Elastomers and Composites

The Rubber Society of Korea (한국고무학회)
권호 표지
DOI QR코드

DOI QR Code

Synthesis and Properties of Combined Main-Chain/Side-Chain Liquid Crystalline Polymers with Cholesteryl and Azobenzene Groups

  • Gu, Su-Jin (Division of Advanced Materials Science and Engineering, Kongju National University) ;
  • Lee, Eung-Jae (Dept. of Bioenvironmental & Chemical Engineering, Chosun College of Science & Technology) ;
  • Bang, Moon-Soo (Division of Advanced Materials Science and Engineering, Kongju National University)
  • Received : 2018.12.17
  • Accepted : 2018.12.26
  • Published : 2019.03.31
Download PDF
⟨ Previous Next ⟩

Abstract

Main-chain/side-chain liquid crystalline polymers (MCSCLCPs) combined with an azobenzene group and a cholesteryl group were synthesized to impart light and temperature sensitivity to the polymer. The polymers were designed with the azobenzene unit as the mesogenic group of the main-chain and various compositions of the azobenzene and cholesteryl units as the mesogenic group of the side-chain. The chemical structures and physical properties of the synthesized polymers were investigated by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, differential scanning calorimetry, thermogravimetric analysis, polarized optical microscopy, and ultraviolet-visible (UV-Vis) spectroscopy. All the MCSCLCPs were amorphous and exhibited enantiotropic liquid crystal phases; these polymers achieved the nematic phase with increasing content of the azobenzene group and exhibited the cholesteric phase with weak liquid crystallinity as the content of the cholesteryl group was increased. Furthermore, the polymers containing the azobenzene group showed photoisomerization when exposed to UV-Vis light, and the CP-A3C7 and CP-A5C5 polymers exhibited thermochromism in the temperature range of the liquid crystal phase.

Keywords

HKGMCJ_2019_v54n1_14_f0001.png 이미지

Figure 1. Chemical structures of monomers.

HKGMCJ_2019_v54n1_14_f0002.png 이미지

Figure 2. Synthesis routes of monomer DHAB.

HKGMCJ_2019_v54n1_14_f0003.png 이미지

Figure 3. Synthesis scheme of polymers.

HKGMCJ_2019_v54n1_14_f0004.png 이미지

Figure 4. FT-IR spectra of polymers (KBr).

HKGMCJ_2019_v54n1_14_f0005.png 이미지

Figure 5. 1H-NMR spectra of polymers (TFA-d or TCE-d2).

HKGMCJ_2019_v54n1_14_f0006.png 이미지

Figure 6. DSC thermograms of polymers.

HKGMCJ_2019_v54n1_14_f0007.png 이미지

Figure 7. TGA thermograms of polymers.

HKGMCJ_2019_v54n1_14_f0008.png 이미지

Figure 8. DTG curves of polymers.

HKGMCJ_2019_v54n1_14_f0009.png 이미지

Figure 9. Cross-polarized optical micrographs of polymers(magnification of x50).

HKGMCJ_2019_v54n1_14_f0010.png 이미지

Figure 10. UV/Vis absorption spectra of polymers.

Table 1. Phasea Transition Temperatures of Monomers

HKGMCJ_2019_v54n1_14_t0001.png 이미지

Table 2. Yield, and the Composition of the Monomers used in theSynthesis of Polymers

