A series of poly(ethylene glycol)-block-poly(epsilon-caprolactone) diblock copolymers was synthesized and fully characterized. In particular, MALDI-TOF MS results revealed interesting new insights into their molecular architecture. Small and defined micelles could be prepared from these block copolymers. Utilizing a high-throughput screening approach, it was observed that these micelles are able to encapsulate/solubilize different guest molecules (e.g. drugs) depending on the solubility of the guest in water. Furthermore, it could be proven that a guest is located within a micelle and that these micelles can be utilized as transport vehicles for the encapsulated guest molecules.