| Poly(lactic acid) (PLA) is a heeded material in the field of biodegradation and medicinal material because it has better biocompatibility and biodegradability and degradation product can participate in body metabolism.Particle diameter and its distributing of polymer microsphere will have more effect on medicating manner and curative effect, whether as targeted drugs or as slow-release/control release medicinal carrier. As the carrier of targeted drugs, different particle diameter distributing of polymer microsphere will lead to different target. When prepared, it is very important to control particle diameter distributing of microsphere. In the thesis, PLA microsphere and its composite microsphere were prepared and their morphologies have been always investigated.There are many methods on PLA microsphere prepareration, for example. emulsification-solvent volatilization method, spray desiccation method, phase separation method and so on. In this thesis, poly(N-isopropylacrylamide) (PNIPAm) was synthesized by atom transfer radical polymerization (ATRP) method (its lower critical solution temperature is 20.9℃), PLLA microsphere and 80PLA/20PNIPAm (w/w) composite microsphere were always prepared by emulsification-solvent volatilization method, the effects of temperature and stirring speed on microsphere's particle diameter had been studied. By experimenting, the optimal preparation condition had been determined, more homogeneous particle diameter and narrow distributing microsphere had been prepared. PLLA/PNIPAm composite microsphere had been prepared. Infrared spectrum result shows that two components of composite microsphere are PLA and PNIPAm, respectively. TEM result shows that the composite microsphere is core-shell structure. Growth mechanism of this novel core-shell microsphere had been investigated. It will provide dependable foundation for further research of PLA carried drug microsphere.
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