PCL(1k)-PEG(5k)-VS contains two distinct polymers, a hydrophobic polycaprolactone (PCL) block and a hydrophilic PEG block, with terminal viniyl moiety for reaction with thiol. The polymer can form micelles in water with PCL core and PEG shell formation. The core can be used to entrap hydrophobic drugs for controlled release drug delivery. Reagent grade, for research purpose.