PCL(10k)-PEG(3k)-N3 is a monofunctional block copolymer which can self-assemble to form micelles in aqueous media. The amphiphilic polymer is functionalized with azide moiety which is reactive with a terminal alkyne in the presence of Cu catalyst or with a cyclooctyne, such as DBCO or BCN, without the need of Cu catalyst. The polymer is commonly used to prepare nanoparticles in nanomedicine to achieve long blood circulation and targeted delivery. Reagent grade, for research purpose.