4arm PEG Acetic Acid

4arm PEG Acetic Acid (4-arm PEG-COOH) is a multi-armed PEG derivative with carboxylic acid groups at each end of the four arms. Four-armed polyethylene glycol is synthesized by ethoxylation of pentaerythritol, the number of ethylene oxide units in the PEG chain may not be equal for all arms.