Synthesis, characterization, and degradation behaviors of poly(D,L-lactide-co-glycolide) modified by maleic anhydride and ethanediamine

In order to improve hydrophilicity and settle the acidity in hydrolysis, a novel ethanediamine (EDA) and maleic anhydride (MAH) modified poly(D,L-lactide-co-glycolide) (PLGA) polymer (EMPLGA) was synthesized. Fourier Transform Infrared Spectrometer (FTIR), Gel Permeation Chromatography (GPC), Nuclear Magnetic Resonance (1HNMR), titration and the water contact angles were employed to characterize the synthesized polymer. The effects of various polymerization conditions on weight average molecular mass (Mw), polydispersity index (PDI) and anhydride content of MPLGA were investigated. The degradation behaviors of PLGA, MPLA and EMPLGA were also studied by observation of the changes of the pH value of incubation medium, molecular weight and weight loss ratio for a time interval of 25 days in-vitro, respectively. The results showed that MPLGA with high anhydride content was successfully obtained by directly ring-opening polymerization and ethanediamine was further grafted onto MPLGA, and there is almost unchanged in Mw between MPLGA and EMPLGA polymers. The introduction of anhydride and amino groups improved the hydrophilicity of PLGA. A uniform degradation of EMPLGA was observed in comparison with an acidity-induced auto-accelerating degradation featured by PLGA and MPLGA. The results revealed that the introduction of ethanediamine into PLGA has weakened or neutralized the acidity of PLGA degradation products.