A two-step process was used to synthesize the high molecular weight poly (lactic acid) using thionyl chloride as an activator for the polycondensation of prepolymer of lactic acid. The products were characterized by G...A two-step process was used to synthesize the high molecular weight poly (lactic acid) using thionyl chloride as an activator for the polycondensation of prepolymer of lactic acid. The products were characterized by GPC, DSC, and 1H-NMR. Poly (L-lactic acid) (PLLA) with molecular weight Mw: 32875 was obtained when thionyl chloride was used, while low molecular weight PLLA Mw: 7350 was yielded without thionyl chloride. Effects of the concentration of thionyl chloride, polymerization time and bases on the molecular weight of poly (lactic acid) were investigated. In DSC scans the glass transition temperatures (Tg) of the resulting polymers varied from 25.3 to 57.6℃, and the Tg of poly(L-lactic acid) was higher than that of poly (D,L-lactic acid) (PDLLA). The melting points of poly (L-lactic acid) and poly (D, L-lactic acid) could not be found unless the polymers were obtained by thionyl chloride activator.展开更多
基金National Science Foundation of China (2977 6035)
文摘A two-step process was used to synthesize the high molecular weight poly (lactic acid) using thionyl chloride as an activator for the polycondensation of prepolymer of lactic acid. The products were characterized by GPC, DSC, and 1H-NMR. Poly (L-lactic acid) (PLLA) with molecular weight Mw: 32875 was obtained when thionyl chloride was used, while low molecular weight PLLA Mw: 7350 was yielded without thionyl chloride. Effects of the concentration of thionyl chloride, polymerization time and bases on the molecular weight of poly (lactic acid) were investigated. In DSC scans the glass transition temperatures (Tg) of the resulting polymers varied from 25.3 to 57.6℃, and the Tg of poly(L-lactic acid) was higher than that of poly (D,L-lactic acid) (PDLLA). The melting points of poly (L-lactic acid) and poly (D, L-lactic acid) could not be found unless the polymers were obtained by thionyl chloride activator.
