PCL(1k)-PEG(3k)-SPDP is a monofunctional amphipathic block copolymer with terminal SPDP ester which is reactive thiol (SH) via thiol exchange reaction. The copolymer consists of hydrophobic polycaprolactone (PCL) and hydrophilic PEG block which can self-assemble in water to form micelles used for sustained drug release. Reagent grade, for research purpose.