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:
Figure 9.1 An ester link
An ester link – joining the two carbon chains R and R’
R and R’ could be the same or different chains
Figure 9.2 An amide link
An amide link – joining the two carbon chains R and R
- Polyesters : the two monomers need 1. angroup and 2. agroup.
Figure 9.3 Polyester
- 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 anmolecule would be ejected.
- Polyamides: the two monomers need 1. angroup and 2. agroup 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 anmolecule would be ejected.
Figure 9.4 Polyamide
- 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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