화학공학소재연구정보센터
홈 로그인 로그아웃 연락처 사이트맵
Applied Chemistry for Engineering, Vol.21, No.2, 230-237, April, 2010
Export Citation
α,ω-비스(4-니트로아조벤젠-4'-카보닐옥시)알칸들의 열방성 액정 거동
Thermotropic Liquid Crystalline Behavior of α,ω-Bis(4-nitroazobenzene-4'-carbonyloxy)alkanes
정승용, 황동준, 마영대†
  • 단국대학교 고분자공학과
Seung Yong Jeong, Dong Jun Hwang, and Yung Dae Ma†
  • Center for Photofunctional Energy Materials, Dankook University, Gyeongi-do 448-701, Korea
E-mail:
초록
선상의 액정 다이머 동족체들인 α,ω-비스(4-니트로아조벤젠-4'-카보닐옥시)알칸들(NATWESn, n = 2∼8, 10, 유연격자 중의 메틸렌 단위들의 수)을 합성함과 동시에 이들의 열적 거동을 검토하였다. 모든 다이머들은 쌍방성 네마틱 상들을 형성하였다. 다이머들의 네마틱 상에서 액체 상으로의 전이온도들, 그리고 상 전이시의 엔트로피 변화는 n의 함수로서 커다란 홀수-짝수 효과를 나타냈다. 이러한 거동은 유연격자의 홀수-짝수의 변화에 의한 유연격자의 평균적인 형태변화의 견지에서 합리적으로 설명된다. NATWESn이 나타내는 네마틱 상의 열적 안정성과 질서도, 그리고 홀수-짝수의 크기는 니트로아 조벤젠 그룹을 폴리메틸렌 유연격자를 통하여 에테르 결합으로 도입시켜 얻은 대칭 다이머들의 결과들과 거의 유사한 반면 모노메소겐 화합물들인 4-{4'-(니트로페닐아조펜옥시}알카노일 클로라이드들, 그리고 곁사슬형 액정 고분자인 폴리 [1-{4-(4'-니트로페닐아조)펜옥시카보닐알카노일옥시}에틸렌]들의 결과들에 비해 판이하였다. 이들의 결과를 Imrie에 의한 ‘virtual trimer model’의 견지에서 검토하였다.
A homologous series of linear liquid crystal dimers, α,ω-bis(4-nitroazobenzene-4'-carbonyloxy)alkanes (NATWESn, n = 2∼ 8, 10, the number of methylene units in the spacer) have been synthesized, and the thermal behavior of the series has been investigated. All the dimers formed enantiotropic nematic phases. The nematic-isotropic transition temperatures of the dimers and their entropy variation at the phase transition showed a large odd-even effect as a function of n. This behavior was rationalized in terms of the change in the average shape of the spacer on varing the parity of the spacer. The thermal stability and degree of order in the nematic phase and the magnitude of the odd-even effect of NATWESn were very similar to those of the corresponding ether compounds, while they were significantly different from those of the monomesogenic compounds, 4-{4'-(nitrophenylazo)phenoxy}alkanoyl chlorides and the side-chain liquid-crystalline polymers, the poly[1-{4-(4'-nitrophenylazo) phenoxycarbonylalkanoyloxy}ethylene]s. The results were discussed in terms of the ‘virtual trimer model’ by Imrie.
