Sodium Polyacrylate (PAAS)

Sodium Polyacrylate (PAAS) – Superabsorbent Polymer for Hygiene, Cosmetics, and Agriculture

Chemical Structure and Synthesis
Sodium polyacrylate is a high‑molecular‑weight polymer produced by free‑radical polymerization of acrylic acid, followed by neutralization with sodium hydroxide. Its repeating unit can be represented as:
[–CH₂–CH(COONa)–]ₙ
The polymer contains numerous ionic carboxylate groups (–COONa), which confer high hydrophilicity and the ability to absorb and retain large volumes of water. The degree of crosslinking can be adjusted to control swelling capacity, gel strength, and absorption rate.

Physicochemical Properties

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

• Gel formation: Upon contact with water, forms a three‑dimensional hydrogel with rapid swelling.

• Ionic nature: The presence of carboxylate groups ensures strong affinity for water and electrolyte solutions.

• Porosity: The swollen gel has a porous structure that facilitates water uptake and release.

• Thermal stability: Stable under normal processing and storage conditions.

• Biocompatible: Non‑toxic and safe for contact with skin and biological tissues.

Applications

• Hygiene products: Diapers, adult incontinence products, sanitary napkins – provides excellent absorbency and leakage protection.

• Cosmetics: Gels, creams, lotions, serums – acts as a thickener, stabilizer, and water‑binding agent; improves texture and moisturization.

• Agriculture: Soil moisture retention (water‑saving agriculture), hydrogel for plant growth, and water‑holding agents for drought conditions.

• Food: Used as a thickener and stabilizer in certain food products (subject to local regulations).

• Other: Used in industrial water treatment, as a dust suppressant, and in various absorbent applications.

Key Benefits

• Exceptional water absorption and retention capacity.

• Forms clear, stable hydrogels with high viscosity.

• Improves skin feel and moisturization in cosmetic formulations.

• Enhances absorbency and leakage protection in hygiene products.

• Reduces water consumption in agriculture and improves crop yield.

• Safe, non‑toxic, and environmentally compatible.

• Available in various grades (crosslinked, linear, with different particle sizes) for tailored performance.

Recommended Use
Typical usage levels vary widely depending on the application:

• Hygiene products: 10–30% of the absorbent core.

• Cosmetics: 0.1–5.0% for thickening and gel formation.

• Agriculture: 0.1–1.0 kg per square meter for soil amendment.

• For optimal performance, disperse in water with agitation; crosslinked grades may require specific hydration conditions.

Safety and Handling

• Generally recognized as safe for use in hygiene, cosmetic, and agricultural applications 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.