Poly(fumaric-co-sebacic anhydride) - A degradation study as evaluated by FTIR, DSC, GPC and X-ray diffraction

The degradation of three poly(fumaric-co-sebacic anhydride) [P(FA:SA)] copo lymers is examined in a composition of microspheres made by the hot melt en capsulation process. The emergence of low molecular weight oligomers occurs during degradation of the copolymer microspheres, as evidenced by a variet y of characterization methods. Characterization was conducted to determine the extent of degradation of the polyanhydride microspheres using Fourier-t ransform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and X-ray diffraction. It is demon strated that degradation of P(FA:SA) is greatly accelerated at basic pH, ye t there is little difference between degradation in neutral and acidic buff ers. A good correlation exists between the results of each characterization method, which allows a better understanding of the degradation process and the resulting formation of low molecular weight oligomers in poly(fumaric- co-sebacic anhydride). (C) 1999 Elsevier Science B.V. All rights reserved.