Science
Mechanism of Action
Polystyrene/Hydrogenated Polyisopentene Copolymer primarily functions through its polymeric structure, forming a flexible film on the skin to provide water-resistant and long-wear properties by enhancing product adhesion. Within a formulation, it acts as a light stabilizer, protecting sensitive components from degradation. It also serves as a viscosity-increasing agent, an opacifying agent, a surfactant, and a suspending agent, contributing to uniform ingredient dispersion and the stabilization of water-in-oil emulsions.
Research
Clinical Evidence
Low confidenceN/A
Transparency
Dusting Analysis
The Formula
Formulation
Stability
As a high molecular weight, inert polymer, this ingredient significantly contributes to product texture and effectively stabilizes water-in-oil (W/O) emulsions. While not truly soluble in the strictest sense, it can swell within certain organic solvents. Its stability is broad, with no specific optimal pH range for formulation having been identified as critical.
Safety
Safety Profile
The Cosmetic Ingredient Review (CIR) Expert Panel has concluded that Polystyrene/Hydrogenated Polyisopentene Copolymer is safe for use in cosmetic products under current applications and concentrations. This assessment is based on its large molecular size, which makes percutaneous absorption unlikely, and negative findings from toxicity tests. Any detectable residual styrene or 1,3-butadiene monomers in cosmetic formulations are considered to be substantially below levels of concern.
Your Skin
Skin Compatibility
Our Assessment
Verdict
This copolymer is a valuable formulation enhancer, providing essential film-forming, water-resisting, and texture-improving benefits across a wide array of cosmetic applications, all supported by a robust safety profile.
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References
Sources