PCL(2k)-PEG(1k)-N3 is a self-assembling block copolymer with polycaprolactone (PCL) as hydrophobic segment and PEG as hydrophilic block. The azide is reactive with cylooctyne via SPAAC or with terminal alkyne via CuAAC. The polymer can be used to prepare nanoparticles for drug delivery. Reagent grade, for research purpose.