Characterization of poly(D,L-lactic acid) synthesized by direct melt polymerization and its application in Chinese traditional medicine compound prescription microspheres

摘要

From D,L-lactic acid and with 0.5 wt stannous chloride (SnCl2) as a catalyst under an absolute pressure of 70 Pa an at 165-170DEG; C, poly(D,L-lactic acid) (PDLLA) with an intrinsic viscosity of 0.2302 dL/g was synthesized after 10 h of melt polycondensation. This directly produced PDLLA was systematically characterized with gel perineation chromatography, Fourier transform infrared, H-1-NMR, differential scanning calorimetry, and X-ray diffraction. The weight-average molecular weight of PDLLA was 17,800 Da, and the weight-average molecular weight/number-average molecular weight ratio was 1.25. It was partly ci N'stalline, and its crystallinity was 20.8. When first applied to the Chinese traditional medicine compound prescription Osteitis no. 1 PDLLA microsphere (G-PDLLA-MS), the optimal conditions for the extraction of the effective components in three raw herbs (Herba epimedii, Fructus psora-kae, and Angelicae) and for the preparation of G-PDLLA-MS were determined with orthogonal testing. After the extractant was obtained by ethanol reflux, G-PDLLA-MS was prepared with a gelatin concentration of 8, an inner water phase/oil phase volume ratio of 1.5:1, a stirring rate of dispersion of 1000 rpm, and a PDLLA concentration of 20. Differential scanning calorimetry and scanning electron microscopy proved that G-PDLLA-MS had a good spherical shape. The practical average particle size of G-PDLLA-MS was 8.59 mu; m, and the particle sum between 2 and 12 mu; m was greater than 91; this meets the requirement for an arthritis cure. COPY; 2005 Wiley Periodicals, Inc.