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Moumoujus

STYRENE/ISOPRENE COPOLYMER.

Valuable CAS 25038-32-8 / FILM FORMING, OPACIFYING

Styrene/Isoprene Copolymer is a synthetic polymer primarily recognized for its film-forming properties, creating a continuous, protective layer on the skin. It also functions as an opacifying and viscosity-controlling agent, enhancing product aesthetics and stability. Its large molecular structure ensures minimal percutaneous absorption.

Summary

Film-forming agent Opacifying agent Viscosity controlling agent Emulsion stabilizer

Science

Mechanism of Action

This copolymer operates by forming a breathable, continuous film on the skin's surface, which can aid in reducing trans-epidermal water loss and offering a protective barrier. Beyond its film-forming action, it effectively reduces the transparency of formulations (opacifying) and increases their viscosity, contributing to the structural integrity and stability of water-in-oil emulsions.

Research

Clinical Evidence

Medium confidence
Effective range 0.89–4.2%
Optimal

4.2%

Transparency

Dusting Analysis

Not commonly dusted

The Formula

Formulation

Solubility
Oil
Optimal pH N/A
0 7 14

Stability

The ingredient demonstrates robust stability under typical storage conditions. It exhibits reduced swelling when exposed to alcohols compared to acrylic polymers and shows good compatibility with various active pharmaceutical ingredients in transdermal applications.

Safety

Safety Profile

CIR Status
Safe as used
Max tested
4.2%
Sensitization risk Low

The Cosmetic Ingredient Review (CIR) Expert Panel has determined Styrene/Isoprene Copolymer to be safe for its current uses in cosmetics. Due to its substantial molecular size, percutaneous absorption is not anticipated. While residual styrene monomers are a theoretical concern, any detectable levels in cosmetic products are consistently found to be well below thresholds of concern. No specific SCCS opinion or explicit FDA cosmetic status has been identified.

Your Skin

Skin Compatibility

Yes Normal
Yes Dry
Yes Oily
Yes Sensitive
Irritancy Unknown
Comedogenicity Unknown

Our Assessment

Verdict

Valuable

Styrene/Isoprene Copolymer is a valuable cosmetic ingredient, effectively providing protective film benefits, enhancing product aesthetics through opacification, and stabilizing emulsions, all supported by a favorable safety profile.

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