PCL(1k)-PEG(1k)-COOH is an amphiphilic block copolymer with hydrophobic block made of polycaprolactone (PCL) tethered to a hydrophilic PEG. It can self-assemble in aqueous media to form micelles and be used to prepare nanoparticles for drug encapsulation in nanomedicine/drug delivery. The acid (COOH) is reactive with amine molecule in the presence of activators, such as HATU or EDC. Reagent grade, for research purpose.