Science
Mechanism of Action
This ingredient functions by depositing a stable, often invisible polymeric film on the skin's surface. This film serves as a physical barrier, aiding in the retention of skin moisture and offering protection from external environmental factors. Beyond its barrier properties, Polyurethane-45 contributes to improved skin texture by imparting softness and elasticity. General polyurethanes have also been observed to support wound healing processes, specifically by aiding in fibroblast organization and promoting re-epithelialization.
Research
Clinical Evidence
Low confidenceN/A
Transparency
Dusting Analysis
The Formula
Formulation
Stability
Polyurethane-45, typically provided as an aqueous dispersion, generally exhibits good stability. However, its urethane linkages are susceptible to hydrolysis, particularly in strongly acidic conditions (e.g., pH ~1-3) and highly alkaline aqueous solutions. Formulators should consider the polymer's backbone; polyether-based polyurethanes tend to show improved resistance to hydrolysis compared to polyester-based types.
Conflicts
- Strongly acidic environments (pH ~1-3) due to hydrolysis risk
- Strongly alkaline environments (high pH) due to hydrolysis risk
- Certain organic solvents (e.g., toluene, trichloroethylene, tetrahydrofuran) for general polyurethanes
- Excessive concentrations of other sensitizing ingredients (e.g., methylisothiazolinone) when combined, to prevent hazardous cumulative levels
Safety
Safety Profile
The Cosmetic Ingredient Review (CIR) Expert Panel concluded that Polyurethane-45 and related polyurethanes are safe in current cosmetic uses and concentrations, provided they are formulated to be non-sensitizing and contain no detectable residual isocyanate or other monomer precursors. These precursor diisocyanates are known occupational irritants and sensitizers, underscoring the critical importance of ingredient purity. Formulators must also consider other components in polyurethane dispersions, such as potential sensitizers like methylisothiazolinone (MI), to avoid creating formulations with hazardous cumulative sensitizer levels.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Polyurethane-45 is a valuable film-forming and moisturizing polymer suitable for all skin types, contingent on strict adherence to formulation guidelines to ensure the absence of residual monomers and safe co-ingredient levels.
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References
Sources