聚乳酸乙醇酸的固相聚合研究

Study on the Synthesis of Copoly(lactic acid-co-glycolic acid)by Solid-state Polymerization

为了制备安全、经济且能满足生物医学工程材料要求的聚乳酸乙醇酸(PLGA),以乙醇酸(GA)和外消旋乳酸(LA)为原料,在无催化剂条件下熔融聚合制备低聚物,而后引入固相聚合合成PLGA.采用红外光谱、黏度法、X射线衍射、差示扫描量热对产物进行表征,探讨了固相聚合条件对PLGA结构的影响.结果表明,固相聚合明显提高了聚合物的分子质量,分段控温聚合更有利于聚合物分子质量的提高,可使PLGA的分子质量提高到固相聚合反应前的2.46倍.低聚物在压力0.001MPa条件下,先后经过135℃/4h,160℃/8h,165℃/20h固相聚合后,其分子质量可达到9.34×104 u.在一定时间内,随着反应的进行,聚合物的分子质量不断提高,其熔点也随着固相时间的延长而增大.

The object of this study is to synthesize poly（lactic acid-co-glycolic acid） （PLGA） which is safe,economical and can meet the requirements of biomedical engineering material. Starting from a mixture of glycolic acid （GA） and lactic acid（LA）, PLGA was synthesized through direct melt polycondensation without catalysts,the condition of solid-state polymerization were especially stud- ied. The products were characterized by FTIR,Ubbelohde viscosity method, X-ray diffraction （XRD） and differential scanning calo- rimetry （DSC）. Effects of the conditions of solid-state polymerization on structure of product were discussed. The results showed that the viscosity-average molecular weight（M） of PLGA was significantly improved, and the M of PLGA with different temperature controlling was much higher,the result demonstrated that the M~ of PLGA could be 2.46 times as large as that of PLGA without the solid-sate polycondensation. When PLGA was synthesized at the reaction for 4 h at 135 ℃ ,8 h at 160 ℃ ,finally 20 h at 165 ℃ ,the M of PLGA could reach to 9.34×10^4u. In a certain period of time, the M and melting point of PLGA increased as the reaction time increased.