Acrylates/Stearyl Acrylate/Dimethicone Methacrylate Copolymer is a high-performance, silicone-graft film former. It is engineered to provide exceptional water resistance, long-wear properties, and a non-tacky, smooth finish in topical formulations.
- INCI Name:
- Acrylates/Stearyl Acrylate/Dimethicone Methacrylate Copolymer
- Chemical/Scientific Name:
- Grafted copolymer consisting of stearyl acrylate, dimethicone methacrylate, and one or more monomers of acrylic acid or methacrylic acid.
- Common Aliases:
- Silicone Acrylate Copolymer, KP-541 (Trade Name), KP-545 (Solution in Cyclopentasiloxane)
| Category: | Texture Enhancers |
| Source Origin: | Synthetic |
| Comedogenic Rating: | 0 |
| Primary Industries: | Color Cosmetics, Sun Care, Skincare |
| Solubility: | Oil and Silicone Soluble |
At a Glance: Properties & Effects
| Texture Enhancement: | |
| Water Resistance: | |
| Formula Stability: | |
| Irritation Risk: |
- Primary Benefits: Superior film formation, extended wear-time for pigments and UV filters, sebum resistance, and a silky skin feel.
- Potential Risks: Requires dedicated oil-based cleansers for removal; negligible irritation risk for most skin types.
Biological Action & Cosmetic Profile
This ingredient functions as a hybrid polymer that leverages the distinct physical properties of both acrylates and silicones. The acrylate backbone provides structural integrity and adhesion to the skin surface, creating a durable, flexible matrix. Attached to this backbone are stearyl chains and Dimethicone side chains. The stearyl groups ensure compatibility with traditional cosmetic oils and waxes, while the silicone components lower the surface tension, resulting in a smooth spread and a hydrophobic (water-repellent) barrier.
Film formation is the primary mechanism of action. Once the volatile carrier—typically Isododecane or a cyclomethicone—evaporates, the polymer leaves behind a cohesive layer. This layer prevents “migration” or “bleeding” of color cosmetics and keeps active ingredients like sunscreens in place, even when exposed to perspiration or water. Unlike pure acrylate polymers, which can feel tight or brittle, the grafted silicone units provide plasticization, allowing the film to move with the skin without cracking.
Stability and rheology are also influenced by this copolymer. In emulsions, it acts as a secondary stabilizer by increasing the viscosity of the oil phase and preventing the coalescence of droplets. Because it is resistant to both water and sebum, it is highly effective in “transfer-proof” and “smudge-proof” marketing claims, particularly for long-wear foundations, mascaras, and liquid lipsticks.
Broader Applications & Origins
Synthetic synthesis of this copolymer allows for precise control over the ratio of silicone to acrylate, tailoring the “softness” or “hardness” of the resulting film. It was originally developed to overcome the limitations of standard film formers, which often felt tacky or heavy on the skin. By incorporating the Dimethicone methacrylate monomer, chemists successfully balanced durability with the desirable “slip” associated with silicone technology.
Routine Integration
- Synergies: High compatibility with volatile solvents like Isododecane and Cyclopentasiloxane. It works effectively alongside hydrophobic powders such as Silica to enhance matte finishes and oil control.
- Conflicts: No known biochemical conflicts; however, it may exhibit poor solubility in highly polar, water-based serums unless pre-emulsified.
Clinical Consensus & Safety
The Cosmetic Ingredient Review (CIR) Expert Panel has evaluated the safety of acrylates copolymers, including silicone-grafted variants. These polymers are characterized by a high molecular weight, which prevents them from penetrating the stratum corneum. Consequently, they do not pose a risk of systemic toxicity. Clinical patch testing indicates that Acrylates/Stearyl Acrylate/Dimethicone Methacrylate Copolymer is a non-sensitizer and non-irritant at standard cosmetic concentrations (typically 1–10%). Regulatory bodies, including CosIng, authorize its use without specific restricted concentration limits, classifying it as a safe aesthetic enhancer.
Is this ingredient safe for acne-prone skin?
Yes. Due to its large molecular size and non-comedogenic nature, it does not clog pores. It creates a breathable film that allows for gas exchange while remaining resistant to liquid water and sebum.
How do I remove products containing this copolymer?
Because the film is designed to be water and sebum resistant, a standard water-based cleanser may be insufficient. An oil-based cleanser, micellar water with high surfactant load, or a dedicated makeup remover is recommended to dissolve the polymer matrix effectively.