TECHNOLOGY FOCUS - POLYMERS - Preparation (Disclosed): The preparation of the amphiphilic copolymer, comprises carrying out ring-opening polymerization of at least two N-substituted amino acid-N-carboxy anhydrides of formula (XIV) or (XV) by a liquid phase nucleophilic reaction. Preferred Components: The amphiphilic copolymer comprises: keto-amine structural units containing copolymer of formula (X1-((C(=O)-CH(R2)-N(R1))n2-(C(=O)-CH2-N(R3))m2)co-Y1) (IV); keto-amine structural units containing amphiphilic block copolymer of formula (X1-((C(=O)-CH(R2)-N(R1))n2-(C(=O)-CH2-N(R3))m2)co-Y1) (V) and (X1-((C(=O)-CH2-N(R3))n2-(C(=O)-CH(R2)-N(R1))m2)blk-Y1) (VI); keto-amine structural units containing tri-block copolymers of formula (X1-((C(=O)-CH(R2)-N(R1))n-(C(=O)-CH2-N(R3))m-(C(=O)-CH(R2)-N(R1))o)blk-Y1) (VII) and (X1-((C(=O)-CH2-N(R3))n1-(C(=O)-CH(R2)-N(R1))m1-(C(=O)-CH2-N(R3))o)blk-Y1) (VIII); tri-block copolymers of formula ((Y1-((N(R1)-CH(R2)-C(=O))n1/p-(N(R3)-CH2-C(=O))m1/p)blk-X2)p-Z) (IX) or ((Y1-((N(R3)-CH2-C(=O))n1/p-(N(R1)-CH(R2)-C(=O))m/p)blk-X2)p-Z) (X); or (star)block copolymers of formula ((Y1-((N(R1)-CH(R2)-C(=O))n/q-(N(R3)-CH2-C(=O))m/q)blk-X2-)q-Z) (XI) or ((Y1-((N(R3)-CH2-C(=O))n/q-(N(R1)-CH(R2)-C(=O))m/q)blk-X2)q-Z) (XII) or star copolymers of formula ((Y1-((N(R1)-CH(R2)-C(=O))n/q-(N(R3)-CH2-C(=O))m/q)co-X1)q-Z) (XIII).X1 = (R4O-), (R4S-), (R4ONH-), (R4NHO-), (R4NH-) or peptides;R4, R5 = alkyl or aryl;Y1 = proton, -(C(=O)-R5) (optionally substituted), -(C(=O)NH-R5), -(C(=S)NH-R5) or R5;co = copolymer;o, n2, m2 = 5-10000;blk = block copolymer;X2 = -NH-, -O-, -S-, -ONH-, -NH-O-, R4O-, R4S-, R4ONH-, R4NHO-, R4NH- or peptides;Z = alkyl (optionally branched);p = 2; andq = 3-100. EXAMPLE - N-methyl-N-carboxyglycine anhydride (203 mg) was dissolved in dry benzonitrile (2.3 ml). Then benzylamine (3.9 mu l) was added after the complete dissolution of the monomer. Then the reaction mixture was stirred at room temperature for 3.5 hours at a constant pressure of 20 mbar. Then N-propyl-N-carboxyglycine anhydride (142 mg) in benzonitrile (0.87 ml) was added and the reaction mixture was further stirred at room temperature and 20 mbar for 5 hours. Then the reaction mixture was worked upto obtain poly(N-methylglycine50-b-N-propylglycine25).