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ISOBUTYL POLYSILSESQUIOXANE.

Valuable CAS 221326-46-1 / NAIL CONDITIONING

Isobutyl Polysilsesquioxane is a synthetic polymer functioning primarily as a film former in precision skincare and cosmetic formulations. It creates an optically transparent, water-repellent layer on the skin, contributing to product longevity and texture.

Film former Water-repellent agent

Science

This ingredient forms a robust, three-dimensional polymeric framework upon application, creating an invisible, highly hydrophobic film on the skin's surface. This film provides a water-repellent barrier, enhancing the skin's protection against moisture loss and external elements while maintaining optical clarity.


Research

Low confidence
Effective range N/A
Optimal

N/A


Transparency

Not commonly dusted

The Formula

Solubility
Oil
Optimal pH N/A
0 7 14

Stability

Polysilsesquioxane resins containing silanols can be cured at elevated temperatures, though typical formulation and catalysis are performed at room temperature or below. Most resins tend to soften above 40 °C. Molecular silicas, particularly closed-cage structures, exhibit excellent chemical and pH stability. The slowest rate of silanol condensation, critical for polysilsesquioxane stability, is observed around pH 2, with increased rates below pH 1 and above pH 4.


Safety

CIR Status
Safe as used
Max tested
100%
Sensitization risk Low

The CIR Expert Panel has determined Isobutyl Polysilsesquioxane is safe for cosmetic use under current practices and concentrations. Although dermal irritation was tested at 100%, typical concentrations in cosmetic formulations are generally lower; related polysilsesquioxanes are reported up to 55.2% in makeup. No SCCS opinion or specific FDA pre-market approval information beyond VCRP listing is available, as is common for cosmetic ingredients.


Your Skin

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

Our Assessment

Valuable

Isobutyl Polysilsesquioxane is a valuable film-forming ingredient, creating a water-repellent and transparent layer on the skin, with a robust safety profile and low irritation risk, making it suitable for sensitive skin.


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References