Silicones

Synonym(s)

engl.: silicone; Organosiloxanes; Polymers of siloxanes; poly(organo)siloxanes; Polysiloxanes; Silicones; Siloxanes

Definition
This section has been translated automatically.

Silicones, also known as siloxanes, are a group of synthetic polymers based on silicon. Due to their structure, silicones are similar to carbon compounds. The carbon in silicones is replaced by silicon. Silicones thus occupy an intermediate position between inorganic and organic compounds.

Classification
This section has been translated automatically.

The following groups are distinguished:

Linear polysiloxanes

Branched polysiloxanes

Cyclic polysiloxanes

Crosslinked polysiloxanes. Here chain- or ring-shaped molecules are linked to form planar or three-dimensional networks.

Properties and use

Silicones are heat resistant, hydrophobic, dielectric and are physiologically well tolerated, which is why they are used for skin protection, cosmetic skin care and plastic surgery. Low-viscosity linear silicones like the dimethicone are used against meteorism and flatulence as well as in endoscopy.

According to their fields of application, the silicones can be used in:

Silicone oils
Silicone Greases
Silicone resins
Silicone rubbers

...to divide them up.

Silicone oils, which are processed to emulsions, antifoams, pastes, greases, generally consist of linear poly(dimethylsiloxanes). They have a polycondensation degree of n=400-1200.

General information
This section has been translated automatically.

The silicon atoms are linked to linear molecular chains via oxygen atoms or they are linked in a reticular fashion. The free valencies of the silicon atoms are saturated with organic residues.

The "Si-O-Si bonds" on which the silicones are based are called siloxane bonds. Silicones are therefore polyorganosiloxanes. A linear polymer with the general formula (CH3)3-Si-O-[(CH3)2Si-O]n-Si-(CH3)3 is called poly(dimethylsiloxane). The international non-proprietary name of the compound is dimetticone.

Its physical properties (liquid = silicone oil; semi-solid = silicone resin) depend on the length of the molecular chains or its degree of cross-linking.

Note(s)
This section has been translated automatically.

Silicones in cosmetics: In the past, liquid silicones were used in cosmetics for the injection of wrinkles. This procedure is obsolete today. Liquid silicone (silicone oil) is used in cosmetic products as synthetic oil components. They act as moisturizers, solvents and viscosity regulators (increase or decrease the viscosity of cosmetic products).

Silicones in medicine: Artificial heart valves, pacemakers, cavernous body implants are also made of silicones. Silicone bags filled with silicone gel are used for silicone breast implants.

Silicones in dentistry: Highly cross-linked silicones are indispensable for taking exact impressions of the teeth and jaws to produce precision models.