Octamethylcyclotetrasiloxane

Octamethylcyclotetrasiloxane (CAS 556-67-2), commonly abbreviated as D4, is a cyclic siloxane monomer used as a key building block in silicone polymer synthesis.

Where is Octamethylcyclotetrasiloxane used?

• Coatings: reactive intermediate and processing aid
• Personal care: carrier and emollient base in hair conditioners and skin creams
• Polymer manufacturing: reactive intermediate and processing aid
• In silicone elastomer and sealant production, D4 undergoes ring-opening polymerization to produce polydimethylsiloxane chains of controlled molecular weight.
• Industrial coatings and release liners: surface modifier and crosslinking precursor, improving substrate wetting and film durability
• Adhesive and sealant manufacturing: reactive diluent to control viscosity and cure behavior in silicone formulations

Good to know: D4 is subject to concentration restrictions in certain jurisdictions, requiring careful formulation and adherence to local safety standards. Buyers should confirm regulatory compliance status for their target market, particularly for personal care applications.

Commercial specifications

• Purity typically 99% or higher
• Drum and IBC quantities
• Bulk tanker options for high-volume requirements