Production of a large molecule from reactions of monomers in which a small molecule,
such as water, is eliminated. Condensation polymers involve two functional groups.
Polyamide A polymer made by the linkage of an amino group and a carboxylic acid group (CONH)
Polyesters contain the linkage -COO- and are made from diols and dicarboxylic acids. When polyesters
are made, water is eliminated. Terylene is a polyester used in plastic bottles, made from benzene-1,4-
dicarboxylic acid and ethane-1,2-diol.
Polyamides are formed when dicarboxylic acids and diaminoalkanes react, forming -CONH- linkages and
eliminating water. Nylon-6,6 is made from 1,6-diaminohexane and hexane-1,6-dicarboxylic acid, and is
used, and is used in thread and raincoats. Kevlar is made from benzene-1,4-diamine and benzene-1,4-
dicarboxylic acid. Since the flat aromatic rings allow tight packing, it has very high strength and is
therefore used in bullet-proof vests and anti-stab clothing.
Polypeptides are also polyamides, but instead are made from amino acids, each of which have an amine
group and a carboxylic acid group.
When drawing repeated units, start at a point in the polymer and stop when the same pattern
reappears. To identify the monomers, break the linkage in the repeat unit and add the components of
water to the link.
Polyalkenes are inert and not biodegradable as they have only strong, non-polar C-H and C-C bonds.
Some may be left on landfill sites, some are burnt and some are recycled.
Condensation polymers can be broken down by hydrolysis and are therefore potentially biodegradable
as they possess a polar C=O bond, allowing attack by water.
Landfill Burning Recycling
Pros • Cheap • No space taken
• Less space wasted
• Reduced emissions
• Less crude oil used – preserves supply
• Saves money
Cons • Land is used
• Plastics not
• Toxic gases
• Harmful to
• Global Warming
• Separation can be difficult and expensive
• Quality of recycled polymer reduced due to
• Strength decreases with each recycle
• Melting plastics emits harmful gases