| Polylactic acid (PLA) is a biodegradable material, innocuity, no stimulation, after abandons may in the nature the final hydrolysate be CO2 and H2O——no pollution to the environment . Along with society' s flourishing more and more daily, PLA application scope to be more and more widespread. This experiment mainly is by solid -state polymerization to carry on the experiment, obtains Polylactic acid (PLA) . This experiment studied the application of Polylactic acid (PLA) in medicine slow release, and optimized the preparation conditions of Gelatin -Polylactic acid (PLA)。In the first section, we summarize the recent developments of the synthesis of polylactic acid (PLA) , PLA' s basic nature, the synthetic methods and applications in each space.In the second section, we study the conditions and end - products of the experiment in which we obtain PLA by solid-state polymerization and we obtain the conclusion solid -state polymerization is one kind of environment friendly response. We obtain the synthetic product. we narrate methods of the survey polymericular weight, emphatically narrate the measuring technique and the principle which we use in the test. With this method, we survey the synthesis the polymericular weight are 2. 27×105.In the third section, Polylactic acid (PLA) microspheres were prepared by conventional solvent evaporation method using Domperidone as the medcine, PLA as the polymer which carries medcine ,Gelatin as the modifier. The products were characterized by mean diameter , load efficiency and apsulation rate . Morphological studies revealed that nanospheres were spherical in shape with smooth surfaces. Physiochemical characteristics of the nanospheres were affected by the formulation parameters. The carboxymethylated chitosan , as secondary latex , was found to serve better than chitosan. The drug encapsulation efficiency and in vitro drug release behavior were improved by changing the drug concent ration in the internal water phase , as well as the increase in molecular weight of the hydrophilic polymers in continuous phase. The result shows that the microspheres we prepared have relatively uniform diameter and the surface of the microspheres is smooth.The chief characteristics of this thesis are as follows:1,It's found that, solid -state polymerization reaction temperature is lower than fuses the condensation the temperature, the degradation reaction and other side reactions is under the very good suppression, may enhance the product the quality; The reacting system is at the solid state, the macro - molecule entire chain is fixed in the crystallizing field, but the functional group terminal grouping, the catalyst as well as the small member and so on concentrate in the amorphous region, the density increase, may enhance the response the speed, and is advantageous to the balance to the traverse; The production craft and the equipment are simple; Does not use any solvent, displacement and so on by - product, water are extremely few, also does not have the pollution.2,It's found that,the viscosity instrumentation equipment is simple, the operation convenience, the molecular weight applicable scope is big, the experimental precision is high, and the duplication is good.3,It's found that, Physiochemical characteristics of the nanospheres were affected by the formulation parameters. The carboxymethylated chitosan , as secondary latex , was found to serve better than chitosan. The drug encapsulation efficiency and in vitro drug release behavior were improved by changing the drug concent ration in the internal water phase , as well as the increase in molecular weight of the hydrophilic polymers in continuous phase. The result shows that the microspheres we prepared have relatively uniform diameter and the surface of the microspheres is smooth. PLA is the good material which is used in preparation of medicine microballoons, the gelatin is the ideal emulsifier in medicine substained release. |
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