PCL(4k)-PEG(2k)-PCL(4k) is an amphiphile ABA triblock copolymer containing two hydrophobic polycaprolactone (PCL) blocks and a hydrophilic PEG block. The polymer is biodegradable via hydrolytic attack on the ester bonds and can be used to prepare nanoparticles/nanomicellars for targeted drug delivery. Reagent grade, for research purpose.