Synthetic Polymers

• Polymers are large molecules of high molecular mass • Addition polymers are made of a large number of smaller molcules known as monomers which are joined together by covalent bonds • These monomers must contain a C=C bond before polymerisation occurs, which is why the monomers of most addition polymers are alkenes (though some have a group containing other atoms attached to them such as a chlorine of hydroxl group) • Examples of polymers include plastics, polysyrenes and nylon • Some are manufactured which are known as synthetic polymers while others are found in nature which are known as biological polymers

• Monomers will join together in a process known as addition polymerisation • Addition polymers only form with monomers that contain a C=C bond • When an addition polymer is formed, one of the bonds in the C=C bond of each monomer will break and a bond will be formed with the adjacent monomer • The process of addition polymerisation usually occurs under high pressures and with catalysts • You name addition polymers by adding ‘poly’ to the name of the monomers - if propene was used as the monomer the addition polymer would be called polypropene

• Draw the monomer without the double covalent bond (some groups of the monomer are drawn in slightly differently) • Place brackets around it but extend the bonds out past the brackets • Place an ‘n’ next it on the bottom right

• Identify the repeating unit • Change the single carbon bond to a double bond • Remove the extension bonds from each end and move the ‘n’ to the left of the monomer

• The strong single carbon bonds makes polymers very unreactive and chemically inert • This means that they are not able to biodegrade, so will fill up landfills quickly and can be consumed by animals

• They release alot of heat energy as well as carbon dioxide which contributes to climate change when burnt • Addition polymers such as polychloroethene will release hydrogen chloride when burnt which is toxic • If incinerated via incomplete combustion, carbon monoxide will be produced which is also toxic Addition polymers can be recyled but the process is very expensive as the polymers must be seperated

• High melting and boiling point • Large molecules with a high mass • Flexible, ductile and malleable

• A diol is an alcohol with two functional groups, one on each end • A dicarboxylic acid is a carboxylic acid with two functional groups, one on each end The displayed formula of ethanedioic acid (oxalic acid) is shown as an example

• Condensation polymerisation has the monomers of a diol and a dicarboxylic acid • In each linkage between the two, the polymer and a molecule of water will be produced • When linking, the functional groups at the end of one monomer link with the functional group at the end of the other monomer (in a similar way to an esterification reaction) • This creates long chains of alternating, bonded monomers, forming the condensation polymer • The polymers formed from these reactions are called polyesters

• Draw the ester that would be formed but with functional groups on either end • Exclude the O-H on the end of the dicarboxylic functional groups and the H on the end of the dialcohol functional groups which are lost in the linkage • Add brackets, the extension bonds and the ‘n’

Often the non-functional group parts will be represented by a box or as structural formula (e.g. CH₂) as they are unimportant

• They are specific types of polyesters synthesised from organic material such as plant oils • They are, of course, types of condensation polymers • They are able to biodegrade naturally in the environment after their intended purpose