silikoon

Silikoon, commonly referred to in English as silicone, is a family of polymers and resins characterized by a backbone of alternating silicon and oxygen atoms, known as siloxanes, with organic groups attached to silicon. This combination gives materials that are flexible, chemically resistant and thermally stable.

The chemical composition includes repeating –Si–O– units with various side chains such as methyl or phenyl. Based on physical properties, silicone materials are commonly classified as elastomers (silicone rubber), fluids (silicone oil), resins and gels. Specialty grades include room-temperature vulcanizing (RTV) silicones and condensation-cured variants.

Key properties: wide operating temperature range, typically from about -55 to +250 C depending on grade; remarkable flexibility at low temperatures; high electrical insulation; chemical inertness; low surface energy, leading to non-stick and water-repellent surfaces; biocompatibility in many forms.

Synthesis involves hydrolysis and polycondensation of organosilicon precursors or ring-opening polymerization of cyclic siloxanes to form polydimethylsiloxane (PDMS) and related polymers. The organic side groups determine properties such as hardness, flexibility and resistance to heat and chemicals.

Applications include construction sealants and adhesives; cookware coatings and bakeware; medical devices and implants; consumer products like kitchen utensils; electronic potting and encapsulation; lubricants and greases; automotive and aerospace components.

Safety and environment: silicone materials are generally regarded as low-toxicity and chemically inert; however, additives or degradation products may pose risks in certain uses. Recycling and disposal depend on the grade; most silicones are not biodegradable and can persist in the environment.