Silicones

Silicones are a family of polymeric and oligomeric compounds based on a siloxane backbone of alternating silicon and oxygen atoms, with organic groups attached to silicon. The most common repeating unit leads to polymers such as poly(dimethylsiloxane) (PDMS). Silicones include fluids, elastomers, resins, and gels, as well as cyclic siloxanes used as intermediates and solvents.

These materials are typically synthesized by hydrolysis and condensation of silanes or chlorosilanes, or by equilibration of cyclic siloxanes to form high-molecular-weight networks. They exhibit properties such as high thermal stability, chemical inertness, wide temperature tolerance, high dielectric strength, low surface energy, and tunable viscosity and elasticity, allowing broad application across industries.

Applications span cosmetics and personal care (emollients, conditioners), medical devices and implants, construction (sealants, coatings), automotive and electronics (lubricants, potting compounds), and consumer goods (cookware, mold-making). Silicone elastomers provide abrasion and compression resistance; fluids and gels offer lubrication and cushioning.

Safety and environmental considerations: silicones are generally biocompatible and inert; medical-grade materials are used in implants. Some cyclic siloxanes have raised concerns about persistence and ecotoxicity, and many silicones are not readily biodegradable. Regulatory status depends on the specific compound and region.