Silikonopolymerer

Silikonopolymerer, commonly called silicone polymers, are a family of polymers based on a silicon-oxygen backbone with organic substituents attached to silicon. The best-known member is polydimethylsiloxane (PDMS).

Chemically, the repeating unit is typically written as [-Si(-R)2-O-]n, where R are organic groups such as methyl, phenyl, or vinyl. The polymers can be linear or crosslinked to form elastomers, resins, or gels. They are produced by methods including ring-opening polymerization of cyclic siloxanes (for example D4, D5) and by condensation or hydrolysis of silane precursors.

Key properties include thermal stability, a broad service temperature range, chemical inertness, low surface energy, good dielectric strength, and often optical clarity. Many grades are biocompatible and stable in contact with water and many chemicals, making them suitable for medical devices, cosmetics, and electronics.

Processing methods vary by form. Crosslinking can occur via addition curing (hydrosilylation), peroxide curing, or condensation reactions. Room-temperature vulcanizing (RTV) silicones cure at ambient conditions, enabling sealants, potting compounds, and encapsulants for electronics and consumer products.

Applications span sealants and adhesives in construction, lubricants and greases, coatings and impregnations, medical implants and devices, cosmetics, automotive components, and food-contact materials in some grades.

Limitations include often weaker adhesion to certain substrates without primers, potential permeability to gases and solvents, and higher cost compared with some hydrocarbon polymers. Environmental considerations center on energy use in production and endings; recycling is limited for crosslinked grades.