Synthesis and Characterization of Several Degradable Aliphatic Polyanhydrides

The following copolymers based on aliphatic sebacic acid were synthesized through a vacuum-melt polycondensation process:poly(sebacic acid)-b-poly(isophthalic acid)(PSA-PIPH).poly (sebacic acid) -b- (tartaric acid) (PSA-PTTA). poly (sebacic acid) -b-poly (ethylene glycol)(PSA-PEG). copolymers of PSA and copolyether (M1= 1500) of epoxy ethane and (tetrahydrofuran)(PSA-PEG/THF). All these copolymers were characterized by means of 1H or 13C NMR. IR spectrometry. differential scanning calorimetry (DSC). Intrinsic viscosity and melting points were measured to estimate the molecular weights of polymers. DSC measurements indicated that PSA-PEG. PSA-PEG/THF have much lower crystallinity. On the other hand,PSA-PIPH and PSA-PTTA exhibit better film or fibre-forming properties than PSA.

EFFECT OF SUBSTITUTION POSITION OF HYDROXY GROUP AT BENZOIC ACID ON THE LUMINESCENT AND DEGRADATION PROPERTIES OF POLY[DI(CARBOXYPHENYL) SUCCINATE-co-SEBACIC ANHYDRIDE]S

In this work, two new diacids, di（m-carboxyphenyl） succinate （m-dCPS） and di（o-carboxyphenyl） succinate （o- dCPS）, were synthesized by reaction of m-, o-hydroxy benzoic acid with succinic chloride, respectively. Their corresponding copolymers with sebacic acid （SA）, P（m-dCPS：SA） and P（o-dCPS：SA）, were prepared by melt copolycondensation and characterized by NMR, UV and DSC methods. Compared with inherently fluorescent poly[di（p-carboxyphenyl） succinate- co-sebacic anhydride] （P（p-dCPS：SA））, P（m-dCPS：SA） and P（o-dCPS：SA） displayed different luminescent properties. P（m- dCPS：SA） could emit fluorescence under the excitation of both visible and UV light, while P（o-dCPS：SA） could only emit fluorescence when excited with UV light. Degradation rate of the two new copolyanhydrides increased with the increase of SA fraction in the copolymers. In addition, P（o-dCPS：SA） degraded more rapidly than P（m-dCPS：SA） with the same composition. Typical surface-degradation characteristics of these copolyanhydrides were observed.

The Degradation Rate of Polyanhydride (Poly(sebacic acid), diacetoxy terminated, PSADT)

The in vitro degradation rate of polyanhydride （poly（sebacic acid）, diacetoxy terminated）, also known as PSADT, was investigated. PSADT tablets with a circular cross-section were formed using a compression molding device, and then immersed into phosphate buffer saline （PBS） for in vitro degradation experiments. The mechanisms of degradation and the degradation rate were characterized by the change in molecular weight and reduction in specimen mass. In addition, the effects of processing temperature and the geometry of the formed PSADT tablets on the rate of degradation were studied. The surface morphology at different degradation times was observed by scanning electron microscopy （SEM）. The experimental results showed that PSADT exhibited sur^hce erosion due to the fact that near zero-order degradation kinetics was observed during its degradation process. Moreover, it is found that the geometry of tablets played an important role on the rate of degradation, while the processing temperature had no significant effect on the PSADT degradation rate.