Methicone is a type of silicone that is used in cosmetics and personal care products for its smooth and silky feel. It is a derivative of dimethicone, featuring a similar chemical structure but with a different modification that enhances its compatibility with various formulations. Methicone is valued for its ability to reduce friction, improve spreadability, and enhance the sensory experience of products.
Chemical Composition and Structure
Chemical Composition: Methicone is composed of dimethicone (polydimethylsiloxane) with additional modifications that alter its physical properties.
Structure: It typically has a siloxane backbone with methyl groups attached. The modification may include variations in the length and structure of the siloxane chains, affecting its properties and performance.
Physical Properties
- Appearance: Generally appears as a clear, colorless liquid.
- Solubility: Insoluble in water but soluble in organic solvents and oils. It is compatible with other silicones and oils.
- pH: Methicone is stable across a wide range of pH levels, making it versatile for various formulations.
Production Process
Methicone is synthesized through the polymerization of siloxane units with one of the bonds replaced by a methyl group. This process creates a stable silicone that can be used in various cosmetic formulations to improve texture and provide surface protection.
- Silicone Polymerization: The base dimethicone is produced through the polymerization of siloxane monomers.
- Modification: Dimethicone is modified to produce Methicone, often by altering the length and branching of the siloxane chains.
- Purification: The final product is purified to ensure it meets quality and safety standards.
- Formulation: Methicone is incorporated into cosmetic and personal care products to enhance texture and performance.
Applications
- Medical: Not commonly used in medical applications.
- Cosmetics: Used in a variety of products including lotions, creams, shampoos, conditioners, and sunscreens for its smoothing and conditioning properties.
INCI Functions:
Antistatic agent. Static electricity build-up has a direct influence on products and causes electrostatic adsorption. The antistatic ingredient reduces static build-up and surface resistivity on the surface of the skin and hair.
Skin conditioning agent - Emollient. Emollients have the characteristic of enhancing the skin barrier through a source of exogenous lipids that adhere to the skin, improving barrier properties by filling gaps in intercorneocyte clusters to improve hydration while protecting against inflammation. In practice, they have the ability to create a barrier that prevents transepidermal water loss. Emollients are described as degreasing or refreshing additives that improve the lipid content of the upper layers of the skin by preventing degreasing and drying of the skin. The problem with emollients is that many have a strong lipophilic character and are identified as occlusive ingredients; they are oily and fatty materials that remain on the skin surface and reduce transepidermal water loss. In cosmetics, emollients and moisturisers are often considered synonymous with humectants and occlusives.
Skin conditioning agent. It is the mainstay of topical skin treatment as it has the function of 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 that can be added in the formulation.
Environmental and Safety Considerations
Generally regarded as safe for topical application (1). However, like all silicones, it should be used according to established guidelines to avoid potential allergic reactions or skin irritations. Individuals with sensitive skin or allergies should be cautious. It is important to ensure that the ingredient is sustainably sourced and free from harmful chemicals.
Allergic Reactions
Allergic reactions to Methicone are very rare, as it is a non-reactive and hypoallergenic ingredient. However, as with any cosmetic ingredient, it is recommended to perform a patch test before using new products to rule out individual sensitivities.
Toxicity and Carcinogenicity
It is widely used in cosmetics and personal care products and is considered safe at recommended concentrations. It does not accumulate in the body and is well-tolerated.
Environmental and Safety Considerations
Methicone, like other silicones, is chemically stable and does not degrade easily in the environment. While it poses no immediate risk, silicones can accumulate over time, so using Methicone-containing products responsibly and considering more eco-friendly alternatives when possible is advised.
Regulatory Status
Methicone is approved for use in cosmetics by regulatory bodies such as the European Union and the Food and Drug Administration (FDA) in the United States. It is regulated to ensure safe use in cosmetic products.
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.
Methicone 
