Sodium Polyacrylate CAS 9003-44-7

Sodium Polyacrylate – High-Molecular-Weight Superabsorbent Polymer for Cosmetics and Hygiene Products

Basic Information

• CAS Number: 9003-44-7

• Molecular Formula: [–CH₂–CH(COONa)–]ₙ

• Appearance: White powder or granules

• Solubility: Highly hydrophilic; forms viscous solutions even at low concentrations

• Storage: Store in a cool, dry place, protected from moisture and direct sunlight

Overview
Sodium polyacrylate is a high-molecular-weight polymer produced by free-radical polymerization of acrylic acid, followed by neutralization with sodium hydroxide. Its structure consists of a long carbon backbone with numerous sodium carboxylate groups (–COONa), making it highly hydrophilic and capable of absorbing and retaining large amounts of water. This polymer is widely used as a thickener, dispersant, stabilizer, and superabsorbent in cosmetic, personal care, and hygiene products.

Mechanism of Action
Upon contact with water, sodium polyacrylate swells significantly, forming a three-dimensional hydrogel network. This network traps water molecules, increasing the viscosity of the solution and providing excellent water retention. The high molecular weight and ionic nature of the polymer contribute to its strong thickening and stabilizing effects even at low concentrations.

Key Properties

• Superabsorbent: Can absorb and retain water up to several hundred times its own weight.

• Thickening: Provides significant viscosity increase even at low concentrations.

• Stabilizing: Prevents phase separation and improves emulsion stability.

• Water retention: Keeps skin hydrated and improves product moisturization.

• Compatibility: Compatible with most cosmetic ingredients, including surfactants, oils, and active compounds.

• Non-irritating: Safe and gentle for skin contact; widely used in baby care products.

Applications

• Cosmetics and personal care: Gels, lotions, creams, serums, and sunscreens – provides thickening, stabilization, and moisturization; improves texture and spreadability.

• Hygiene products: Diapers, adult incontinence products, sanitary napkins – acts as a superabsorbent for fluid retention.

• Hair care: Styling gels and conditioners – enhances viscosity and water retention.

• Household products: Used in cleaning and water-absorbing formulations.

• Agriculture: As a soil water-retention agent (in some applications).

Key Benefits

• Exceptional water absorption and retention capacity.

• Provides effective thickening and stabilization at low concentrations.

• Improves product texture and skin feel.

• Safe, non-irritating, and suitable for sensitive skin.

• Compatible with a wide range of cosmetic and hygiene ingredients.

• Available in various molecular weights and crosslinking degrees for tailored performance.

Recommended Use
Typical usage levels range from 0.1–5.0% of the formulation, depending on the desired viscosity, water retention, and stability. For optimal performance, disperse in water with moderate agitation; crosslinked grades may require specific hydration conditions.

Safety and Handling

• Generally recognized as safe for use in cosmetics and hygiene products at recommended concentrations.

• Low irritation potential; well-tolerated by skin.

• Avoid inhalation of dust – use appropriate personal protective equipment (gloves, dust mask, safety goggles).

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

• Shelf life: typically 24 months under recommended storage conditions.

Quality Assurance
Each batch is tested for absorption capacity, viscosity, and residual monomer content to ensure consistent performance.