Trisiloxane is a type of silicone-based compound widely used in cosmetic and personal care products for its lightweight, emollient, and spreading properties. It is valued for its ability to enhance the spreadability of formulations, providing a smooth, non-greasy feel on the skin or hair. Trisiloxane is commonly found in products such as foundations, sunscreens, hair serums, and other leave-on skincare products due to its ability to improve texture, promote even application, and enhance the performance of active ingredients. It evaporates quickly, leaving a silky finish on the skin without residue.

Chemical Composition and Structure
Trisiloxane is a linear siloxane compound consisting of three silicon-oxygen (Si-O) bonds. Its chemical structure includes silicon atoms connected by oxygen atoms, with organic groups attached to the silicon. This molecular arrangement gives Trisiloxane its ability to act as a carrier for other ingredients, helping them spread evenly across the skin or hair. The lightweight nature of the compound makes it ideal for products where a smooth, non-oily finish is desired.

Physical Properties
Trisiloxane typically appears as a clear, colorless, and odorless liquid. It is known for its low viscosity and ability to spread quickly and evenly on the skin or hair. The compound is volatile, meaning it evaporates after application, leaving no greasy or heavy residue. This property makes it a popular ingredient in formulations that require a lightweight, silky texture, such as in foundations, sunscreens, and serums.

Production Process
The production of Trisiloxane involves the polymerization of siloxane monomers to create the desired siloxane structure with specific molecular weight and volatility. Key steps include:

1. Synthesis: Siloxane monomers undergo controlled polymerization, forming a linear structure with three silicon-oxygen units.

2. Modification: The siloxane chain is often modified with organic side groups to enhance compatibility with other ingredients in cosmetic formulations.

3. Purification: The resulting Trisiloxane compound is purified to remove impurities and ensure a high-quality, stable product.

4. Formulation: Once purified, Trisiloxane is incorporated into cosmetic formulations to improve texture, spreadability, and product performance.

Applications

• Skincare: Trisiloxane is commonly used in leave-on skincare products such as serums, lotions, and creams to provide a lightweight, silky feel. Its volatile nature allows it to spread evenly on the skin, creating a smooth, non-greasy finish. It also helps deliver active ingredients more effectively by promoting even application.

• Makeup: In makeup formulations, especially foundations and primers, Trisiloxane enhances spreadability and provides a silky, even texture. It helps the product glide smoothly over the skin and creates a natural, flawless finish without feeling heavy.

• Sunscreens: Trisiloxane is used in sunscreens to help distribute UV filters evenly across the skin, improving the product's effectiveness. Its quick-drying and non-greasy properties make it ideal for sun care formulations.

• Haircare: In haircare products like serums and conditioners, Trisiloxane provides shine and smoothness, helping to reduce frizz and improve manageability without weighing the hair down.

INCI Functions:

Antifoaming agent. The constituent factors for foam stabilisation are the concentration of nanoparticles and hydrophobicity. Foam, even when used in separation operations such as fractionation or flotation, can cause a decrease in density and a deterioration in quality in cosmetic products. The defoaming agent (non-polar oil, silicone oils, hydrophobic solid particles or mixtures of both) is strongly influenced by viscosity and, to an almost directly proportional extent, concentration. However, defoamers can carry an irreversible source of contamination.

Skin conditioning agent. It is the mainstay of topical skin treatment by restoring, increasing or improving skin tolerance to external factors, including melanocyte tolerance (1). The most important function of the conditioning agent is to prevent skin dehydration, but the subject is rather complex and involves emollients and humectants.

Environmental and Safety Considerations

Trisiloxane is generally considered safe for use in cosmetic and personal care products. It is non-irritating and non-sensitizing when applied to the skin or hair. However, as with many silicone-based ingredients, it is not biodegradable, which raises environmental concerns regarding its accumulation in aquatic environments. 

The use of trisiloxane surfactants, which are often used as co-formulants in pesticides, may be a minor challenge for pollinating insects (2).

The increasing interest in sustainability is driving research into eco-friendly alternatives or improved waste management practices for silicone-derived compounds. 

Molecular Formula  C₈H₂₄O₂Si₃

Molecular Weight  236.53 g/mol

CAS     107-51-7

UNII    9G1ZW13R0G

EC Number  203-497-4

DTXSID9040710

Synonyms:

Trisiloxane, octamethyl-

Octamethyltrisiloxane

References__________________________________________________________________________

(1) Karasiewicz J, Krawczyk J. Thermodynamic Analysis of Trisiloxane Surfactant Adsorption and Aggregation Processes. Molecules. 2020 Dec 1;25(23):5669. doi: 10.3390/molecules25235669.

Abstract. The trisiloxane polyether surfactant (3-[3-(hydroxy)(polyethoxy)propyl]-1,1,1,3,5,5,5 -heptamethyltrisiloxane) (TS-EO12) was successfully synthesized by a hydrosilylation reaction in the presence of Karstedt catalyst. The structural analysis of the surfactant was done by 1H-NMR, 13C-NMR, 29Si-NMR and FT-IR analysis. In addition the thermal stability of TS-EO12 was studied by the thermogravimetric measurements. On the one hand the surface properties of TS-EO12 at the water-air interface were investigated by surfactant aqueous solutions surface tension measurements carried out at 293 K, 303 K and 313 K, and on the other the aggregation properties were analyzed based on the solubilization properties of TS-EO12 aggregates at different temperatures. On the basis of the obtained thermodynamic parameters of adsorption and micellization of studied surfactant the temperature impact on its surface and volume properties were deduced. It was proved that the tendency of the studied surfactant molecules to adsorb at the water-air interface and to form micelles weakens with decreasing temperature. It was also concluded that the structure of the adsorption layer changes with temperature. Optical microscopy measurements were used for the TS-EO12 micelle morphology determination.

(2) Fine JD, Cox-Foster DL, Moor KJ, Chen R, Avalos A. Trisiloxane Surfactants Negatively Affect Reproductive Behaviors and Enhance Viral Replication in Honey Bees. Environ Toxicol Chem. 2024 Jan;43(1):222-233. doi: 10.1002/etc.5771.

Collins JK, Jackson JM. Application of a Screening-Level Pollinator Risk Assessment Framework to Trisiloxane Polyether Surfactants. Environ Toxicol Chem. 2022 Dec;41(12):3084-3094. doi: 10.1002/etc.5479.