PCL(2k)-PEG(5k)-MAL allows self assembly when dispersed in water. The micelle structure consists of hydrophobic core (polycaprolactone (PCL)) and hydrophilic shell (PEG). It can be used to prepare drug nanocarrier in drug delivery system. The maleimide is reactive with thiol at physiological pH 6.5-7.5 to form a stable thioether linkage. Reagent grade, for research purpose.