highly significantp < 0.01
The difference was regard to be significant (*) if p < 0.05, highly significant (**) if p < 0.01 and extreme significant (***) if p < 0.001. 3 Results and discussion 3.1 The characterization of the PELG 7 -PEG 45 -PELG 7 triblock copolymer After synthesis of the PELG 7 -PEG 45 -PELG 7 triblock copolymer via ring-opening polymerization of γ-ethyl-L-glutamate- N -carboxyanhydride (ELG-NCA) initiated by NH 2 -PEG-NH 2 , the molecular weight (Mw) and the degree of polymerization (DP) of the PELG blocks were characterized by 1 H NMR and GPC.