In this video you will learn how
condensation polymers form, some examples
of condensation polymers and the uses of these polymers. Unlike addition polymers
where monomers react to form a single
product, in a condensation polymerization
reaction
not only is the polymer formed but also
a small molecule is eliminated or lost,
normally water. Polyesters and polyamides are the two types of condensation
polymer we will look at. We will first look
at polyamides. This is known as the amide link.
It is formed when a carboxylic acid
reacts with an amine. In the formation of
nylon 6,6 we react a molecule with an amine group on each side known as
hexane-1, 6-diamine and a molecule with a carboxylic acid at each end, hexanedioic acid.
Since both these molecules have long chain carbons, they are only complicated the
visual structure. Let us remove these and
replace them with rectangular blocks. You
can now see the functional groups at the
ends of each molecules. A carboxylic acid
and amine group positioned next to each other. These groups reacts to form water,
which is eliminated. And a large polymer
molecule is formed, held together by amide
links. Hence the name Polyamide. Nylon has many uses in the textile industry but
this is also structurally sound material
used in engineering. Especially where low
friction is required, such as in bearings
or bushes.
We can now look at polyesters in a
similar way. An ester is formed in the
reaction of an alcohol with a carboxylic
acid.
In this example we will show the
formation of polyethylene terephthalate,
more commonly known as PET. Using the
carboxylic acid Benzene-1, 4-dicarboxylic
acid and the alcohol ethane-1, 2-diol.
Once again since those these molecules
have a long carbon chain that may
confuse the overall structure we will
replace them with rectangular blocks. As
you can see when we align the two
molecules, a carboxylic acid and alcohol
group can react between the molecules
causing Ester links to hold the large
polymer molecule together. And once again
water is released.
PET is commonly used as a plastic for
drinks bottles and polyester is used to
produce fabric for clothing. Now at the
end of this tutorial you should
understand what condensation polymers
are and be able to give examples of
polyesters and polyamides along with
their uses.
