Biocompatible, amphiphilic block copolymer composed of a hydrophilic PEG block and a hydrophobic PCL block. These materials have been used as a block copolymer surfactant as well as in control release and nanoparticle formulation for drug delivery applications. Well-defined materials with varying properties can be prepared by controlling the relative length of each polymer block. Hydroxyl termination allows for facile further chemical modification of these materials.