Polydimethylsiloxane is the basic and most commonly available silicone.

By adjusting -Si-O- chain lengths, the functionality of the side groups and the crosslinking between molecular chains, silicones can be synthesized into an almost infinite variety of materials.

Polydimethylsiloxanes are obtained by the hydrolysis of the dimethyldichlorosilane in the presence of an excess of water according to:

» Condensation and Polymerisation

However, the linear and cyclic oligomers obtained by hydrolysis of the dimethyldichlorosilane have too short a chain for most applications. They need to be condensed (linears) or polymerised (cyclics) to give macromolecules of sufficient length.