Abstract
Crystalline polymers of polyanhydrides in the past were applied in textile industry, however, the application was limited due to their property of water sensitivity at room temperature. In 1980s, polyanhydrides were used for drug delivery system with broad potential usage. These materials, as well as their degradation products, are not only degradable but also highly biocompatible as has been demonstrated by tissue response and toxicological study. In the preliminary study, poly(sebacic anhydride) was synthesized via melt-condensation. In addition, poly(ethylene glycol) was introduced into poly(sebacic anhydride) system via melt condensation process for the purpose to adjust the hydrophilicity to induce the applications of polyanhydride system. Crystallinity, phase behavior, and visco-behavior of these synthesized poly(sebacic anhydride-co-ethylene glycol) were investigated and discussed. These results may provide information for further studies or applications. Storage stability of synthesized materials was studied using gel permeation chromatography and differential scanning calorimeter to analyze their depolymerization behavior. Erosion and degradation behaviors of copolymers in buffers were observed by scanning electron microscope and examined by weight residual analysis. It was found that surface erosion behavior was replaced by surface-layer erosion with poly(ethylene glycol) introduced into polyanhydride system, however, stable degradation rate of polymeric matrix was still kept. These synthesized copolymers were also tested for encapsulation of modeling drugs, p-nitroaniline (hydrophobic) and Brilliant Blue G (hydrophilic). Phase behavior and polymer-drug interaction was studied, and discussed with drug releasing behavior in neutral and acidic buffers at pH 7.4 and 4.0.