Patent ID: 8853351

Claim:
A method for preparing an amphiphilic block copolymer comprising a hydrophobic polymer block of a poly(α-hydroxy acid), the method comprising the steps of: dissolving an amphiphilic block copolymer comprising a hydrophobic polymer block of a poly(α-hydroxy acid) into a water-miscible organic solvent; mixing a resultant polymer solution with water or an aqueous solution containing an alkali metal salt for 10 minutes to 24 hours to hydrolyze unreacted monomers contained in the amphiphilic block copolymer, wherein the alkali metal salt is sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate or lithium carbonate; adding sodium chloride or potassium chloride to the resultant solution in order to separate the solution into an organic solvent layer and an aqueous layer via salting out; and collecting the organic solvent layer and removing the organic solvent therefrom to recover a polymer, wherein the steps are performed sequentially.