organosilicone

Organosilicone is a broad class of chemical compounds that contains silicon atoms bonded to carbon-containing groups and commonly features silicon–oxygen–silicon backbones. In practice, the term covers siloxanes and related polymers such as silicone oils, rubbers, resins, and gels, as well as small-molecule silanes. The defining feature is a silicon center bonded to organic substituents, with the Si–O–Si linkage prevailing in many polymers.

Structural types include silanes, where silicon is bonded to three substituents and halogen or hydroxy groups, and siloxanes, where silicon atoms are linked by Si–O–Si bridges with organic side groups (for example dimethylsiloxane units). Polysiloxanes, notably polydimethylsiloxane (PDMS), form the backbone of many commercial silicones. Related classes include cyclic siloxanes and silsesquioxanes, which can be used as monomers or fillers.

Properties common to organosilicones are thermal and chemical stability, low reactivity, and varying degrees of flexibility and viscoelasticity. PDMS, for instance, is optically clear, has a low glass transition, high gas permeability, and excellent weathering resistance, making it useful as a lubricant, sealant, or silicone elastomer. Other forms include silicone oils, gels, and resins with tailored hardness and cure chemistries.

Synthesis typically proceeds by hydrolysis and condensation of chlorosilanes or through hydrosilylation to attach functional groups; polymerization of cyclic siloxanes yields high-molecular-weight silicone polymers. Applications span consumer products, medical devices, electronics, construction, and cosmetics, reflecting the combination of stability, biocompatibility, and insulating properties.

Safety and environmental notes: most organosilicones exhibit low acute toxicity, but environmental persistence and regulatory scrutiny exist for certain cyclic siloxanes and related species.