淀粉-丙烯酸钠接枝共聚物的固体高分辨核磁共振研究

Solid State NMR Study of Starch-sodium Acrylate Grafted Copolymer

运用固体高分辨核磁共振技术,通过测量13C魔角旋转/交叉极化(CP/MAS)谱、1H自旋-晶格弛豫时间T1及旋转坐标系中的自旋-晶格弛豫时间T1ρ,对一系列淀粉-丙烯酸钠接枝共聚物的相结构进行了研究,并与淀粉、均聚丙烯酸钠及两者共混物的实验结果进行了比较.结果表明,接枝共聚导致了淀粉结晶度的明显降低;在共混物和接枝共聚物中,淀粉和聚丙烯酸钠组分都具有纳米尺度的相容性,由于接枝的效应,接枝共聚物中两个组分表现出比共混物更高的相容水平.

The domaln-structure of a series of starch/poly （ sodium acrylate） grafted samples, in comparison with starch, poly（ sodium acrylate） and starch/poly （sodium acrylate） blend, was studied by high-resolutlon solid-state ^13C NMR spectroscopy at room temperature. The crystallinity of starch was found to decrease greatly in the grafted and blended samples. The obtained values of ^1 H spin-lattlce relaxation time in rotating frame T1p and ^1 H spin-lattice relaxation time T1 showed that the starch and poly （sodium acrylate） components in both grafted and blended samples have the compatibility on nanometer scale. In the ^13C CP/MAS spectra, the chemical shift of the carbonyl group of poly（ sodium acrylate） is found to be dependent on the composition of the grafted samples. This result indicates further that the starch and the poly（ sodium acrylate） components of the grafted samples exhibita compatibility at the molecular level, which is better than that of the blend sample.