PCL(2k)-PEG(2k)-MAL is a self-assembling block copolymer with polycaprolactone (PCL) as hydrophobic segment and PEG as hydrophilic block. The maleimide is reactive with thiol molecule to form a stable thioether linkage. The polymer can be used to prepare drug loaded nanoparticles for targeted delivery. Reagent grade, for research purpose.