Condensation Polymerization Overview

Study Notes

Condensation polymers are formed when a water molecule is removed during the reaction.
There are three main types of condensation polymers: polyamides, polyesters, and polypeptides.

Polyamides are formed by reacting a dicarboxylic acid with a diamine.
A water molecule is removed, creating an amide linkage (-CONH-)
Examples of polyamides include nylon-6,6, made from hexamethylenediamine and hexanedioic acid, and Kevlar, made from 1,4-benzenedicarboxylic acid and 1,4-benzenediamine.
Long chain molecules provide polyamides with strength.

Polyesters are produced by reacting dicarboxylic acids with a diol.
The reaction forms an ester linkage (-COO-).
A common example is Terylene (PET), made from ethanediol and 1,4-benzenedicarboxylic acid.

Polypeptides are formed from multiple amino acids.
A single monomer can produce a polymer due to the presence of both a -NH and -OH group.
The linkage in polypeptides is a peptide linkage (-CONH-).

Condensation polymers can be broken down into their constituent molecules by adding water (hydrolysis).
This occurs because water is attracted to the polar regions of the polymer, breaking the links.

Condensation polymers contain polar bonds like those in ester and amide linkages.
Hydrogen bonding and dipoles can form between separate polymer chains, leading to strong structures.
This makes them suitable for applications like bulletproof vests and heat-protective materials.

Polyalkenes (addition polymers) are very inert and have non-polar bonds, making them non-biodegradable.
They are often broken down by burning, which produces harmful products like SO2 and CO, contributing to acid rain.
Polyesters and polyamides are biodegradable due to the polarity within their molecules, allowing them to be broken down by water or moisture.
They can be disposed of in landfills, where they will gradually decompose.
Some plastics can be recycled, reducing waste and conserving resources, but this process is difficult and time-consuming, requiring sorting and washing.