Polyacrylic acid

Poly(acrylic acid)(PAA; trade nameCarbomer) is a synthetic high-molecular weightpolymersofacrylic acid. They may behomopolymersof acrylic acid, orcrosslinkedwith anallyletherofpentaerythritol, allyl ether ofsucrose, or allyl ether ofpropylene. In a water solution at neutralpH, PAA is ananionicpolymer, i.e. many of the side chains of PAA will lose their protons and acquire a negative charge. This makes PAAspolyelectrolytes, with the ability to absorb and retain water and swell to many times their original volume. Dry PAAs are sold as white, fluffy powders. Carbomer codes (910, 934, 940, 941, and 934P) are an indication of molecular weight and the specific components of the polymer. For many applications PAAs are used in form ofalkali metalor ammonium salts, e.g.sodium polyacrylate.

Polyacrylic acid is a weak anionic polyelectrolyte, whose degree of ionisation is dependent on solution pH. In its non-ionised form at low pHs, PAA may associate with various non-ionic polymers (such as polyethylene oxide, poly-N-vinyl pyrrolidone, polyacrylamide, and some cellulose ethers) and form hydrogen-bonded interpolymer complexes.[1]In aqueous solutions PAA can also form polycomplexes with oppositely charged polymers (for example, chitosan), surfactants, and drug molecules (for example, streptomycin).



olyacrylic acid and its derivatives are used indisposable diapers,[3]ion exchange resins, and adhesives. They are also popular asthickening,dispersing,suspending, andemulsifyingagents inpharmaceuticals,cosmetics, andpaints.[4]PAA may inactivate theantisepticchlorhexidine gluconate.[5]The neutralized polyacrylic acid gels are suitable to obtain biocompatible matrices for medical applications such as gels for skin care or skin disease treatment products. For the development of polymeric matrices which allows controlled delivery rate of active substances, the recent investigations aimed towards the clarification of the conformational changes of the polymeric gel during neutralization, light irradiation, and embedment of gold nanoparticles.