Science
Mechanism of Action
This copolymer operates by forming a cohesive film on the skin's surface, which aids in binding other ingredients together and can contribute to the product's aesthetic by providing an opacifying effect. Its high molecular weight prevents dermal absorption, ensuring its action is superficial. It also contributes to product viscosity, acting as an oil thickener or gelling agent in certain formulations.
Research
Clinical Evidence
Low confidenceN/A
Transparency
Dusting Analysis
The Formula
Formulation
Stability
This oil-soluble copolymer demonstrates good compatibility with substances like paraffin wax and ethylene vinyl acetate. Achieving complete dissolution in oil, particularly for related variants, may necessitate heating to approximately 100-110 degrees Celsius.
Safety
Safety Profile
The Cosmetic Ingredient Review (CIR) Expert Panel has determined this copolymer, alongside 34 related styrene and vinyl-type styrene copolymers, to be safe for use in cosmetics. Its large molecular structure prevents skin penetration, minimizing systemic exposure. Residual monomer levels, such as styrene and 1,3-butadiene, are typically maintained below 500 ppm in raw materials, ensuring extremely low levels in finished products, well below concern thresholds. However, the SCCS has not evaluated nano-forms of related copolymers due to insufficient data. There is a documented instance of cross-reactivity in a patient with a pre-existing styrene allergy, linked to methylstyrene.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Styrene/Methylstyrene Copolymer is a valuable cosmetic ingredient renowned for its film-forming, binding, and opacifying properties, which enhance product texture and stability without penetrating the skin.
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