摘要
聚乳酸材料在环境中降解成二氧化碳和水，能解决以石油为原料的聚合物因在环境中不能降解造成的环境污染；聚乳酸材料还具有优良的生物相容性，是重要的生物医用材料，用来制造可吸收的手术缝合线、骨科内固定器件、可控释放药物载体、组织工程支架等。因此，聚乳酸材料是目前研究的热点。
本研究以乳酸为原料，制备了L-丙交酯和D，L-丙交酯，以乙醇酸为原料制备了乙交酯。利用内消旋丙交酯在水中的溶解和水解的速度大于其它丙交酯的特点，用水洗和两次重结晶相结合的提纯方法，获得了高纯的L-丙交酯和D，L-丙交酯：纯丙交酯中的含水量低于0.006％，L-丙交酯旋光纯度达99.88％；同单纯的重结晶方法相比，水洗提纯方法的丙交酯回收率提高了10％以上，使用的有机溶剂少，操作简单。分别在45℃或38℃挥发溶剂，制备了具有不同晶体结构的α-乙交酯和β-乙交酯。
辛酸亚锡作为引发剂，开环聚合合成了聚丙交酯和丙交酯乙交酯共聚物，研究了引发剂浓度和聚合时间对聚合物粘均分子量的影响，获得的聚合物的最高粘均分子量超过55万。通过测定熔点、酸含量、旋光度、粘度，水分、红外光谱分析、核磁共振、气相色谱—质谱联用分析、X射线分析，确认了交酯单体的结构、纯度、物理化学性能和聚合物的分子量；用同核去偶1H-NMR谱，确定了聚L-丙交酯和聚D，L-丙交酯的链段结构。成型后的高分子材料的抗弯强度在80～160MPa之间，抗剪强度在60～110MPa之间；多孔泡沫材料的孔隙率为75％，孔径在200～400μm之间，表明合成的高分子材料可以用于制造一般的骨科可吸收内固定器件和骨组织工程支架材料。
In the circumstance, the catabolites of polylactide are CO2 and H2O which can solve the environmental pollution of petroleum polymer. As an important biomedical polymer materials , polylactide has the excellent biocompatibility which were used for absorbable suture, bone internal fixation, drug controlled release, tissue engineering etc. so polylactide is the at present.
In this paper, L-lactide and D,L-lactide were prepared from lactic acid, glycolide was prepared form glycolic acid. Using the different hydrolysis speed in the water between the meso-lactide and the other lactides, high pure L-lactide and D,L-lactide were obtained by water bath and two times recrystallization. The moisture of the pure lactide was under 0.006% and the optical purity was 99.88%. Comparing to the recrystallization method, the yield of lactide purified by water bath purifying method was increased by 10%. Glycolide was obtained with two different crystal structure of a and (3 under different temperature evaporating the dissolvent.
Polylactide and the copolymer of lactide and glycolide were obtained by ring-opening polymerization with Sn(Oct)2 as the catalyst. The effect of catalyst concentration and reaction temperature on the viscosity-average molecular weight of the polymer was discussed. The highest viscosity-average molecular weight has exceeded 55 l04 The structure, purity, physical chemistry properties of cyclic diester and molecular weight of polymer were confirmed through the fusion point,
ABSTRACT
content of carboxyl group, optical rotation, viscosity, moisture, IR spectra, 'H-NMR, GC/MS, X-ray of cyclic diester. The chain segment structure of poly(L-lactide) and poly(D,L-lactide) were confirmed through Homonuclear decoupling 'H-NMR. The bending strength of polymers were 80~160MPa, the shear strength were 60~110MPa; the porosity of porous foam materials was 75% and pore size with diameters was in the range of 200 to 400um. The result show that the polymer are fit to manufacture bone internal fixation and bone tissue scaffold materials.
引文
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