A9.1 Addition and Condensation Polymers
Addition Polymerisation involves the joining together of many monomer molecules to produce one polymer chain and no other products. Addition polymers always have a continuous chain of carbon atoms.
Condensation Polymerisation involves joining together monomer molecules where there are two different functional groups which react together, join the monomer molecules and eject a small molecule in the process. This small molecule could be or .
The reactive functional groups are on opposite ends of the monomer molecules – so the two molecule chains are joined together leaving a tell-tale link which could be:
1. an ester link
An ester link – joining the two carbon chains R and R’ R and R’ could be the same or different chains
2.
An amide link
An amide link – joining the two carbon chains R and R
Polyesters : the two monomers need 1. an group and 2. a group.
Here we have a diol (ethan-1,2-diol) and benzene-1,2-dicarboxylic acid The molecule ejected during polymerisation is .
The OH group of the dicarboxylic acid could be replaced by a chlorine atom, in which case we would get the same polymer, but an molecule would be ejected.
Polyamides: the two monomers need 1. an group and 2. a group Here we have a dicarboxylic acid and a diamine. The molecule ejected dicarboxylic acid during the polymerisation is . Note the amide link.
The OH group of the dicarboxylic acid could be replaced by a chlorine atom, in which case we would get the same polymer, but an molecule would be ejected.
Carbohydrates and Proteins, often present in natural fibres, are examples of naturally occurring condensation polymers.
Nylon and Polyesters are examples of synthetic (man-made) polymers.
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