PCL(5k)-PEG(5k)-SPDP is a thiol reactive block copolymer. The polymer is amphipathic with PEG hydrophilic block and polycaprolactone (PCL) hydrophobic block. In water, the polymer can form micelles with core made of PCL and shell made of PEG. The core regions can serve as hydrophobic drugs reservoir. Reagent grade, for research purpose.