We saw earlier in discussions about functional groups that chemists can subtly change the properties of molecules by unscrewing a functional group here and replacing another one there. Altering the structure and hence the properties of a an important evolutionary molecule such as adrenaline can lead to drugs like amphetamine, methamphetamine and MDMA. (Can you spot the error in the video?)
Chemists involved in developing new polymers take a similar approach. Ethene under the influence of pressure and catalyst can polymerise to form polythene. Polythene has many desirable properties but also one major drawback, it can’t be manufactured with colour.
If one of the hydrogen atoms in ethene is replaced with a chlorine atom the molecule chlorethene results. (vinyl chloride). When this molecule undergoes addition polymerisation the plastic polyvinyl chloride or PVC is produced. The addition of chlorine atoms into the long polymer chain results in a substance that can be manufactured in a variety of bright colours.
Poly vinyl chloride was dicovered twice in the nineteenth century. It was in the 60’s however that PVC became popular as a material that could be used to make fashionable clothes. After the austere years following the second world war the public demanded bright fashions and new music to go with them. The Austin Powers movies are a clever parody of the sixties and catch the colour of the times well.
How many pieces of shiny bright coloured clothing can you find in the clip from the Austin Powers movie?
Alkenes and addition polymerisation, writing equations
NCEA questions often ask you to show what the polymer chain would look like if three monomer units are combined. You can also be asked to draw the structural formula of the monomer that produced a polymer