Influence of Cellulose on Ion Diffusivity in 1-Ethyl-3-Methyl-Imidazolium Acetate Cellulose Solutions
Influence of Cellulose on Ion Diffusivity in 1-Ethyl-3-Methyl-Imidazolium Acetate Cellulose Solutions
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DOI：
10.1021/bm1006807
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发表时间：
2010-11-01
影响因子：
6.2
通讯作者：
Ries, Michael E.
中科院分区：
文献类型：
--
作者：
Lovell, Christopher S.;Walker, Adam;Ries, Michael E.
用脉冲场梯度H-1 NMR研究了微晶纤维素在1-乙基-3-甲基咪唑乙酸盐中的溶液。在所有情况下，发现几何上较大的阳离子比较小的阴离子更快地子句。Arrhenius温度分析已被应用到离子扩散系数给出激活能。这些解决方案的扩散和公布的粘度数据显示遵循斯托克斯-爱因斯坦关系，给出1.6埃（阳离子）和1.8埃（阴离子）的流体动力学半径。理论的障碍，自由体积和流体动力学效应的溶剂扩散已被应用。Mackie-Meares和Maxwell-Schlemke阻塞模型仅在假设一定比例的离子与聚合物结合时才提供正确的趋势。从该级分显示，最大可溶解纤维素浓度类似于27%w/w，这与该离子液体中纤维素的最高已知制备浓度一致。Phillies的流体动力学模型被发现给纤维素浓度依赖的离子扩散系数的最佳描述。
Solutions of microcrystalline cellulose in 1-ethyl-3-methyl-imidazolium acetate have been investigated using pulsed-field gradient H-1 NMR. In all cases the geometrically larger cation was found to clause faster than the smaller anion. Arrhenius temperature analysis has been applied to the ion diffusivities giving activation energies. The diffusion and published viscosity data for these solutions were shown to follow the Stokes Einstein relationship, giving hydrodynamic radii of 1.6 angstrom (cation) and 1.8 angstrom (anion). Theories for obstruction, free-volume and hydrodynamic effects on solvent diffusion have been applied. The Mackie-Meares and Maxwell-Fricke obstruction models provided a correct trend only when assuming a certain fraction of ions are bound to the polymer. From this fraction it was shown that the maximum dissolvable cellulose concentration is similar to 27% w/w, which is consistent with the highest known prepared concentration of cellulose in this ionic liquid. The Phillies' hydrodynamic model is found to give the best description for the cellulose concentration dependence of the ion diffusivities.