PEG-PLA block copolymers were synthesized by anionic ring-opening polymerization at room temperature under argon atmosphere [11]. Typical procedures are as follows: 0.5 mmol potassium naphthalene (1.8 ml) was added to 20 ml of dry THF including 0.5 mmol (4 ml) of 2-methoxyethanol. After a few minutes of stirring, 60 mmol (3 ml) of condensed EO was added via a cooled syringe to the formed solution of potassium 2-methoxyethoxide. The polymerization of EO proceeded for 2 days, resulting in a highly viscous solution. After sampling a small portion of the solution via syringe for GPC analysis, 20.8 mmol (25 ml) of an LA solution in THF (8.3 mol/l) was introduced, and the polymerization proceeded for 4 h. The polymer was precipitated into a 30-fold excess of ice-cold 2-propanol and centrifuged for 30 min at 3500 rpm. The polymer was then freeze-dried in benzene to form a white powder with a yield of ∼80%. The obtained sample was stored at −20°C until use.