PCL(1k)-PEG(2k)-NH2 is a biodegradable block copolymer with polycaprolactone (PCL) hydrophobic block tethered to a PEG hydrophilic block. The polymer is reactive with NHS ester or with carboxylic acid in the presence of activator, such as HATU/EDC. It can also self-assemble in water to form micelles which can be used to formulate controlled realease drug delivery system. Reagent grade, for research purpose.