Phenyl trimethicone is a type of silicone that is used in cosmetics and personal care products as a texture enhancer, conditioning agent, sunscreen ingredient, and anti-foaming agent.
Phenyl trimethicone, also known as polyphenylmethylsiloxane, is a silicone fluid. Silicones are synthetic polymers with a backbone composed of repeating units of siloxane (elemental silicon and oxygen), which is why silicones may also be referred to as polysiloxanes. Often, the terms “silicone” and “silicon” are mistakenly used interchangeably, when they are actually quite different. Silicon is the 14th element on the periodic table and the second most abundant element in the earth’s crust, after oxygen. In contrast, silicones are always synthetically produced.
As a class, silicones improve the feel, appearance, and performance of cosmetic products. These ingredients act as silky moisturizers, conditioners, solvents, and delivery agents for other skin care ingredients. Silicones are able to help with skin redness and irritation due to their low surface tension, which enables them to spread easily across the surface of skin and form a protective covering.
Phenyl trimethicone is often used to enhance the texture of a cosmetic product. It contributes to a product’s silky feel on the skin and reduces the tackiness and stickiness in creams and lotions. Furthermore, phenyl trimethicone facilitates a uniform distribution of active ingredients on the skin surface. It has a drier finish than dimethicone, another common silicone used in skin care products.
Phenyl trimethicone is also used as a skin and hair conditioning agent because of its ability to increase hydration. It spreads easily over the skin and hair, forming a non-greasy and non-sticky invisible film that prevents the loss of moisture from the surface. This film still allows oxygen, nitrogen, and other important nutrients to pass through, but blocks water from evaporating. Ultimately, this leads to skin and hair that is hydrated and smooth.
The film formed by phenyl trimethicone not only protects the skin from moisture loss, but also prevents moisture penetration. This property is useful for the formulation of sun protection products. In addition, phenyl trimethicone can help dissolve UV-filters and increase the sun protection factor (SPF) of a product.
The last function of phenyl trimethicone is as an anti-foaming agent. This ingredient has the ability to inhibit the formation of foam even if the product is shaken.
The safety of phenyl trimethicone has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The Panel evaluated the scientific data and concluded that phenyl trimethicone was safe for use in cosmetics and personal care products.
Even though phenyl trimethicone and other silicones have been proven both safe and effective for cosmetic purposes, a multitude of rumors exist claiming they are unsafe for topical use. For instance, there are claims that silicones as a class can cause or worsen skin concerns, cause sensitization, and “suffocate” skin. However, these claims have not been proven in any published research.
To dispel these false claims, it’s first important to understand that the large molecular size of silicones prevents them from being absorbed by the skin. If a substance cannot penetrate the skin, it cannot react with cells of the immune system. Thus, silicones are not allergens. Additionally, claims that silicones can bioaccumulate (build up) in our bodies are also false. Once again, this is because their large size prevents them from penetrating the skin. If silicones cannot penetrate the skin, they certainly cannot pass through cell membranes, a key requirement for bioaccumulation.
Lastly, it is incorrect to say that the film formed by silicones somehow “suffocates” the skin. As mentioned above, the soft, invisible film that phenyl trimethicone and other silicones form after topical application allows oxygen and other gases to pass through. Furthermore, the film does not block the natural skin secretion. Thus, the skin can still “breathe” after topical application of a product containing silicones.
References: Unisil, “Technical Data Sheet on Phenyl Trimethicone”, Cosmetics Info, “Phenyl Trimethicone”.