has the same atoms as the monomer because no other molecule is formed in the reaction.
• When drawing out a polymer, make sure to draw the bonds coming off the C’s out of the brackets and the little ‘n’ (means there are large numbers of these molecules joined together).
• Condensation polymerisation involves monomers with two functional groups, and when they react, they join together, usually losing small molecules such as water, and so the reactions are called condensation reactions.
• The simplest polymers are produced from two different monomers with two of the same functional groups on each monomer.
• Amino acids have two different functional groups in a molecule (an amine group and a carboxylic acid group), and they react by condensation polymerisation to produce polypeptides.
• Different amino acids can be combined in the same chain to produce proteins.
• DNA (deoxyribonucleic acid) is a large molecule essential for life, it encodes genetic instructions for the development and functioning of living organisms and viruses.
• Most molecules of DNA are two polymer chains, made from four different monomers called nucleotides, in the form of a double helix.
• Other naturally occurring polymers important for life include proteins (monomer= amino acid), starch (monomer= glucose) and cellulose (monomer= glucose).