Solid-State 13C NMR Studies of the Structure and Chain Conformation of Thermotropic Liquid Crystalline Polyether Crystallized from the Liquid Crystalline Glassy Phase

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Abstract

The structure and chain conformation of the form β sample newly crystallized from the liquid crystalline (LC) glassy phase have been investigated for a main-chain thermotropic LC polyether, which was polymerized from 3,3′-dimethyl-4,4′-hydroxyl-biphenyl and 1,10-dibromodecane, by solid-state 13C NMR spectroscopy. The 13C spin–lattice relaxation analyses reveal that there exist two components with different T1C values, which correspond to the crystalline and noncrystalline (supercooled liquid crystalline) components. By employing such differences in T1C, the spectra of the respective components are separately recorded, and the conformations of their CH2 sequences are evaluated by considering the γ-gauche effect on the 13C chemical shifts. As a result, the crystalline component is found to adopt the txxxtxxxt′ conformation whereas another conformation of txxxxxxxt′ is preferably induced in the noncrystalline region, where t, t′, and x indicate trans, trans-rich and transgauche exchange conformations, respectively. These conformations are markedly different from txtxtxtxt and xxxxxxxxx in the corresponding components for the form α sample previously reported, probably reflecting the difference in crystallization from different nematic phases Nα and Nβ. Moreover, molecular motion for the mesogen units and the spacer CH2 sequences has been examined by the chemical shift anisotropy (CSA) analysis based on the magic angle turning (MAT) method. The mesogenic phenylene carbons are found to undergo rather restricted flip motion with amplitudes less than 30° around the bond axis in both crystalline and noncrystalline regions, while the flip rates associated with the 13C spin–lattice relaxation may be greatly different in the two regions. The CSA spectrum of the spacer CH2 carbons significantly narrows possibly as a result of the specific change in chain conformation in the crystalline and noncrystalline regions.

References

  1. 1

    H. Ishida and F. Horii, Macromolecules, 34, 7751 (2001).

  2. 2

    Liquid Crystallinity in Polymers. Principles and Fundamental Properties,” A. Ciferri, Ed., VCH Publishers, New York, N.Y., 1991.

  3. 3

    Liquid-Crystalline Polymer Systems. Technological Advances,” A. I. Isayev, T. Kyu, and S. Z. D. Cheng, Ed., ACS Symp. Series 632, Am. Chem. Soc., Washington, D.C., 1996.

  4. 4

    Handbook of Liquid Crystal Research,” P. J. Collings and J. S. Patel, Ed., Oxford Univ. Press, New York, N.Y., 1997.

  5. 5

    Structure and Properties of Oriented Polymers,” I. M. Ward, Ed., Chapman & Hall, London, 1997.

  6. 6

    Thermotropic Liquid Crystal Polymers,” T.-S. Chung, Ed., Technomic, Lancaster, 2001.

  7. 7

    M. Murakami, H. Ishida, M. Miyazaki, H. Kaji, and F. Horii, Macromolecules, 36, 4160 (2003).

  8. 8

    M. Murakami, H. Ishida, H. Kaji, and F. Horii, Polym. J., 35, 951 (2003).

  9. 9

    M. Ooyama, T. Yamamoto, K. Nozaki, and F. Horii, Polym. Prepr. Jpn., 52, 549 (2003).

  10. 10

    H. Ishida and F. Horii, Macromolecules, 35, 5550 (2002).

  11. 11

    Y. Ohira, F. Horii, and T. Nakaoki, Macromolecules, 34, 1655 (2001).

  12. 12

    K. Kuwabara, H. Kaji, M. Tsuji, and F. Horii, Macromolecules, 33, 8520 (2000).

  13. 13

    K. Masuda and F. Horii, Macromolecules, 31, 5810 (1998).

  14. 14

    Z. Gan, J. Am. Chem. Soc., 114, 8307 (1992).

  15. 15

    J. Z. Hu, A. M. Orendt, D. W. R. J. P. Alderman, C. H. Ye, and D. M. Grant, Solid State Nucl. Magn. Reson., 3, 181 (1994).

  16. 16

    D. A. Torchia, J. Magn. Reson., 44, 117 (1981).

  17. 17

    A. E. Tonelli, “NMR Spectroscopy and Polymer Microstructure: The Conformational Connection,” VCH Publishers, New York, N.Y., 1989.

  18. 18

    S. Ando, T. Hironaka, H. Kurosu, and I. Ando, Magn. Reson. Chem., 38, 241 (2000).

  19. 19

    T. M. Duncan, “A Compilation of Chemical Shift Anisotropies,” Farragut Press, Chicago, IL, 1990.

  20. 20

    M. Mehring, “Principles of High Resolution NMR in Solids,” Springer-Verlag, Berlin, 1993.

  21. 21

    F. Horii, Bull. Inst. Chem. Res., Kyoto Univ., 70, 198 (1992).

  22. 22

    D. H. Barich, R. J. Pugmire, D. M. Grant, and R. J. Iuliucci, J. Phys. Chem. A, 105, 6780 (2001).

  23. 23

    P. B. Murphy, T. Taki, B. C. Gerstein, P. M. Henrichs, and D. J. Massa, J. Magn. Reson., 49, 99 (1982).

  24. 24

    W. W. Fleming, C. A. Fyfe, R. D. Kendrick, J. R. Lyerla, H. Vanni, and C. S. Yannoni, “Polymer Characterization by ESR and NMR,” A. E. Woodward and F. A. Bovey, Ed., ACS Symp. Ser. No. 142, 1980, p 193.

  25. 25

    A. Pines, M. G. Gibby, and J. S. Waugh, Chem. Phys. Lett., 15, 373 (1972).

  26. 26

    J. Van Dogen Torman and W. S. Veeman, J. Chem. Phys., 68, 3233 (1978).

  27. 27

    D. L. VanderHart, J. Chem. Phys., 64, 830 (1976).

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Keywords

  • Liquid Crystalline Polymer
  • Polyether
  • Solid-State 13C NMR
  • Liquid Crystalline Glass
  • Conformation
  • Co-planarity
  • Molecular Motion

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