PCL(10k)-PEG(2k)-VS comprises two different hydrophilicity blocks, i.e. polycaprolactone as a hydrophobic block and PEG as a hydrophilic block. It has vinylsulfone which can react with thiol via thiol-ene reaction. The polymer can self-assemble in aqueous media and be used as strategies for sustained drug delivery using micellar nanocarriers. Reagent grade, for research purpose.