Poly(acrylic acid), Carbomer

Poly(acrylic acid) (PAA, Carbomer) is a synthetic high-molecular weight polymer of acrylic acid. They may be homopolymers of acrylic acid, or crosslinked with an allyl ether of pentaerythritol, allyl ether of sucrose, or allyl ether of propylene. In a water solution at neutral pH, PAA is an anionic polymer, i.e. many of the side chains of PAA will lose their protons and acquire a negative charge. This makes PAAs polyelectrolytes, with the ability to absorb and retain water and swell to many times their original volume. Dry PAAs are frequently used as gels in cosmetic and personal care products. Their role in cosmetics is to suspend solid in liquids, prevent emulsions from separating and control the consistency in flow of cosmetics. For many applications PAAs are used in form of alkali metal or ammonium salts, e.g. sodium polyacrylate. Polyacrylic acid and its derivatives are used in disposable diapers, ion exchange resins, adhesives and detergents. Detergents are often copolymers of acrylic acid that can be used in both zeolites and phosphates in washing powder formulations. They are also popular as thickening, dispersing, suspending, and emulsifying agents in pharmaceuticals, cosmetics, and paints. Cross-linked polyacrylic acid has also been used in the processing of household products, including floor cleaners. PAA films can be deposited on orthopaedic implants to protect them from corrosion. Crosslinked hydrogels of AA and gelatin have also been used as medical glue, which has a high bonding strength.