title: Cyclosiloxane
text: # 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 $(CH_3).$
  
  