PCL(1k)-PEG(2k)-PCL(1k) is a linear triblock copolymer with both hydrophobic polycaprolactone (PCL) and hydrophilic PEG blocks. The amphiphilic polymer is insoluble in water but can degrade by hydrolytic attack on their ester bonds. This self-assembling polymer enables new directions for drug delivery, gene therapy, and tissue engineering. Reagent grade, for research purpose.