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Moumoujus

BETA-SITOSTERYL (OCTADECENE/MA) COPOLYMER.

Valuable CAS 1013637-82-5 / FILM FORMING

A high-performance lipophilic copolymer that blends the structural resilience of a synthetic film-former with the biological affinity of plant-derived phytosterols. It creates a flexible, breathable shield on the skin's surface to prevent moisture loss while providing a sophisticated, soft-focus finish.

Summary

film forming emollient barrier repair photostabilizer

Science

Mechanism of Action

This copolymer utilizes an octadecene/maleic anhydride framework to establish a structured film that reinforces the stratum corneum. By integrating beta-sitosterol—a lipid that mimics the skin's natural sebum—it simultaneously replenishes the skin barrier and smooths texture irregularities through a 'poly-filling' effect.

Research

Clinical Evidence

High confidence
Effective range 0.5–5%
Optimal

2%

Key findings

  1. 01 Demonstrated to significantly enhance the photostability of UVA filters like Avobenzone and boost water resistance in sunscreen systems.
  2. 02 Shown to function as a high-performance barrier agent that reduces Transepidermal Water Loss (TEWL) and improves the longevity and gloss of topical applications.

Transparency

Dusting Analysis

Not commonly dusted
Min. effective
0.5%
Red flag below
0.2%

With functional benefits appearing at concentrations as low as 0.5%, it is rarely 'dusted' in the industry; however, therapeutic barrier repair usually requires levels closer to 2%.

The Formula

Formulation

Solubility
Oil
Optimal pH 4 – 8
0 7 14

Stability

Highly resistant to oxidation; requires heating to 70-80°C for proper phase integration. Excellent stability in anhydrous (water-free) formulas.

Synergies

  • Avobenzone
  • Lipophilic sun filters
  • Emollients
  • Ceramides

Conflicts

  • Highly polar aqueous systems
  • Strong oxidizing agents

Safety

Safety Profile

CIR Status
Safe as used
Max tested
5%
Pregnancy
Safe
Sensitization risk Low

The base polymer and its esterified derivatives are well-tolerated and specifically optimized for leave-on products, including sensitive lip and eye areas.

Your Skin

Skin Compatibility

Yes Normal
Yes Dry
Yes Oily
Yes Sensitive
Irritancy Low
Comedogenicity Low

Our Assessment

Verdict

Valuable

An exceptional multi-functional ingredient that bridges the gap between mechanical barrier protection and biological lipid replenishment.

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