Methyl-PEG15-acid (methyl-polyethylene glycol 15-acid, CAS: 2933174-52-6) is a linear polyethylene glycol derivative. Its structure consists of 15 ethylene glycol units (PEG15) terminated with a single methoxy group and an end carboxylic acid group (-COOH), with a molecular formula of C₃₄H₆₈O₁₈. The production process typically involves ethylene glycol polymerization and carboxylation reactions, achieving uniform molecular weight through precise control of reaction conditions (such as temperature and catalyst ratio). Due to its excellent biocompatibility and water solubility, this product is widely used in protein modification, construction of drug delivery systems, and bioconjugation reactions. As a linker, it enhances the solubility and stability of target molecules while reducing immunogenicity, making it a key intermediate in the biopharmaceutical field.