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Cyclosiloxane

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Cyclosiloxanes are a class of silicone material. They are volatile and often used as a solvent. The three main commercial varies are octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6). They evaporate and degrade in air under sunlight.[1]

Octamethylcyclotetrasiloxane (D4)

Chemical structure of octamethylcyclotetrasiloxane
Main article: octamethylcyclotetrasiloxane

The octamethylcyclotetrasiloxane silicone liquid has no odor and consists of four repeating units of silicon (Si) and oxygen (O) atoms in a closed loop giving it a circular structure. Each silicon atom has two methyl groups attached (CH3).

Decamethylcyclopentasiloxane (D5)

Chemical structure of decamethylcyclopentasiloxane
Main article: decamethylcyclopentasiloxane

Decamethylcyclopentasiloxane silicone liquid has no odor and consists of five repeating units of silicon (Si) and oxygen (O) atoms in a closed loop giving it a circular structure. Each silicon atom has two methyl groups attached (CH3). Typically it is used as an ingredient in antiperspirant, skin cream, sun protection lotion and make-up. With a low surface tension of 18 mN/m this material has good spreading properties.[2]

Dodecamethylcyclohexasiloxane (D6)

The dodecamethylcyclohexasiloxane silicone liquid has no odor and consists of six repeating units of silicon (Si) and oxygen (O) atoms in a closed loop giving it a circular structure. Each silicon atom has two methyl groups attached (CH3). CASRN: 540-97-6. D6 is also contained under the CAS No. (69430-24-6 ) which is associated with the names cyclopolydimethylsiloxane, cyclopolydimethylsiloxane (DX), cyclosiloxanes di-Me, dimethylcyclopolysiloxane, polydimethyl siloxy cyclics, polydimethylcyclosiloxane, cyclomethicone and mixed cyclosiloxane.[3]

See also

Literature

  • Cyclosiloxanes (pdf-file), Materials for the December 4-5, 2008 Meeting of the California Environmental Contaminant Biomonitoring Program (CECBP) Scientific Guidance Panel (SGP)

References

  1. ^ "Cyclosiloxanes Information Center - What are Cyclosiloxanes?". www.cyclosiloxanes.org.[dead link‍]
  2. ^ "XIAMETER™ PMX-0245 Cyclopentasiloxane Technical Data Sheet" (PDF). Dow.
  3. ^ Existing Substances Evaluation. Substance Profile for The Challenge. Decamethylcyclopentasiloxane (D5). CAS No. 541-02-6. Environment Canada. 2007
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