Experimental and Theoretical Study on Terahertz Spectra for Regenerated Cellulose
DAI Ze-lin, XU Xiang-dong*, GU Yu, ZOU Rui-jiao, HAN Shou-sheng, PENG Yong, LIAN Yu-xiang, WANG Fu, LI Xin-rong, CHEN Zhe-geng, SUN Ming-hui, JIANG Ya-dong
State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054, China
Abstract：In this work, regenerated cellulose films were prepared with an iced dissolution method, while the physical morphologies and crystal types of the products were systematically characterized with scanning electron microscope (SEM), Fourier transform infrared(FTIR), while X-Ray Diffraction (XRD). The results demonstrate that the as-prepared continuous and uniform films are indeed cellulose Ⅱ, whose morphology and crystal type are significantly different from those of the degreased cotton. Moreover, Terahertz time domain system (THz-TDS) and FTIR were employed to measure the THz spectra of the regenerated cellulose films. Accordingly, the THz characteristic peaks for the regenerated cellulose films are experimentally identified for the first time. In addition, the increase of the THz transmittance with the decrease of the wavenumber is attributed to the existence of amorphous components in the regenerated cellulose films. Although the shapes of Far-IR spectra in the range of 100～700 cm-1 are similar, the absorption peaks of the regenerated cellulose films move to lower wavenumbers (blue shift) compared with those of the degreased cotton. Based on this, we developed a new approach to distinguish the allomorphism of cellulose Ⅱ and cellulose Iβ by Far-IR. Particularly, geometry optimization and IR calculation for the crystal structure of cellulose Ⅱ have been successfully processed by Density Functional Theory (DFT) using periodic boundary condition via CASTEP package. The calculated absorption peak positions are in good agreement with those experimentally measured. Consequently, the THz characteristic peaks of the regenerated cellulose films have been systematically and successfully assigned. Theoretical calculations reveal that the peaks at 42 and 54 cm-1 are assigned to the lattice vibration modes coupled with translational mode and rotational mode, respectively. Moreover, the absorption peaks in the range of 68～238 cm-1 are related with the torsion vibration of —CH2OH group and deformation vibration of C—H bond and O—H bond, while those in the range of 351～583 cm-1 are assigned to the skeletal vibration of C—O—C bond and pyranoid ring, and those at 611 and 670 cm-1 are originated from the out-of-plane bending vibration of O—H bond. Each absorption peak is involved in more than single vibration mode. The THz spectra presented in this work, together with the theoretical simulations, indicate that the THz responses of regenerated cellulose are closely associated with both its chemical constituents and molecular structure. These results will be helpful not only for better understanding the relations between the molecular structure of the regenerated cellulose and its THz spectrum, but also for providing valuable information for future studies on the physical mechanisms of THz responses of other partially-crystalline polymers and organic biological macromolecules.
戴泽林，许向东*，谷 雨，邹蕊矫，韩守胜，彭 勇，连宇翔，王 福，李欣荣，陈哲耕，孙铭徽，蒋亚东 . 再生纤维素太赫兹光谱的实验与理论研究 [J]. 光谱学与光谱分析, 2017, 37(03): 697-703.
DAI Ze-lin, XU Xiang-dong*, GU Yu, ZOU Rui-jiao, HAN Shou-sheng, PENG Yong, LIAN Yu-xiang, WANG Fu, LI Xin-rong, CHEN Zhe-geng, SUN Ming-hui, JIANG Ya-dong. Experimental and Theoretical Study on Terahertz Spectra for Regenerated Cellulose . SPECTROSCOPY AND SPECTRAL ANALYSIS, 2017, 37(03): 697-703.
[1] Ishikawa A, Okano T, Sugiyama J. Polymer, 1997, 38(2): 463. [2] Chung C, Lee M, Choe E K. Carbohydrate Polymers, 2004, 58(4): 417. [3] Nelson M L, O’Connor R T. Journal of Applied Polymer Science, 1964, 8(3): 1325. [4] Guo H, He M, Huang R, et al. RSC Advances, 2014, 4(101): 57945. [5] Vieira F S, Pasquini C. Analytical Chemistry, 2014, 86(8): 3780. [6] Yan C, Yang B, Yu Z. Analytical Letters, 2013, 46(6): 946. [7] Husan S K, Hasted J B, Rosen D, et al. Infrared Physics, 1984, 24(2-3): 209. [8] Cai J, Zhang L. Macromolecular Bioscience, 2005, 5(6): 539. [9] Zhang L, Ruan D, Zhou J. Industrial & Engineering Chemistry Research, 2001, 40(25): 5923. [10] Colom X, Carrillo F. European Polymer Journal, 2002, 38(11): 2225. [11] Atalla R H, Vanderhart D L. Science, 1984, 223(4633): 283. [12] Isogai A, Usuda M, Kato T, et al. Macromolecules, 1989, 22(7): 3168. [13] Liu H B, Plopper G, Earley S, et al. Biosensors and Bioelectronics, 2007, 22(6): 1075. [14] Strom U, Taylor P C. Physical Review B, 1977, 16(12): 5512. [15] Walther M, Fischer B M, Jepsen P U. Chemical Physics, 2003, 288(2): 261. [16] LIU Yi-ke, LIU Yu-tong, XU Xiang-dong, et al(刘一客, 刘禹彤, 许向东, 等). Acta Physica Sinica(物理学报), 2014, 64(6): 68701. [17] Kolpak F J, Blackwell J. Macromolecules, 1976, 9(2): 273. [18] Nishiyama Y, Langan P, Chanzy H. Journal of the American Chemical Society, 2002, 124(31): 9074. [19] WANG Guo, WANG Wei-ning(王 果, 王卫宁). Acta Physico-Chemica Sinica(物理化学学报), 2012, 28(7): 1579. [20] Jepsen P U, Clark S J. Chemical Physics Letters, 2007, 442(4): 275. [21] Szymańska-Chargot M, Cybulska J, Zdunek A. Sensors, 2011, 11(6): 5543.
