mPEG(1k)-PLGA(5k)-COOH is a micelle-forming polymer for drug encapsulation in drug delivery system. The copolymer contains two different hydrophobicity polymers, poly(lactide-co-glycolide) (PLGA) as a hydrophobic block and PEG as a hydrophilic block. The polymer has terminal carboxyl tethered to PLGA which can react with amine molecule to form a stable amide linkage in presence of activator, such as HATU or EDC. The polyester PLGA is biodegradable via hydrolysis on the ester bonds. Reagent grade, for research purpose.