Acta Phys. -Chim. Sin. ›› 2017, Vol. 33 ›› Issue (5): 1043-1050.doi: 10.3866/PKU.WHXB201702083

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CH2 Scissor and Twist Vibrations of Liquid Polyethylene Glycol——Raman Spectra and Density Functional Theory Calculations

Lei HAN1,Li PENG1,Ling-Yun CAI1,Xu-Ming ZHENG1,Fu-Shan ZHANG2,*()   

  1. 1 Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018, P. R. China
    2 Technology Center, Hengan Group, Jinjiang 362261, Fujian Province, P. R. China
  • Received:2016-11-28 Published:2017-04-20
  • Contact: Fu-Shan ZHANG E-mail:zxm@zstu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21473163);National Basic Research Program of China (973)(2013CB834604)

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Abstract:

A new method is developed to effectively study the contributions of various coexisting conformations to the actual vibrational spectrum of liquid polyethylene oxide (PEO). By defining six conformations for the-(CH2CH2O)-unit, four isomers from the combinations of all the same EO conformations [(TGT)10, (TTT)10, (TTG)10, and (GTG)10] and three isomers from the combinations of other EO conformations were constructed. Their optimized geometric structures and the corresponding vibrational frequencies were then computed. The unified standards that describe the different types of the CH2 scissor and CH2 twist vibrational modes for PEO400 are proposed through the analysis of the normal modes. The relationships between the four CH2CH2-OCH2CH2 conformations and the various CH2 scissor and CH2 twist vibrational modes and frequencies are determined, and the results are used to assign the practical vibrational spectra.

Key words: Polyethylene oxide, Conformation, Raman spectrum, Density functional theory calculation