Structural analysis of native cellulose and its derivatives by direct imaging of molecular chains

经过4年的深入研究，取得了以下成果：1)用电子衍射法研究了2种天然纤维素的电子衍射谱，即细菌-瓦伦型和棉麻型。它们分别被归类为三斜相和单斜相的混合相和单斜相。2)三斜单位中只有一条链。因此，一个微纤丝中的所有链条都具有相同的政治性。由此提出了一种全新的模型，该模型可以很好地替代Honjo-Watanbe的8链单元电池。3)指出了针叶木、阔叶木、竹子等木质纤维在衍射强度和间距数据上的差异。根据这些数据进行的判别分析表明，17种针叶木材和61种阔叶木材的综纤维素都属于棉麻型，但其中有一部分(15种针叶木材和7种阔叶木)在提纯前曾被归类为细菌-瓦洛瓦型。然而，软木和硬木之间仍然存在一定的差异。4)纤维素的丝光，即将纤维素I转化为纤维素II，是一个不可逆转的过程。对溶胀初期的中间结晶碱性纤维素的研究表明，完全溶胀的纤维素不能再转化为纤维素。5)用电子显微镜和X射线衍射法研究了分散微晶纤维素的丝光过程。晶态的变化伴随着明显的形态变化，如沿微纤丝形成的裂纹和珠状颗粒的形成。6)研究了纤维轴与磁场垂直的纤维素微晶水悬浮液在强磁场作用下的抗磁取向行为。

Following results were generated during 4 years of intensive research.1) 2 types of native celluloses categorized by ^<13>C-NMR, namely the Bacterial-Valonia type and the Cotton-Ramie type, were investigated by electron diffraction. They were assigned to the mixtwe of triclinic and monoclinc phases and the single phase of monoclinic, respectively. 2) The triclinic unit contained only one chain in it. Accordingly all the chains in one microfibril had the same polifity. The entirely new model were thereby proposed, which was a good alternative of 8-chain unit cell by Honjo-Watanbe. 3) Among woody celluloses such as those from softwoods, hardwoods, and bamboos, we have pointed out the difference in their diffraction intensities and dspacing data. The discriminant analyses based on those data showed that the holocelluloses of woody samples (17 softwoods and 61 hardwoods) were all categafift to the Cotton-Ramie type, although some of them (15 softwoods and 7 hardwoods) were once classified to the Bacterial-Valowa type before purification. There still remains, however, certain differences between softwoods and hardwoods. 4) Mercerization of cellulose, the transformation of cellulose I into II, is known to be an irreversible process. Having investigated intermediate crystalline alkaline celluloses in the early stage of swelling, we concluded that the fully swollen cellulose cannot go back to cellulose I. 5) Mercerization of dispersed microcrystalline cellulose was investigated by electron microscopy and x-ray diffraction. The change of crystalline state accompanied remarkable morphological changes such as the formation of cracks along microfibrils and the formation of bead-like particles. 6) The diamagnetic orientation behavior of the aqueous suspension of cellulose microcrystals was investigated When the strong magnetic field was applied, the crystals oriented perfectly, being their fiber axes perpendicular to the magnetic field.