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Polylactide was widely used in biomedical fields due to its excellent biocompatibility and biodegradability, excellent mechanics properties and good processability. However, it does have some shortcomings such as the poor hydrophilicity and cellular affinity, and the acidity of degradation products which easy to cause inflammation, etc. in this dissertation, in order to improve the hydrophilicity and cell-substratum adhesion of the PLA material, and to endow the final material with biological function, composites of PLA with other materials (such as chitosan or cholestoerl) owning biological function were prepared. Meanwhile, the interfacial compatibility of PLA and chitosan or cholesterol was improved by introducing PLA segments into chitosan or cholesterol by chemical grafting reaction.Hydroxyethyl chitosan was synthesized by reacting 2-chloroethanol with alkalified chitosan in isopropanol. Then, hydroxyethyl chitosan-g-polylactide copolymer was synthesized by ring-opening polymerization of D,L-lactide using hydroxyethyl chitosan as macroinitiator and stannous 2-ethylhexanoate as initiator under microwave-assisted.The structure and properties of the products were characterized by FT IR, H NMR, XRD, DSC, and etc. Then a series of blend films were prepared by solution blending with polylactide, chitosan, hydroxyethyl chitosan and hydroxyethyl chitosan-g-polylactide for raw materials and using dimethyl sulfoxide as a solvent. The compatibility of blend films was characterized by SEM and DSC. The results showed that, the crystallinity of copolymer was lower than chitosan and the solubility had been improved. SEM results indicated that phase separation is obviously existent in the chitosan/polylactide blend film because of chitosan insoluble in dimethyl sulfoxide, while the compatibility of hydroxyethyl chitosan/polylactide blend film with island structure has been improved. The compatibility of hydroxyethyl chitosan-g-polylactide/polylactide blend films was very good, with the content of hydroxyethyl chitosan-g-polylactid increasing, the compatibility still maintain well.Cholesterol is a fundamental composition of mammalian membranes, with high tennodnymaic affinity for the cell membrane, universally important function in all eukaryotic cells, and homeostasis for cell survival. Therefore, a series of cholesterol-poly(L-lactide) oligomers (CHOL-PLLAn oligomers) with different molecular weight were synthesized by ring-opening polymerization of L-lactide with using cholesterol as initiator and stannous 2-ethylhexanoate as catalyst under microwave-assisted. The optimal synthesis conditions were obtained by an orthogonal experiment:irradiation time of 15 min, microwave power of 35W, temperature of 150℃and catalyst concentration of 0.10%(mol%). The products were confirmed by FT IR,1H NMR, SAXS, DSC, POM, cells experiment in vitro and etc. Results showed that the molecule of products was close to theoretical value, the structure of products was composed by cholesterol moiety and 103 helical conformation of oligo (L-lactide) chains. Product has simultaneously crystalloid and liquid crystal, which had relations to the proportion of cholesterol and PLLA molecular chain:when the content of PLLA chain was little, cholesterol was in a dominant position, and products could obviously observed liquid crystal in a lower, more wide temperature range, such as CHOL-PLLA2.5 and CHOL-PLLA5 oligimers. When the content of PLLA chain was higher, cholesterol was in a subordinate position, the crystallization capacity of PLLA was increased, products showed strong crystalline, and it could only show weak liquid crystal in a higher, narrow temperature range, such as CHOL-PLLA10 and CHOL-PLLA20 oligimers. The results of cell experiments in vitro showed that the cell adhension rate and proliferation rate of CHOL-PLLAn oligomer were obviously improved, the existence of cholesterol was better to promote 3T3 cells adhesion and proliferation.On this basis, CHOL-PLLAn oligomer/PDLLA blend films were preparaed by solvent induced phase separation, and the hydrophilicity, morphology and cellular compatibility were studied. Results show that:CHOL-PLLA2.5 oligomer could improve the hydrophilicity, while CHOL-PLLA5 oligomer could improve the hydrophobicity; small liquid crystal domain were decentralized uniformly in polylactide matrix; the introducing of cholesterol made the blend film better able to the adhesion and proliferation of 3T3 cells.
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