Ch 15Polymers — Class 12 Chemistry, concept-first.

Imagine life without plastic buckets, synthetic clothes, tyres, toys, and electrical insulation — this whole family of materials exists because of polymers, and they form the backbone of four major in…

Every polymer is built by one of two broad mechanisms:

The most widely used route to addition polymers is the free-radical mechanism. Alkenes, dienes, and their derivatives are polymerised in the presence of a free-radical-generating initiator (sometimes…

1. Chain initiation

Polythenes are long, linear or slightly branched chains built from ethene. Because they soften on heating and re-harden on cooling, they are thermoplastics.

The second big family is condensation (step growth) polymerisation. Instead of monomers simply adding on to a growing radical chain, here the polymer is built by a repeated condensation reaction betwe…

Polymers built with amide linkages are the synthetic fibres we call nylons. They are generally made either by condensing a diamine with a dicarboxylic acid, or by condensing an amino acid (or its cycl…

Copolymerisation is polymerisation carried out with a mixture of more than one kind of monomer, so that the resulting chain — the copolymer — contains multiple units of each monomer used.

Rubber is a natural, elastic polymer — an elastomer. In elastomers, the individual polymer chains are held together only by weak intermolecular forces, which is exactly what lets the material be stret…

A polymer's physical properties — its strength, flexibility, melting behaviour, and more — are tied closely to its molecular mass, size, and structure.

Most everyday polymers are deliberately built to be tough and resist breaking down — which is great for durability, but means they persist as solid waste in the environment for a very long time, causi…

Beyond the polymers already covered chapter by chapter, several other polymers are important enough commercially that it's worth knowing their monomer, repeating structure, and typical uses side by si…