Methylpolysiloxane is a high-performance silicone polymer that functions as a powerful occlusive and skin protectant. It forms a breathable, non-greasy barrier on the skin’s surface to lock in moisture and protect against environmental irritants.
- INCI Name:
- Dimethicone
- Chemical/Scientific Name:
- Polydimethylsiloxane (PDMS)
- Common Aliases:
- Dimethylpolysiloxane, Dimethyl Silicone Oil, E900
| Category: | Softeners |
| Source Origin: | Synthetic |
| Comedogenic Rating: | 1 |
| Primary Industries: | Cosmetics, Pharmaceuticals, Food Processing |
| Solubility: | Insoluble in water; soluble in organic solvents and other silicones |
At a Glance: Properties & Effects
| Texture Enhancement | |
| Barrier Repair | |
| Hydration/Moisture | |
| Irritation Risk |
Primary Benefits:
- Creates a silk-like texture and eliminates the “tackiness” of heavy formulations.
- Prevents transepidermal water loss (TEWL) by forming a physical, breathable film.
- Acts as a skin protectant against friction and contact with household chemicals.
Potential Risks:
- May cause product pilling if used in excessive concentrations without proper emulsification.
- Rare reports of sensitivity in individuals with extremely reactive skin.
Biological Action & Cosmetic Profile
This organosilicon compound consists of fully methylated linear siloxane polymers. Unlike many plant oils, it does not penetrate the deeper layers of the epidermis; instead, its large molecular structure allows it to remain on the skin surface. By filling in microscopic gaps between skin cells, the polymer provides an immediate smoothing effect and improves the overall “slip” of cosmetic products during application.Occlusive properties define this material’s physiological role. It creates a semi-permeable film that mimics the natural lipid barrier, allowing oxygen to pass through while significantly slowing the evaporation of internal water. Clinical studies demonstrate that this film effectively shields the stratum corneum from external irritants like sodium lauryl sulfate, making it a cornerstone ingredient in therapeutic barrier creams and medical-grade ointments.Formulations benefit significantly from the polymer’s ability to suppress foam and reduce greasiness. It is frequently paired with Petrolatum or Glycerin to balance their heavy textures. Furthermore, the chemical inertness of this silicone ensures it does not react with other active ingredients, maintaining formula stability over time.
Broader Applications & Origins
While widely recognized for its cosmetic utility, this polymer is a staple in the pharmaceutical and food sectors. In medicine, it is used in anti-flatulent medications and as a coating for surgical instruments to reduce friction. In the food industry, it serves as an anti-foaming agent to prevent splattering in frying oils. The manufacturing process involves the hydrolysis of dimethyldichlorosilane, resulting in a pure, stable fluid that can be adjusted for varying viscosities.
Routine Integration
Synergies:
- Humectants: Works exceptionally well with Hyaluronic Acid or Glycerin, as it “seals” the water these ingredients draw into the skin.
- Sunscreen Filters: Often used with Zinc Oxide or Titanium Dioxide to improve mineral dispersion and water resistance.
- Powders: Pairs with Silica or Mica in makeup to provide a smooth, velvety finish.
Conflicts:
- Universally compatible; no known chemical conflicts with common skincare actives.
Clinical Consensus & Safety
Dermatological assessments from the Cosmetic Ingredient Review (CIR) Expert Panel and the Scientific Committee on Consumer Safety (SCCS) consistently classify this polymer as safe for topical use. It is non-comedogenic and non-sensitizing, with a safety profile so robust that the FDA approves it as an over-the-counter skin protectant. Clinical trials have repeatedly shown that it does not exacerbate acne, despite the common misconception that silicones “suffocate” the skin.
Does Methylpolysiloxane cause acne or clog pores?
No. Clinical testing indicates it has a comedogenic rating of 1, meaning it is highly unlikely to clog pores. Its molecular size is too large to enter the pore, and its film is breathable, allowing sweat and sebum to escape.
Is it safe for sensitive or eczema-prone skin?
Yes. Because it is chemically inert and non-reactive, it is one of the most recommended ingredients for sensitive skin. It provides a protective layer that prevents further irritation while the skin barrier heals.
How does it differ from natural oils?
Natural oils often provide nutrients but can be unstable and feel greasy. This silicone provides superior occlusive protection and texture enhancement without the risk of oxidation or a heavy, sticky residue.