Cyclosiloxane
# Cyclosiloxane

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.

## Octamethylcyclotetrasiloxane (D4)

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 $(CH_3).$

## Decamethylcyclopentasiloxane (D5)

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 $(CH_3).$ 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.

## 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 $(CH_3).$

