PCL(1k)-PEG(3k)-VS is widely used amphiphilic polymer to prepare drug loaded nanoparticles for drug delivery or scaffold in tissue engineering. It is an amphiphilic block polymer with a PEG hydrophilic attached to a hydrophobic polycaprolactone (PCL) block. The alkene from vinylsulfone is reactive with thiol in the presence of photoinitator. Reagent grade, for research purpose.