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. It functions as a reactive intermediate and processing aid across coatings, personal care, and polymer manufacturing. In silicone elastomer and sealant production, D4 undergoes ring-opening polymerization to produce polydimethylsiloxane chains of controlled molecular weight. Personal care formulators use it as a carrier and emollient base in hair conditioners and skin creams.

In these applications, it delivers a smooth, non-greasy skin feel that supports product aesthetics. In industrial coatings and release liners, D4 acts as a surface modifier and crosslinking precursor, improving substrate wetting and film durability. Adhesive and sealant manufacturers also use it as a reactive diluent to control viscosity and cure behavior in silicone formulations. D4 is supplied as a clear, low-viscosity liquid in drum and IBC quantities for industrial buyers.

Bulk tanker options are available for high-volume requirements. Standard supply grades include technical and polymer-grade specifications, with purity typically at 99% or higher to ensure consistent performance in chemical synthesis. Buyers should confirm regulatory compliance status for their target market, particularly for personal care applications. D4 is subject to concentration restrictions in certain jurisdictions, requiring careful formulation and adherence to local safety standards.