PCL(4k)-PEG(5k)-MAL is a block copolymer containing polycaprolactone (PCL) (hydrophobic) and PEG (hydrophilic). Upon dispersion in water, the polymer self-assembles to form micelles with PCL core and PEG shell. The core can be used as reservoir for hydrophobic drugs while the shell can provide protection from degradation (enzymatic/hydrolysis). The terminal maleimide is reactive with thiol (SH) at physiological pH 6.5-7.5 via thioether bond formation. Reagent grade, for research purpose.