PCL(5k)-PEG(5k)-COOH is an amphiphile polymer with hydrophobic polycaprolactone (PCL) and hydrophilic PEG. The self-assembling polymer forms micelles which can be used to entrap hydrophobic drugs. The terminal carboxyl can react with amine in the presence of HATU or EDC to form a stable amide bond. Reagent grade, for research purpose.