Silicones are a family of specialty, high-performance polymers that can be manufactured in more than 2,000 forms, from liquids to pastes to rubber. Silicones usually are produced in a multi-step-process starting from silica.
The first step in making silicones is the retrieval of the element silicon (Si) from silica (generally known as sand). Silicon is the second most abundant element found in the earth’s crust. The silicon then is transformed into silanes; molecules where the silicon atom is attached to carbon-based chemical groups and to other more reactive chemical groups. Within a complicated sequence of chemical reactions, involving mainly the other reactive chemical groups in the silanes – which are effectively removed during the process – chains, cycles and crosslinked structures are formed. They generally are built around a backbone of silicon and oxygen (Si-O-Si-O)-repeating units with the carbon-based chemical groups still being attached to the silicon atoms.
Shorter chains or cycles of these products are called siloxanes, while longer chains and crosslinked structures are named as silicones. Siloxanes sometimes are isolated and stored to be used later to generate specific siloxanes or silicones or in some smaller quantities to be used directly (e.g. as a solvent). Modifying the silicon-oxygen backbone by the addition of carbon-based chemical groups produces polymers that in essence combine the physical qualities of a metal (Si) with the diversity of plastics (carbon chemistry). The result is a family of extremely durable, versatile materials with a wide range of high-performance properties.
For an interactive look at silicones chemistry, please visit: siliconesinfo.com/about-silicones/silicones-chemistry