Keywords:nitroazobenzene;symmetric dimer;odd-even effect;nematic phase;spacer length;ester linkage
  1. Brehmer L, Polymer Sensors and Actuators, eds. Osada Y, De. Rossi D, 62, Springer-Verlag, Berlin (2002)
  2. Shibaev V, Bobrovsky A, Boiko N, Prog. Polym. Sci., 28, 729 (2003)
  3. Milla VA, Tamaoki N, Chem. Soc. Rev., 33, 76 (2004)
  4. Harwood SM, Toyne KJ, Goodby JW, Parsely M, Gray GW, Liq. Cryst., 27, 443 (2000)
  5. Jin JI, Mol. Cryst. Liq. Cryst., 267, 249 (1995)
  6. Imrie CT, Luckhurst GR, Handbook of Liquid Crystals, eds. Demus D, Goodby J, Gray GW, Spiess HW, Vill V, 2B, 801, Wiley-VCH, Weinheim-New York (1998)
  7. Cha SW, Jin JI, Laguerre M, Achard MF, Hardouin F, Liq, Cryst, 26, 1325 (1999)
  8. Milla VA, Tamaoki N, Chem. Mater., 15, 3237 (2003)
  9. Milla VA, Tamaoki N, J. Mater. Chem., 13, 219 (2003)
  10. Milla VA, Aoki Y, Moriyama M, Kidowaki M, Chem. Mater., 15, 719 (2003)
  11. Lee JW, Park YS, Jin JI, Achard MF, Hardouin F, J. Mater. Chem., 13, 1367 (2003)
  12. Kim KN, Do ED, Kwon YW, Jin JI, Liq. Cryst., 32, 229 (2005)
  13. Wu C, Mater, Lett., 61, 1380 (2007)
  14. Percec V, Pugh C, Side Chain Liquid Crystal Polymers, ed. McArdle, 30, Chapman and Hall, Inc., New York (1989)
  15. Pugh C, Kiste AL, Handbook of Liquid Crystals, eds. Demus D, Goodby J, Gray GW, Spiess HW, Vill V, 3, 123, Wiley-VCH, Weinheim-New York (1998)
  16. Imrie CT, Karasz FE, Attard GS, Macromolecules, 26, 545 (1993)
  17. Imrie CT, Karasz FE, Attard GS, Macromolecules, 26, 3803 (1993)
  18. Jeong SY, Ma YD, Polym.(Korea), 30(1), 35 (2006)
  19. Jeong SY, Ma YD, Polym.(Korea), 32(5), 489 (2008)
  20. Jeong SY, Lee JY, Ma YD, Polym.(Korea), 33(4), 297 (2009)
  21. Jeong SY, Ma YD, J. Korean Ind. Eng. Chem., 19(5), 504 (2008)
  22. Attard GS, Garnett S, Hickman CG, Imrie CT, Taylor L, Liq Cryst., 7, 495 (1990)
  23. Jeong SY, Ma YD, Polym.(Korea), 31(1), 37 (2007)
  24. Henderson PA, Cook AG, Imrie CT, Liq, Cryst, 31, 1427 (2004)
  25. Niori T, Adachi S, Watanabe J, Liq. Cryst., 19, 139 (1995)
  26. Blatch AE, Luckhurst GR, Liq. Cryst., 27, 775 (2000)
  27. Gray GW, The Molecular Physics of Liquid Crystals, eds. Luckhurst GR, Gray GW, 1, Academic Press, New York (1979)
  28. Dowell F, Martire DE, J. Chem. Phys., 68, 1094 (1979)
  29. Imrie CT, Luckhurst GR, J. Mater. Chem., 8, 1339 (1998)
  30. Jeong SY, Ma YD, Chemical Materials (Dankook University), 4, 19 (2007)
  31. Jeong SY, Ma YD, Polym.(Korea), 33(2), 144 (2009)
  32. Imrie CT, Karasz FE, Attard GS, Macromolecules, 25, 1278 (1992)
  33. Craig AA, Winchester I, Madden PC, Larcey P, Hamley IW, Imrie CT, Polymer, 39(5), 1197 (1998)
  34. Rutloh M, Stumpe J, Stachanov L, Kostromin S, Shibaev V, Mol. Cryst. Liq. Cryst., 352, 149 (2000)
  35. Craig AA, Imrie CT, Macromolecules, 32(19), 6215 (1999)
  36. Craig AA, Imrie CT, Macromolecules, 28(10), 3617 (1995)