Nylon was first introduced around 1939 and was in high demand to make stockings. However, as World War 2 progressed, nylon was used more and more to make parachutes, and so stockings became more difficult to buy. After the war, when manufacturers were able to shift their focus from parachutes back to stockings, a number of riots took place as women queued to get stockings. In one of the worst disturbances, 40 000 women queued up for 13 000 pairs of stockings, which led to fights breaking out!
Polymers
The following monomer is a reactant in a polymerisation reaction:
What is the IUPAC name of this monomer?
Give the structural formula of the polymer that is formed in this polymerisation reaction.
Is the reaction an addition or condensation reaction?
The polymer below is the product of a polymerisation reaction.
Give the structural formula of the monomer in this polymer.
What is the name of the monomer?
Draw the abbreviated structural formula for the polymer.
Has this polymer been formed through an addition or condensation polymerisation reaction?
A condensation reaction takes place between methanol and methanoic acid.
Give the structural formula for...
methanol
methanoic acid
the product of the reaction
What is the name of the product? (Hint: The product is an ester)
The chemical properties of polymers
The attractive forces between polymer chains play a large part in determining a polymer's properties. Because polymer chains are so long, these interchain forces are very important. It is usually the side groups on the polymer that determine what types of intermolecular forces will exist. The greater the strength of the intermolecular forces, the greater will be the tensile strength and melting point of the polymer. Below are some examples:
Hydrogen bonds between adjacent chains Polymers that contain amide or carbonyl groups can form
hydrogen bonds between adjacent chains. The positive hydrogen atoms in the N-H groups of one chain are strongly attracted to the oxygen atoms (more precisely, the lone-pairs on the oxygen) in the C=O groups on another. Polymers that contain
urea linkages would fall into this category. The structural formula for urea is shown in
[link] . Polymers that contain urea linkages have high tensile strength and a high melting point.
The structural formula for urea
Dipole-dipole bonds between adjacent chains Polyesters have
dipole-dipole bonding between their polymer chains. Dipole bonding is not as strong as hydrogen bonding, so a polyester's melting point and strength are lower than those of the polymers where there are hydrogen bonds between the chains. However, the weaker bonds between the chains means that polyesters have greater flexibility. The greater the flexibility of a polymer, the more likely it is to be moulded or stretched into fibres.
Weak van der Waal's forces Other molecules such as ethene do not have a permanent dipole and so the attractive forces between polyethene chains arise from weak
van der Waals forces. Polyethene therefore has a lower melting point than many other polymers.
