Controllable Degradation And Drug Release Of Polymer Materials: Design, Synthesis And Properties Of Polycarbonate Anhydride

Controlled drug delivery technology represents one of the most rapidly advancing areas of science in which chemists and chemical engineers are contributing to human health care. Such delivery systems offer numerous advantages compared to conventional dosage forms including improved efficacy, reduced toxicity, and improved patient compliance and convenience. Such systems often use synthetic polymers as carriers for the drugs. The properties of polymer matrix could be modified to delivery the drug in a controlled way. The molecular design was used to develop the polymers for specialty applications. Thus, the literatures were reviewed which based on the consideration of the degradation mechanisms and the structural design of polymer. Due to the aliphatic polycarbonate and polyanhydride were biodegradable, a material which combine the well processability of aliphatic polycarbonate and the controllable degradation property of polyanhydride would be degradable too. The degradation properties of novel material, poly(carbonate anhydride), could be adjusted by modif~ying its structure. Therefore, the synthesis, degradation properties and drug release behavior of poly(carbonate anhydride) were presented for the first time in this paper. It is the first time we use a suitable way to prepare oligo(alkylene carbonate) diacid and its homopolymer. The linear oligo(alkylene carbonate) diol (OACD) was prepared by ester exchange reaction. Elemental analysis, IR and 1H NMR spectroscopy confirmed the structure and composition of OACD. DSC analyzed the thermal properties of OACD and its number average molecular weight was determined with VPO. The dicarboxylic acid derived from OACD with succinic anhydride was underwent melt polycondensation via its mixed anhydride with acetatic acid to obtain poly(alkylene carbonate anhydride)(PACA). DSC analysis showed PACA had low Tg (< -30C). The structure of PACA was characterized by [R and 1H NMR spectroscopy. In vitro degradation tests indicated that the degradation rate of poly(alkylene carbonate) was improved greatly with the incorporation of anhydzide groups. The degradation rate of PACA was higher than that of polyQrimethylene carbonate). Over a 30-week period, the number average 4 molecular weight (Mn) of PTMC decreased 7%, while that of PACA decreased 36-58% after 15 days in vitro degradation. It was found that the degradation rate depended on the content of anhydride bonds of PACA. Owing to the anhydride bonds in PTMCSA2000 were more than that of PTMCSA 1000, the (Mn0-Mn)/Mn of PTMCSA2000 and PTMCSA1000 after 15 days in vitro degradation was 57.8% and 44.7% respectively. The (Mn -Mn)/Mn of PTMCSA2000 and PHMCSAI200 after 15 days in vitro degradation was 5 7.8% and 44.7% respectively, which suggested that the degradation rate of PACA depended on its hydrophobicity too. The number of methylene groups of PHIMCSAI200 and PTMCSA2000 was 364 and 241 respectively, indicated that PI-LMCSA was more hydrophobic than PTMCSA. The carbonate segments in PACA were difficult to degrade and diffuse away and the samples did not show weight loss after three months? degradation. To further improve the degradation rate of poly(alkylene carbonate anhydride), more labile bonds should be introduced into the polymer backbone. Thus, the dicarboxylic acid derived from OACD was underwent melt copolycondensation with sebacic acid via their corresponding mixed anhydrides with acetatic acid and obtained a...