聚乳酸/明胶共混膜的固体核磁共振研究

A SOLID STATE ^(13)C/CP MAS NMR STUDY ON POLY(LACTIC ACID)/GELATIN BLEND MEMBRANES

以DMSO作为聚乳酸(PLLA)和明胶的共溶剂,采用浇铸法将PLLA与明胶混合在一起。X射线衍射结果表明PLLA用DMSO溶解后,在重新干燥的过程中,PLLA的堆积结构会发生变化,半结晶态的PLLA变成无定形态。使用固体13CCP/MASNMR测定了原料PLLA以及不同比例的PLLA/明胶共混膜的弛豫时间,发现PLLA100及所有共混膜的弛豫时间与原料PLLA相比,显著增加,分子运动加剧。进一步证明了PLLA在用DMSO处理后由半晶态转变成了无定形态,明胶的加入,不影响聚乳酸的结晶结构。

Poly(lactic acid) (PLLA) and gelatin were successfully blended through solution casting method using dimethyl sulfoxide(DMSO) as a co-solvent. X-ray diffraction results indicate that the stacking structure of PLLA is altered, and semi-crystalline PLLA is changed into amorphous structure during the dissolved PLLA in DMSO is redried. The relaxation time of raw PLLA and PLLA/gelatin blend membranes with various ratios were measured by solid state (^(13)C CP/)MAS NMR. It shows that the relaxation time of PLLA100 and other blend samples increase compared to those of original PLLA, suggesting an increased molecular motion, which further demonstrates that semi-crystalline PLLA has become an amorphous structure after it is dissolved in DMSO and redried.