PCL(4k)-PEG(5k)-N3 is an azido amphiphilic block copolymer which is reactive with cyclooctyne (DBCO/BCN) via SPAAC or with terminal alkyne via CuAAC. In water, the polymer can form micelles where the core and shell are made of hydrophobic polycaprolactone (PCL) and hydrophilic PEG, respectively. It can be used to prepare drug nanocarrier in drug delivery system. Reagent grade, for research purpose.