Condensation polymerisation

The formation of two or more (usually different) monomers in a condensation reaction where a small molecule (usually water) is eliminated and a polymer is formed.

Polyesters, polyamides and polypeptides

• Polyesters are formed from diols and docarboxylic acids • The hydroxyl group and carboxyl group form an ester linkage and a molecule of water is eliminated per water bond formed. • The -OH from the hydroxyl group and the hydrogen from the -OH of the carboxyl group form the molecule of water.

A polyester made from benzene-1,4- dicarboxylic acid and ethane-1,2-diol.

• Polyamides are formed from diaminoalkanes/diamines and dicarboxylic acids • One of the hydrogens from the amine (-NH2) group reacts with the -OH from the carboxyl group to eliminate a molecule of water. • The amide linkage is formed

• A polyamide • Industrially it is formed from 1,6-diaminohexane and hexane-1,6-dicarboxylic acid. • In the lab it the reaction goes faster if a diacid chloride is used rather than the dicarboxylic acid: in this case, chlorine is eliminated.

• A polyamide • Kevlar is made from benzene-1,4-diamine and benzene-1,4-dicarboxylic acid. • Kevlar’s strength is due to the rigid chains and the ability of the flat aromatic rings to pack together held by strong intermolecular forces.

• Polypetides are a type of polyamide. • In a polypeptide each amino acid has both an amine group and a carboxyl group. • The amine group of one amino acid reacts with the carboxyl group of another. • A molecule of water is formed per each bond formed.

Addition polymers are basically long chain alkanes which are polar and unreactive.

• They are usually disposed of in landfill sites or by incineration. • Some addition polymers can be melted and remoulded. • Poly(alkenes) can be burnt to carbon dioxide and water to produce energy, although poisonous carbon monoxide may be produced as a result of incomplete combustion. • Burning poly(alkenes) also adds to the problem of increasing the carbon dioxide level in the atmosphere. • Other addition polymers can release toxic products upon burning such as toxic styrene gas.

• Condensation polymers can be broken down by hydrolysis. • This makes them biodegradable.

In the presence of a strong acid or specific enzyme

Heat in 6-molar concentrated HCl. This process takes roughly 24 hours.

Hot, aqueous alkalis such as sodium hydroxide.