Synthesis And Character Of Star Polymer For Drug Slow Release

Star-shaped polymers were briefly reviewed and its application prospects in drug controlled released was analyzed the first part of this dissertation. New star-shaped polymers were designed and synthesized with rigid chain of PLA as its arms and epoxidized soybean oil(ESO) as its cores. The effect of ESO content on lactide ring-opening polymerization and lactic acid polycondensatin was researched. The characterization of the obtained polymers was by the means of multi-angle laser light scattering (MALLS), infrared spectrometry ( IR), nuclear magnetic resonance spectrometer (NMR), contact angle meter, differential scanning calorimeter (DSC) and classical chemical analysis to explore the structures and the properties. Thereafter, surface wettability and thermal degradation were investigated. The main work and conclusions were included as follows:(1) Crude lactide was synthesized and purified by the process of multiple distillation, then the residual lactic acid and oligomer were removed. In contrast with the conventional method of recrystallization by organic solvents, in the process of distillation, meso-lactide was obtained and the recovery rate of total lactide increased from 40% to 66%.(2) GC,1H NMR and IR analysis showed that the multiple distillation process can remove the lactic acid and impurity efficiently. The method of rapid detection meso- and D,L-lactide content was founded.(3) Synthesis star-polymers by the method of"corn-first"with lactide. The relation of ESO content on the molecular was researched. The result of GPC-MALLS and GC analysis indicted that proper ESO could accelerate the polymerization rate, increase the molecular and lactide conversation, especially the meso-lactide conversation. Base on the Sn(Oct)2 catalytic principle, the structure of the star-polymer was determined. For the ester bond is formed between the ESO and lactide, the end of the arms is hydroxy group.(4) Synthesis star-polymers by the method"arm-first"and"corn-first"with lactic acid polycondenstion, the yellow polymers were obtained. In contrast with the lactic acid direct polycondensation, the color was improved for the oxidation resistance of ESO. Synthesis obtained from former method, 13CNMR analysis detected that the linked of ESO and arms by ether bond, and the end group of arms is carboxy group. On the contrary, by the"corn-first"method, the linked of ESO and arms by ether bond by ether bond or ester bond, the end of the arms is hydroxy group or carboxy group.(5) Contact angle meter , Differential Scanning Calorimeter and Thermogravimetry analysis detected that star-polymer static water contact angle decrease , water adsorption ratio increase and the temperature of degradation decrease.The result obtained indicated that the polymerization could increase remarkably with ESO as the core, and the star-polymer has wide application prospect in the field of drug slow release.