HKGMCJ_2019_v54n1_14_t0002.png 이미지

Table 3. Inherent Viscositya and Solubility Test of Polymers

HKGMCJ_2019_v54n1_14_t0003.png 이미지

Table 4. DSC and TGA Data of Polymers

HKGMCJ_2019_v54n1_14_t0004.png 이미지

Table 5. Photoisomerization Rate Constants of Polymers in THF

HKGMCJ_2019_v54n1_14_t0005.png 이미지

References

  1. B. Reck and H. Ringsdorf, "Combined liquid-crystalline polymers: rigid rod and semi-flexible main chain polyesters with lateral mesogenic groups", Macromol Rapid Commun., 7, 389 (1986). https://doi.org/10.1002/marc.1986.030070612
  2. M. Sato and M. Mizoi, "Relationships between structures and liquid crystalline and optical properties in combined-type copolyisophthalates having nitro- and methoxyazobenzene units and aliphatic spacers in the side chain", Polym. J. (Tokyo, Japan) 36, 607 (2004). https://doi.org/10.1295/polymj.36.607
  3. R. Zentel and M. Brehmer, "Combined LC main chain/side chain polymers", Acta Polymer, 47, 141 (1996). https://doi.org/10.1002/actp.1996.010470402
  4. X. L. Piao, J. S. Kim, Y. K. Yun, and J. I. Jin, "Combined type liquid crystalline polymers composed of poly(p-phenylene terephthalate) main chain and azobenzene mesogenic side groups attached through polymethylene spacers", Macromolecules, 30, 2294 (1997). https://doi.org/10.1021/ma961649k
  5. S. W. Cha, J. I. Jin, D. C. Kim, and W. C. Zin, "Combined type liquid crystalline poly(oxy-1,4-phenyleneoxyterephthaloyl)s bearing cholesterol pendants attached through polymethylene spacers", Macromolecules, 34, 5342 (2001). https://doi.org/10.1021/ma001861v
  6. I. Sage, "Thermochromic liquid crystals", Liq. Cryst. 38, 11 (2011). https://doi.org/10.1080/02678292.2011.631302
  7. A. Seeboth, D. Loetzsch, and R. Ruhmann, "Piezochromic polymer materials displaying pressure changes in barranges", Am. J. Mater. Sci., 1, 139 (2012). https://doi.org/10.5923/j.materials.20110102.23
  8. W. E. Lee, C. L. Lee, T. Sakaguchi, M. Fujiki, and G. Kwak, "Piezochromic fluorescence in liquid crystalline conjugated polymers", Chem. Commun., 47, 3526 (2011). https://doi.org/10.1039/c0cc04811a
  9. I. Nishiyama, T. Yamamoto, J. Yamamoto, J. W. Goodby, and H. Yokoyama, "Achiral non-branched rod-shaped liquid crystals showing anticlinic smectic phase", J. Mater. Chem., 13, 1868 (2003). https://doi.org/10.1039/b304274j
  10. M. R. Meadows, M. A. Handschy, and N. A. Clark, "Electro-optic switching using total internal reflection by a ferroelectric liquid crystal", Appl. Phys. Lett., 54, 1394 (1989). https://doi.org/10.1063/1.100677
  11. M. Kleman, "Liquid crystals: the fourth state of matter", Acta. Crystallogr. A., 37, 607 (1981). https://doi.org/10.1107/S056773948100140X
  12. L. V. D. Werff, I. L. Kyratzis, A. Robinson, R. Cranston, G. Peeters, M. O'Shea, and L. Nichols, "Thermochromic composite fibres containing liquid crystals formed via melt extrusion", J. Mater. Sci., 48, 5005 (2013). https://doi.org/10.1007/s10853-013-7287-8
  13. H. J. Kim, "Effect of the position of azobenzene moiety on the light-driven anisotropic actuating behavior of polyvinylalcohol polymer blend films", Appl. Chem. Eng., 23, 65 (2012).
  14. J. R. Park, S. J. Gu, D. S. Yoon, M. S. Bang, and J. K. Choi, "Synthesis and properties of symmetrical di-azomesogenic liquid crystal compounds with terminal substituents", Appl. Chem. Eng., 26, 698 (2015). https://doi.org/10.14478/ace.2015.1100
  15. J. R. Park, K. Y. Cho, and M. S. Bang, "Synthesis and properties of unsymmetrical dimesogenic liquid crystal compounds containing lateral substituent", Appl. Chem. Eng., 26 , 280 (2015). https://doi.org/10.14478/ace.2015.1024
  16. S. Alazaroaie, V. Toader, I. Carlescu, K. Kazmierski, D. Scutaru, N. Hurduc, and C. I. Simionescu, "Liquid crystalline polymers 14. synthesis and thermal behaviour of some polyethers containing azo-mesogens", Eur. Polym. J., 39, 1333 (2003). https://doi.org/10.1016/S0014-3057(03)00002-8
  17. C. J. Barrett, J. I. Mamiya, K. G. Yager, and T. Ikeda, "Photomechanical effects in azobenzene-containing soft materials", Soft Matter, 3, 1205 (2007). https://doi.org/10.1039/b713608k
  18. N. Tamaoki, Y. Aoki, M. Moriyama, and M. Kidowaki, "Photochemical phase transition and molecular realignment of glass-forming liquid crystals containing cholesterol/azobenzene dimesogenic compounds", Chem. Mater., 15, 719 (2003). https://doi.org/10.1021/cm020234c
  19. W. L. F. Armarego and C. L. L. Chai, "Purification of laboratory chemicals", 5th Ed., Elsevier Science, USA, (2003).
  20. M. Z. Alam, A. Shibahara, T. Ogata, and S. Kurihara, "Synthesis of azobenzene-functionalized star polymers via RAFT and their photoresponsive properties", Polymer, 52, 3696 (2011). https://doi.org/10.1016/j.polymer.2011.06.035
  21. F. Higashi, T. Mashimo, and I. Takahashi, "Preparation of aromatic polyesters by direct polycondenastion with thionyl chloride in pyridine", J. Polym. Sci. Polym. Chem. Ed., 24, 91 (1986).
  22. J. R. Park, K. Y. Cho, and M. S. Bang, "Synthesis and properties of liquid crystalline polyesters with X-shaped mesogenic group in main chain", Appl. Chem. Eng., 25 , 47 (2014). https://doi.org/10.14478/ace.2013.1101
  23. This work is based on the thesis submitted by S. J. Gu for M. Eng. degree, Kongju University, Cheonan, Korea, (2016).