Polyglyceryl-4 Isostearate (Mono)

Polyglyceryl-4 Isostearate – Balanced Non-Ionic Emulsifier for Stable Cosmetic and Pharmaceutical Emulsions

Basic Information

• INCI Name: Polyglyceryl-4 Isostearate (Mono)

• CAS Number: 91824-88-5 (common for polyglyceryl isostearates; specific grade may vary)

• Synonyms: Tetraglyceryl monoisostearate, Polyglycerol-4 monoisostearate, PG-4 Isostearate

• Appearance: Pale yellow to amber viscous liquid or waxy solid

• HLB Value: Low to medium (suitable for W/O and O/W emulsions)

• Solubility: Soluble in oils and organic solvents; dispersible in water

• Storage: Store in tightly sealed containers in a cool, dry place, protected from light and moisture

Chemical Structure and Synthesis
Polyglyceryl-4 isostearate is a non-ionic monoester produced by the selective esterification of polyglycerin-4 (tetraglycerin) with one molecule of isostearic acid. The synthesis can be represented as follows:
PG₄ + Isostearic Acid → Polyglyceryl-4 Isostearate + H₂O
where PG₄ denotes polyglycerin-4. The retention of multiple free hydroxyl groups from the four glycerol units provides water solubility, while the isostearyl chain offers lipophilicity, creating a balanced amphiphilic structure that effectively reduces interfacial tension and stabilizes both water-in-oil (W/O) and oil-in-water (O/W) emulsions.

Physicochemical Properties

• Balanced hydrophilicity-lipophilicity: The four glycerol units provide excellent water compatibility, while the isostearyl chain enhances oil solubility, enabling uniform distribution in complex emulsion systems.

• Effective emulsifying activity: Significantly reduces interfacial tension, ensuring stable and homogeneous emulsions with a smooth, non-greasy feel.

• Broad compatibility: Non-ionic nature ensures compatibility with a wide range of ingredients, surfactants, and pH levels.

• Thermal and chemical stability: Resistant to hydrolysis and oxidation under normal processing and storage conditions.

• Good skin compatibility: Mild and non-irritating, suitable for sensitive skin and baby care products.

• Biodegradable and derived from renewable plant-based sources.

Applications

• Cosmetics and personal care: Used as a primary or co-emulsifier, thickener, and stabilizer in W/O and O/W creams, lotions, serums, sunscreens, makeup removers, lip cosmetics, and hair care products. Provides stable, elegant textures with good spreadability, moisturizing properties, and emollient benefits.

• Pharmaceuticals: Employed as an emulsifier, solubilizer, and penetration enhancer in topical ointments, creams, and suppositories for uniform distribution of active ingredients.

• Industrial: Applied as a dispersant, lubricant, and stabilizer in specialty chemical formulations.

Key Benefits

• Effective emulsification for both W/O and O/W systems.

• Mild and non-irritating – suitable for sensitive skin and baby products.

• Emollient properties – softens and conditions skin and hair.

• Excellent spreading and moisturization.

• Thermal and chemical stability – reliable performance over time.

• Biocompatible, biodegradable, and of natural origin.

• Compatible with a wide range of cosmetic, pharmaceutical, and industrial ingredients.

• Acts as a co-emulsifier, thickener, and stabilizer in complex formulations.

Recommended Use
Typical usage levels range from 1–5% of the formulation, depending on the desired emulsion stability, viscosity, and texture. For optimal performance, dissolve in the oil phase at elevated temperatures (60–70°C) before emulsification. Can be combined with co-emulsifiers and thickeners for tailored rheology.

Safety and Handling

• Generally recognized as safe for use in cosmetics and personal care at recommended concentrations.

• Low irritation potential; well-tolerated by skin and mucous membranes.

• Avoid contact with strong oxidizers and acids.

• Store in a cool, dry place, away from direct sunlight.

• Use appropriate personal protective equipment (gloves, safety goggles) when handling.

Quality Assurance
Each batch is tested for acid value, saponification value, and emulsification performance to ensure consistent quality.