mPEG(1k)-PCL(1k)-COOH is a monofunctional block copolymer which can react with amine via activation with HATU or EDC. The polymer is made of two distinct polymers, a hydrophilic PEG block attached to a hydrophobic polycaprolactone (PCL) block, which enables micelles formation in water. It can be used for drug nanocarrier formulations to enhance stability and long blood circulation of the therapeutic agents. Reagent grade, for research purpose.