Willow active extract of the bark, called salicin, was isolated to its crystalline form in 1828 by Henri Leroux, a French pharmacist, and Raffaele Piria, an Italian chemist, who then succeeded in separating out the compound in its pure state. In 1897, Felix Hoffmann created a synthetically altered version of salicin (in his case derived from the "Spiraea" plant), which caused less digestive upset than pure salicylic acid. The new drug, formally acetylsalicylic acid, was named Aspirin by Hoffmann's employer Bayer AG. This gave rise to the hugely important class of drugs known as nonsteroidal anti-inflammatory drugs (NSAIDs). Some of humans'
Polyacrylic acid of PAA have been prepared that are responsive to pH and temperature stimuli, demonstrating the possibility to be used for drug delivery purposes. ATRP has been used to growth PAA brushes from the surface. One reported approach was with surface-initiated ATRP of tert-butyl acrylate that was subsequently deprotected through pyrolysis to form the carboxylic acid. These PAA brushes can form chelate complex with silver and can therefore exhibit antibacterial activity. Polyacrylic acid Poly(acrylic acid) (PAA; trade name Carbomer) is a synthetic high-molecular weight polymers of acrylic acid. The IUPAC name is poly(1-carboxyethylene. They may be homopolymers of acrylic acid, or