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Moumoujus

SILICONE QUATERNIUM-21.

Insufficient Data CAS - / SKIN CONDITIONING - EMOLLIENT, SURFACTANT - EMULSIFYING

Silicone Quaternium-21 is a silicone-based conditioning agent engineered to form a breathable film on the skin's surface. This barrier effectively minimizes transepidermal water loss, promoting sustained hydration and a noticeably smoother, softer complexion. It also offers cosmetic benefits such as enhanced product spreadability and a luxurious skin feel.

Summary

Emollient Emulsifying Conditioning Barrier Support Moisturizing

Science

Mechanism of Action

As a silicone-based quaternary ammonium compound, Silicone Quaternium-21 functions primarily as a conditioning agent and film-former. It establishes a breathable, protective barrier on the stratum corneum, which actively prevents moisture evaporation while allowing normal skin respiration. This sustained moisture retention contributes to skin hydration, softness, and smoothness. Beyond its hydrating properties, general silicones can impart a 'soft focus' effect by scattering light, potentially minimizing the appearance of fine lines, and may support the reduction of keloid and hypertrophic scar formation. Its inclusion in formulations also contributes to improved texture and spreadability.

Research

Clinical Evidence

Low confidence
Effective range N/A
Optimal

1%

Key findings

  1. 01 A related silicone quaternary microemulsion, when incorporated at 1% in shampoo formulations, demonstrated superior conditioning performance, evidenced by enhanced smoothness and softness.

Transparency

Dusting Analysis

Not commonly dusted

The Formula

Formulation

Solubility
Both
Optimal pH N/A
0 7 14

Stability

Specific optimal pH for Silicone Quaternium-21 is not documented; however, related Silicone Quaternium-8 is stable within a pH range of 5-7, and acceptable pH values for a silicone quaternary microemulsion in shampoos were between 6.59 and 7.17.

Conflicts

  • strong concentrated acids
  • strong concentrated bases
  • hydrofluoric acid
  • acetone
  • small non-polar molecules (e.g., fuels, paint thinners)

Safety

Safety Profile

CIR Status
Not reviewed
Sensitization risk Low

While no specific Cosmetic Ingredient Review (CIR) report exists for Silicone Quaternium-21, the CIR Expert Panel has affirmed the safety of various other dimethicone crosspolymers and Polyquaternium-11. General silicones are broadly regarded as safe in cosmetic applications, demonstrating low irritation potential and typically non-sensitizing properties.

Your Skin

Skin Compatibility

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

Our Assessment

Verdict

Insufficient Data

Silicone Quaternium-21 offers compelling conditioning and barrier-forming benefits across all skin types; however, a definitive verdict awaits specific CIR review, direct clinical efficacy data, and irritancy/comedogenicity assessment for this precise ingredient.

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References

Sources