Stearic acid is another name for octadecanoic acid CH3(CH2)16COOH and is one of the most common fatty acids. PolyPEG-stearic acid is an amphiphilic polymer that can form micelles in aqueous solution. It has excellent hydrophobicity. This peg polymer is usually used in controlled-release drug delivery systems, which can improve drug solubility and improve drug solubility. Improve drug formulation and bioavailability.