Octamethylcyclotetrasiloxane

Octamethylcyclotetrasiloxane (CAS 556-67-2) is a cyclic silicone monomer supplied under trade designations including KF-994, CO-9810, UC 7207, VS 7207, and SF 1173. It carries no assigned E-code and is classified under HS code 29319090 within the silicones and silicates category.

In personal care formulations, it functions as a volatile carrier and emollient, spreading active ingredients across skin or hair before evaporating cleanly without residue. In silicone polymer production, it serves as a reactive monomer and crosslinker, undergoing ring-opening polymerization to build polydimethylsiloxane networks used in adhesives, sealants, and elastomers.

This material is available in technical and cosmetic grades and is subject to REACH registration requirements within the EU. Suppliers typically offer it in drum and IBC packaging. Procurement teams should note its SVHC candidate list status and verify current authorization requirements before specifying it in new formulations.