Dilute solution properties of cellulose in LiOH/urea aqueous system
Dilute solution properties of cellulose in LiOH/urea aqueous system
复制标题
DOI：
10.1002/polb.20938
复制
发表时间：
2006-11-01
影响因子：
--
通讯作者：
Zhang, Lina
中科院分区：
文献类型：
--
作者：
Cai, Jie;Liu, Yating;Zhang, Lina
纤维素在4.6 wt % LiOH/15 wt %尿素水溶液中快速溶解，预冷至-10℃，形成无色透明溶液。c -13核磁共振谱证明它是纤维素的直接溶剂，而不是衍生物水溶液体系。透射电镜结果显示纤维素分子在分子水平上在稀溶液中具有良好的分散。用激光散射和粘度法测定了纤维素在LiOH/尿素水溶液中的质量-平均分子量（MW）、均方根旋转半径(< s(2)>(1/2)(Z))和特性粘度（[eta]）。建立了纤维素在4.6 wt % LiOH/15 wt %尿素水溶液中的Mark-Houwink方程：[eta] = 3.72 × 10(-2) M-w(0.77)， M-w范围从2.7 × 10(4)到4.12 × 10(5)。纤维素在稀溶液中的滞留长度(q)、单位轮廓长度摩尔质量（M-L）和特征比(c)分别为6.1 nm、358 nm（-1）和20.8。纤维素分子参数的实验数据符合虫状链的Yamakawa-Fujii理论，表明LiOH/尿素水溶液是纤维素理想的溶剂体系。结果表明，纤维素在LiOH/尿素水溶液中以半半链形式存在。纤维素溶液在测定和贮存阶段都是稳定的。本工作提供了一种新的无色、易于制备、无毒的溶剂体系，可用于研究纤维素的链构象和分子量。(c) 2006 Wiley期刊公司[J] .高分子材料科学与工程学报，2006,31(4):393 -3101。
Cellulose was dissolved rapidly in 4.6 wt % LiOH/15 wt % urea aqueous solution and precooled to -10 degrees C to create a colorless transparent solution. C-13-NMR spectrum proved that it is a direct solvent for cellulose rather than a derivative aqueous solution system. The result from transmission electron microscope showed a good dispersion of the cellulose molecules in the dilute solution at molecular level. Weight-average molecular weight (MW), root mean square radius of gyration (< s(2)>(1/2)(Z)), and intrinsic viscosity ([eta]) of cellulose in LiOH/urea aqueous solution were examined with laser light scattering and viscometry. The Mark-Houwink equation for cellulose in 4.6 wt % LiOH/15 wt % urea aqueous solution was established to be [eta] = 3.72 x 10(-2) M-w(0.77) in the M-w region from 2.7 x 10(4) to 4.12 x 10(5). The persistence length (q), molar mass per unit contour length (M-L), and characteristic ratio (C.) of cellulose in the dilute solution were given as 6.1 nm, 358 nm(-1), and 20.8, respectively. The experimental data of the molecular parameters of cellulose agreed with the Yamakawa-Fujii theory of the worm-like chain, indicating that the LiOH/urea aqueous solution was a desirable solvent system of cellulose. The results revealed that the cellulose exists as semistiff-chains in the LiOH/urea aqueous solution. The cellulose solution was stable during measurement and storage stage. This work provided a new colorless, easy-to-prepare, and nontoxic solvent system that can be used with facilities to investigate the chain conformation and molecular weight of cellulose. (c) 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3093-3101, 2006.