How is the elasticity of polymers explained chemically?

The elasticity of polymers is explained chemically through the movement and realignment of their long chain molecules.

Polymers are large molecules made up of repeating subunits called monomers. These monomers link together to form long chains, which can be flexible or rigid depending on the type of polymer. The elasticity of polymers is a result of the behaviour of these long chains when subjected to stress or strain.

When a polymer is at rest, its chains are tangled and disordered. However, when a force is applied, these chains can move and slide past each other, allowing the polymer to stretch or deform. This is similar to how a bundle of spaghetti behaves: when the bundle is at rest, the strands are tangled and disordered, but when you pull on the ends, the strands can slide past each other and the bundle becomes longer.

The ability of the chains to move and realign is dependent on the temperature and the type of bonds between the monomers. At low temperatures, the movement of the chains is restricted and the polymer behaves more like a solid, with a high degree of elasticity. At high temperatures, the chains can move more freely and the polymer behaves more like a liquid, with a lower degree of elasticity.

The type of bonds between the monomers also affects the elasticity. Polymers with strong covalent bonds between the monomers, such as plastics, have a high degree of elasticity because the chains can move and realign without breaking the bonds. Polymers with weaker bonds, such as rubber, have a lower degree of elasticity because the bonds can break when the chains move and realign.

In summary, the elasticity of polymers is explained chemically through the movement and realignment of their long chain molecules, which is influenced by the temperature and the type of bonds between the monomers.