DFT study of the influence of acetyl groups of cellulose acetate on its intrinsic birefringence and wavelength dependence
DFT study of the influence of acetyl groups of cellulose acetate on its intrinsic birefringence and wavelength dependence
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DOI：
10.1016/j.carbpol.2018.11.074
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发表时间：
2019-03-01
影响因子：
11.2
通讯作者：
Ueda, Kazuyoshi
中科院分区：
文献类型：
--
作者：
Hayakawa, Daichi;Gouda, Hiroaki;Ueda, Kazuyoshi
使用密度泛函理论 (DFT) 研究了醋酸纤维素 (CA) 的乙酰基对其固有双折射及其波长依赖性的影响。计算中使用了七种取代度 (DS) 和取代位点不同的 CA 重复单元模型。结果表明，固有双折射（Delta n 度）及其波长依赖性显着取决于 C6 乙酰基的构象。此外，CA 薄膜的固有双折射被估计为构象异构体计算的 Delta n 度值的整体平均值。 CA 的 DS 增加导致更负的本征双折射和更大的波长依赖性。计算结果与实验结果具有良好的定性一致性，表明构象多样性和/或其控制将是含 CA 光学薄膜设计的重要因素。
The effect of the acetyl groups of cellulose acetate (CA) on its intrinsic birefringence and its wavelength dependence was investigated using density functional theory (DFT). Seven types of CA repeating-unit models that differ in their degree of substitution (DS) and substitution sites were used in the calculations. The results suggested that the intrinsic birefringence (Delta n degrees) and its wavelength dependence significantly depended on the conformations of the acetyl group at C6. Additionally, the intrinsic birefringence of CA films was estimated as the ensemble average of the calculated Delta n degrees values of the conformers. The increase in the DS of CA led to a more negative intrinsic birefringence and a larger wavelength dependence. The computational results were in good qualitative agreement with the experimental results and suggested that conformational variety and/or its control would be important factors for the design of optical films containing CA.