Chain Dimensions and Stiffness of Cellulosic and Amylosic Chains in an Ionic Liquid: Cellulose, Amylose, and an Amylose Carbamate in BmimCl
Chain Dimensions and Stiffness of Cellulosic and Amylosic Chains in an Ionic Liquid: Cellulose, Amylose, and an Amylose Carbamate in BmimCl
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DOI：
10.1021/acs.macromol.7b00389
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发表时间：
2017-05
期刊：
影响因子：
5.5
通讯作者：
Xinyue Jiang;S. Kitamura;Takahiro Sato;K. Terao
中科院分区：
文献类型：
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作者：
Xinyue Jiang;S. Kitamura;Takahiro Sato;K. Terao
在25 °C下对离子液体[氯化1-丁基-3-甲基咪唑鎓（BmimCl）]中的纤维素、直链淀粉和直链淀粉三（乙基氨基甲酸酯）（ATEC）进行小角X射线散射测量，以确定z-平均均方回转半径ε S2 ε z和颗粒散射函数P（q）。根据蠕虫状链模型分析所获得的数据，以估计Kuhn段长度λ-1（刚度参数，相当于持续长度的两倍）和每个残基h的螺旋节距（或螺旋上升）。纤维素、直链淀粉和ATEC的链刚度（λ-1）分别为7 ± 1 nm、3.5 ± 0.5 nm和7.5 ± 0.5 nm。这些值几乎相同或略小于先前研究的系统，表明这些聚合物在离子液体中具有相对高的柔性。这是合理的假设，破坏分子内氢键的多糖使主链在离子液体中相当灵活。
Small-angle X-ray scattering measurements were made for cellulose, amylose, and amylose tris(ethylcarbamate) (ATEC) in an ionic liquid [1-butyl-3-methylimidazolium chloride (BmimCl)] at 25 °C to determine z-average mean-square radius of gyration ⟨S2⟩z and the particle scattering function P(q). The obtained data were analyzed in terms of the wormlike chain model to estimate the Kuhn segment length λ–1 (the stiffness parameter, equivalent to twice of the persistence length) and the helix pitch (or helix rise) per residue h. The chain stiffness (λ–1) was determined to be 7 ± 1 nm for cellulose, 3.5 ± 0.5 nm for amylose, and 7.5 ± 0.5 nm for ATEC. These values are almost the same or somewhat smaller than those of previously investigated systems, indicating these polymers have relatively high flexibility in the ionic liquid. It is reasonable to suppose that disruption of intramolecular hydrogen bonds of polysaccharide makes the main chain rather flexible in the ionic liquid.