This volatile silicone serves as a lightweight emollient that imparts a distinctive “silk” feel to cosmetic formulations. Unlike heavier oils, the fluid evaporates quickly after application, functioning primarily as a temporary carrier for other active substances. Its low surface tension allows for the seamless spread of pigments and sun filters across the skin surface.
- INCI Name:
- Cyclopentasiloxane
- Chemical/Scientific Name:
- Decamethylcyclopentasiloxane
- Common Aliases:
- D5, Cyclic Dimethylsiloxane Pentamer
| Category: | Softeners |
| Source Origin: | Synthetic |
| Comedogenic Rating: | 0 |
| Primary Industries: | Skincare, Color Cosmetics, Hair Care |
| Solubility: | Oil, Silicones, Isododecane |
At a Glance: Properties & Effects
| Texture Enhancement | |
| Soothing/Calming | |
| Barrier Repair | |
| Irritation Risk | |
| Comedogenicity |
- Primary Benefits: Eliminates formula tackiness, improves product spreadability, provides a velvet-like skin finish, and facilitates the even distribution of UV filters.
- Potential Risks: Environmental bioaccumulation in aquatic systems, potential for future regulatory restrictions in leave-on products.
Biological Action & Cosmetic Profile
Molecular weight and a specific cyclic structure prevent this substance from penetrating the viable layers of the epidermis. Instead, the fluid resides on the stratum corneum, where it fills in textural irregularities to create a temporarily smooth surface. By lowering the surface tension of a formula, it ensures that ingredients like Aqua and oils mix more effectively during application, preventing the “drag” often associated with high-viscosity creams.Evaporation plays a critical role in the user experience of silicone-based products. Because the molecule is volatile, it transitions from liquid to gas at body temperature. This process allows the product to feel “wet” and spreadable for a few seconds before setting into a dry, non-greasy film. In hair care, this mechanism allows the silicone to coat the hair shaft for detangling purposes without leaving behind a heavy, weighted residue after the hair dries.Texture modification remains the primary reason chemists include this compound in high-performance serums. It acts as a solvent for heavier silicones like Dimethicone or Dimethiconol. By thinning these viscous polymers, the formulator can achieve a product that feels luxurious and expensive without the stickiness inherent to long-chain silicone gums.
Broader Applications & Origins
Synthetic production involving the hydrolysis of dimethyldichlorosilane yields this high-purity cyclic silicone. While silicones are derived from the natural element silicon, they undergo extensive chemical processing to achieve their final functional form. This specific pentamer is often paired with Cyclohexasiloxane to create “cyclomethicone” blends, which offer a staggered evaporation rate for better control during the application of foundations and sunscreens.Environmental considerations have shifted the way this material is utilized in the global market. Unlike linear silicones, cyclic varieties have come under scrutiny by the European Chemicals Agency (ECHA) due to their persistence in the environment. While the cosmetic performance is difficult to replicate with natural plant oils, many brands are moving toward volatile alkanes like Isododecane as a more biodegradable alternative.
Routine Integration
- Synergies: Works exceptionally well with Dimethicone for long-wear textures, Silica for oil control, and physical UV filters like Zinc Oxide to prevent clumping.
Clinical Consensus & Safety
The Scientific Committee on Consumer Safety (SCCS) and the Cosmetic Ingredient Review (CIR) have both concluded that this ingredient is safe for human health when used in cosmetic concentrations. It is non-sensitizing and does not cause significant skin irritation even in sensitive populations. However, the European Union has restricted its use in wash-off products (such as shampoos and cleansers) to a maximum concentration of 0.1% by weight. This restriction, effective since 2020, is strictly an environmental measure intended to reduce the accumulation of the substance in wastewater and aquatic ecosystems, rather than a reflection of human toxicity.
Is cyclopentasiloxane the same as cyclomethicone?
Cyclomethicone is a generic term that usually refers to a blend of cyclic silicones, including D4, D5 (cyclopentasiloxane), and D6. Most modern “cyclomethicone” raw materials are primarily composed of D5, as D4 (cyclotetrasiloxane) is largely phased out due to safety concerns.
Does it clog pores or cause acne?
No, the molecular structure is too large to enter the pore, and it is chemically inert. It holds a comedogenic rating of 0, making it an ideal choice for oily or acne-prone skin types that require a “dry-touch” moisturizer.
Why is it being removed from some products?
Removal is primarily driven by environmental regulations in the UK and EU. Because the molecule does not break down easily in the water supply, brands are transitioning to more ecologically friendly alternatives to comply with “Clean Beauty” standards and regional laws.