Poly (acrylic acid), also known as PAA, is a derivative of acrylic acid which when in a water solution at neutral pH is an anionic polymer. Partially or wholly deprotonated PAAs are polyelectrolytes, with the ability to absorb and hold water while expanding to numerous times their original volume. These properties make polyacrylic acid the base for numerous applications.

Uses

Poly (acrylic acid) is used in applications requiring strong carboxylic content without an appreciable increase in viscosity. Application areas include paper sizing, drilling fluids, and water treatment.

Polyacrylic acid can be neutralized with a variety of reactants including ammonium hydroxide, selected amines, urea, and caustic. Neutralized derivatives have been used in a variety of applications, including hand creams, toothpaste, shaving creams, latex thickeners, and hand cleaners. About 25% of polyacrylic acid is used for detergents and dispersants.

Polyacrylic acid is considered to be a first mucoadhesive polymer and the protonated form at an acidic pH is responsible for mucoadhesion. It is used as artificial tears to treat dry eye syndrome. Polyacrylic acid forms the hydrogen bond between its –COOH groups and sialic –COOH groups of the mucin glycoprotein.

Synthesis

Poly (acrylic acid) is synthesized in water-borne system via radical polymerization reaction using potassium persulfate and sodium pyrosulfate as initiator and iron (II) sulfate pentahydrate as chain length regulator.

Solubility

Poly (acrylic acid) is soluble in water, alkali water, alcohols, formamide, and dimethylformamide. 1,4-Dioxane and 0.2 M aqueous HCl were reported as theta solvents of Poly (acrylic acid) in which polymer chains behave as ideal chains.