Triethoxysilylethyl Polydimethylsiloxyethylhexyl Dimethicone — INCI reference

What it is

Triethoxysilylethyl Polydimethylsiloxyethylhexyl Dimethicone is a complex silicone polymer combining triethoxysilyl reactive groups with a polydimethylsiloxane backbone and hexyl dimethicone side chains. It appears as a colorless to light-brown, transparent to slightly hazy viscous liquid. Its primary role in cosmetics is as a surface treatment agent for insoluble powders such as mineral pigments and sunscreen actives, rendering them hydrophobic and more evenly dispersible throughout the formulation and upon application to skin. This improved dispersibility contributes to smoother texture and more uniform coverage in finished products. As a dimethicone derivative, it also functions as a skin conditioning agent, forming a breathable occlusive film that helps reduce transepidermal water loss and imparts slip and softness. Its high molecular weight and chemically inert silicone structure mean it is poorly absorbed through skin, limiting systemic exposure.

Safety & warnings

As a high-molecular-weight silicone polymer, this ingredient is not significantly absorbed through intact skin, reducing systemic exposure concerns. No GHS hazard classifications, known allergens, or significant irritant properties have been identified in available safety data. The FDA recognizes dimethicone-class ingredients as safe skin protectants. No peer-reviewed toxicology studies specific to this compound have been published, but its structural similarity to well-characterized dimethicone polymers supports a favorable safety profile. Not approved for fragrance or flavor use.

Origin & sourcing

Synthesized through chemical modification of polydimethylsiloxane (dimethicone) polymers, incorporating triethoxysilyl reactive groups and hexyl side chains. It is a fully synthetic silicone compound produced via organosilicon chemistry, commercially available as a ready-to-use silicone fluid from Shin-Etsu Chemical Co., Ltd. (trade name KF-9909).

History

Reactive silicone fluids for cosmetic powder surface treatment were developed commercially in the late 20th century as demand grew for mineral sunscreen and color cosmetic formulations with improved texture. Shin-Etsu Chemical Co., Ltd. introduced KF-9909, based on this INCI, as part of its personal care silicone product line. The ingredient is listed in the EU CosIng database (COSING reference 59825) with the function of skin conditioning, reflecting its regulatory acceptance in cosmetic applications.

Questions everyone asks

What does Triethoxysilylethyl Polydimethylsiloxyethylhexyl Dimethicone do in sunscreen formulations?

It acts as a surface treatment agent for mineral pigments and UV filters such as zinc oxide and titanium dioxide, coating the particles to make them more hydrophobic and uniformly dispersible. This results in smoother application and more even distribution of the active ingredients across the skin.

Is this ingredient safe for sensitive skin?

Available data indicates it is generally well tolerated. High-molecular-weight silicone polymers like this one are poorly absorbed through skin and have no documented allergen associations.

Is this a natural or synthetic ingredient?

It is fully synthetic, produced through organosilicon chemistry to graft reactive triethoxysilyl and hexyl groups onto a polydimethylsiloxane backbone.

Which brand makes KF-9909, the commercial form of this ingredient?

KF-9909 is produced by Shin-Etsu Chemical Co., Ltd., a major Japanese specialty chemicals manufacturer. It is supplied as a ready-to-use silicone fluid for cosmetic powder surface treatment.