PCL(5k)-PEG(3k)-SPDP is an amphiphilic polymer which is reactive with thiol to form disulfide bond. The block copolymer contains a hydrophobic polycaprolactone (PCL) block chemically attached to a hydrophilic PEG block. Upon dispersion in water, the polymer self assembles to form micelles which can encapsulate drugs for drug delivery. Reagent grade, for research purpose.