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Moumoujus

STYRENE/MA COPOLYMER.

Valuable CAS 9011-13-6 / BINDING, EMULSION STABILISING, FILM FORMING

Styrene/MA Copolymer is a versatile polymer primarily recognized for its ability to form a non-penetrating, protective film on the skin, contributing to product efficacy and aesthetic finish. It also functions as a crucial emulsion stabilizer, ensuring the consistency and longevity of cosmetic formulations, particularly beneficial for managing oily skin.

Summary

Film-forming Emulsion Stabilizing Mattifying Opacifying Viscosity Increasing Dispersing Skin Conditioning

Science

Mechanism of Action

This copolymer operates by creating a flexible, protective film on the skin's surface. Its large molecular weight restricts skin penetration, ensuring its action remains superficial. For oily skin, it forms spherical particles that efficiently scatter light, delivering a visible mattifying effect and blurring minor imperfections. Additionally, it stabilizes emulsions and acts as a dispersant, enhancing the uniform distribution and stability of other active ingredients, such as those in sunscreens.

Research

Clinical Evidence

Low confidence
Effective range N/A
Optimal

N/A

Transparency

Dusting Analysis

Not commonly dusted

The Formula

Formulation

Solubility
Water
Optimal pH 5.5 – 8
0 7 14

Stability

Styrene/MA Copolymer is soluble in water-based alkaline solutions and polar organic solvents. The maleic anhydride form readily hydrolyzes in aqueous, basic environments to form soluble carboxylic acid/carboxylate groups. Optimal performance, particularly for membrane solubilization, is observed within a pH range of 5.5 to 8.0. Outside this range, specifically at low pH, the polymer can lose its charge and precipitate; sustained exposure to pH values between 8 and 10 may lead to membrane swelling or structural defects.

Conflicts

  • Oxidizing agents
  • Detergents (e.g., Tween 20)
  • Lecithin
  • Divalent cations (can cause precipitation if not at low salt levels)

Safety

Safety Profile

CIR Status
Safe as used
Sensitization risk Unknown

The CIR Expert Panel has deemed Styrene/MA Copolymer safe for use in cosmetics at current concentrations, attributing this to its substantial molecular size which limits percutaneous absorption. While residual styrene monomer is a consideration, levels found in cosmetic products are determined to be well below thresholds of concern. It's noted that the SCCS lacked sufficient data to assess nano forms of similar copolymers, but this distinction does not apply to the non-nano Styrene/MA Copolymer. Furthermore, it is listed by the FDA as a food contact substance.

Your Skin

Skin Compatibility

No Normal
No Dry
Yes Oily
No Sensitive
Irritancy Unknown
Comedogenicity Unknown

Our Assessment

Verdict

Valuable

Styrene/MA Copolymer is a valuable ingredient, particularly for oily skin formulations, offering film-forming, mattifying, and emulsion-stabilizing properties with a strong safety profile due to its limited skin penetration.

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