Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (11): 1010-1014.doi: 10.3866/PKU.WHXB20031105

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Vibrational Modes Analysis of Poly (vinylidene fluoride) All-trans Molecular Chain

Li Ji-Chao;Wang Chun-Lei;Zhong Wei-Lie   

  1. School of Physics and Microelectronics, Shandong University, Jinan 250100
  • Received:2003-04-01 Revised:2003-06-30 Published:2003-11-15

Abstract: Ab initio molecular orbital calculation was employed to optimized the geometry structure of poly (vinylidine fluoride) (PVDF) all-trans molecule. The calculated result is consistent with that of experiment. In our calculation, two different values of bond angle C-C-C were found, i.e.112.8° and 113.3°.The infrared intensity spectrum was obtained from frequencies calculation of the all-trans molecule. In the range of 400~4 000 cm-1,the IR spectra of polarized and unpolarized β-phase PVDF film (30 μm thick) have been measured. The calculated IR intensity spectrum is in good agreement with observed IR spectrum. The vibrational modes in the range of 400~4 000 cm-1 were divided into six series, series Ⅰ(544~415 cm-1), series Ⅱ(913~792 cm-1), series Ⅲ(1 353~998 cm-1), series Ⅳ(1 458~1 361 cm-1), seriesⅤand Ⅵ. Only series Ⅲ of all the vibrational modes causes the change of the dipole moment of PVDF molecule, and is related to the spontaneous polarization.

Key words: IR spectrum, PVDF, Vibrational modes, Ab initio molecular orbital calculation