Cetearyl Methicone is a silicone-based ingredient composed of cetearyl groups (a mixture of cetyl and stearyl alcohols) attached to a methicone base. It is widely used in cosmetics and personal care products for its emollient, conditioning, and film-forming properties. Cetearyl Methicone enhances the texture and feel of formulations, providing a smooth, non-greasy finish.

Chemical Composition and Structure

• Chemical Composition: Cetearyl Methicone is made by combining methicone, a type of silicone oil, with cetearyl alcohols (cetyl and stearyl alcohols). The combination results in a silicone compound with enhanced emollient and conditioning properties.

• Structure: The structure includes a dimethylsiloxane backbone (methicone) with attached cetearyl groups. The long-chain alcohols (cetearyl) contribute to its emollient properties and help improve the texture of cosmetic formulations.

Physical Properties

• Appearance: Typically a viscous, clear to slightly cloudy liquid or solid, depending on the formulation and temperature.
• Solubility: Insoluble in water but soluble in organic solvents. It is dispersible in various cosmetic formulations.
• pH: Stable across a wide range of pH values, making it suitable for various types of products.

Production Process

1. Silicone Polymerization: Dimethylsiloxane is polymerized to create the methicone base.
2. Alcohol Combination: Cetearyl alcohols are combined with the methicone base.
3. Purification: The resulting compound is purified to remove impurities and ensure safety and efficacy.
4. Formulation: It is incorporated into cosmetic formulations to improve product texture, provide a silky feel, and enhance overall performance.

Applications

• Medical: Not commonly used in medical applications.
• Cosmetics: Used in hair care products (such as conditioners and styling products) and skincare products (such as moisturizers and sunscreens). Provides a smooth, silky feel and helps in reducing frizz and improving the spreadability of the product.

INCI Functions:

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

CAS   227200-32-0

• Food: Not used in food products.

Environmental and Safety Considerations

Generally regarded as safe for topical application (1). However, like all silicones, it should be used in accordance with established guidelines to avoid potential allergic reactions or skin irritations. People with sensitive skin or allergies should exercise caution. It is important to ensure that the ingredient is sustainably sourced and free from harmful chemicals.

References__________________________________________________________________________

(1) Nair B; Cosmetic Ingredients Review Expert Panel. Final report on the safety assessment of stearoxy dimethicone, dimethicone, methicone, amino bispropyl dimethicone, aminopropyl dimethicone, amodimethicone, amodimethicone hydroxystearate, behenoxy dimethicone, C24-28 alkyl methicone, C30-45 alkyl methicone, C30-45 alkyl dimethicone, cetearyl methicone, cetyl dimethicone, dimethoxysilyl ethylenediaminopropyl dimethicone, hexyl methicone, hydroxypropyldimethicone, stearamidopropyl dimethicone, stearyl dimethicone, stearyl methicone, and vinyldimethicone. Int J Toxicol. 2003;22 Suppl 2:11-35. PMID: 14555417.

Abstract. Dimethicone is a fluid mixture of fully methylated linear siloxane polymers end-blocked with trimethylsiloxy units. Methicone is a linear monomethyl polysiloxane. The other dimethicones and methicones covered in this review are siloxane polymers of Dimethicone and Methicone. Most of these ingredients function as conditioning agents in cosmetic formulations at current concentrations of use of < or =15%. Clinical and animal absorption studies reported that Dimethicone was not absorbed following oral or dermal exposure. Dimethicone, Methicone, and Vinyldimethicone were not acutely toxic following oral exposure. No adverse reactions were found in rabbits following short-term dermal dosing with 6% to 79% Dimethicone, yet adverse effects were noted with a hand cream formulation containing 1% Dimethicone, suggesting something else in the preparation was toxic. Mice and rats were dosed for 90 days with up to 10% Dimethicone without adverse effect. Dimethicone did not produce adverse effects in acute and short-term inhalation-route studies, Methicone and Vinyldimethicone were negative in acute exposure studies using rats, but Hexyl Methicone was toxic to rats at 5 mg/L delivered in small particle (mean diameter of 0.29 micro) aerosols. Most dermal irritation studies using rabbits classified Dimethicone as a minimal irritant. Dimethicone (tested undiluted and at 79%) was not a sensitizer in four assays using mice and guinea pigs. It was not a sensitizer at 5.0% in a clinical repeated insult patch test using 83 panelists. Most ocular irritation studies using rabbits classified Dimethicone as a mild to minimal irritant. Dimethicone was tested in numerous oral-dose (using rats) and dermal-dose (using rats, rabbits, and monkeys) reproductive and developmental toxicity studies. In a few studies, treated males had significantly decreased body weight and/or decreased testes or seminal vesicles weights. No treatment-related adverse findings were noted in dosed pregnant females or fetuses. Dimethicone was negative in all genotoxicity assays. It was negative in both an oral (tested at 91%) and dermal (tested at an unknown concentration) dose carcinogenicity assay using mice. The Cosmetic Ingredient Review (CIR) Expert Panel considered it unlikely that any of these polymers would be significantly absorbed into the skin due to their large molecular weight. Although adverse effects were noted in one inhalation study with small aerosol particles, the expected particle sizes for cosmetic products would primarily be in the range of 60 to 80 micro, and less than 1% would be under 10 micro, which is an upper limit for respirable particles. Overall, the safety test data support the safety of these ingredients at the concentrations they are known to be used in cosmetic formulations. Accordingly, the CIR Expert Panel was of the opinion that Stearoxy Dimethicone, Dimethicone, Methicone, Amino Bispropyl Dimethicone, Aminopropyl Dimethicone, Amodimethicone, Amodimethicone Hydroxystearate, Behenoxy Dimethicone, C24-28 Alkyl Methicone, C30-45 Alkyl Methicone, C30-45 Alkyl Dimethicone, Cetearyl Methicone, Cetyl Dimethicone, Dimethoxysilyl Ethylenediaminopropyl Dimethicone, Hexyl Methicone, Hydroxypropyldimethicone, Stearamidopropyl Dimethicone, Stearyl Dimethicone, Stearyl Methicone, and Vinyldimethicone are safe as used in cosmetic formulations.