PCL(4k)-PEG(2k)-N3 is a monofunctional amphipathic polymer with hydrophobic (polycaprolactone (PCL)) block attached to hydrophilic PEG block. The polymer has terminal azide which can undergo click reaction with alkyne molecule, such as DBCO/BCN or terminal alkyne (with Cu catalyst), to form a stable triazole bond. It can be used to prepare nanoparticles for drug delivery. Reagent grade, for research purpose.