페닐고리의 4-, 3,5-, 또는 3,4,5-위치에 아조-메소젠기를 갖는 반응성 액정화합물의 합성 및 특성 = Synthesis and Characterization of Reactive Liquid Crystalline Compounds with Azo-mesogenic Groups at the 4-, 3,5-, or 3,4,5-Positions of Phenyl Ring

국문 초록 (Abstract)

본 연구에서는 분자 내 하나의 페닐고리의 4-, 3,5-, 또는 3,4,5- 위치에 아조-메소젠기가 각각 결합된 화합물들을 합성하고 이들의 액정성 및 광화학성에 대하여 조사하였다. Azo1과 Azo2 계열의 화합물은 각각 선형과 평면형의 구조이며, Azo3 계열의 화합물은 비교적 부피가 큰 구조를 하고 있는 것으로 조사되었다. 화합물 BA-Azo2와 BA-Azo3는 액정성을 나타내지 않았고, BE-Azo1와 BE-Azo2는 단방성 액정성을, 나머지 화합물들은 양방성 액정성을 나타냈다. 이러한 액정 거동은 분자 내 아조-메소젠기의 존재로부터 부여된 것으로 액정성을 나타내는 대부분의 화합물들은 스멕틱상을 형성하였다. 그리고 모든 RM-AzoX 화합물들은 분자 내 아조기의 존재로 인하여 광 이성질현상을 나타냈으며, 광 이성질화 속도는 RM-Azo3 < RM-Azo1 < RM-Azo2의 순서로 조사되었으며, 이는 아조벤젠기 주위의 입체 장애에 의존하는 것으로 생각된다. 이러한 결과들로부터, 화합물의 액정성과 광화학적 성질들은 분자 내 페닐고리에 결합된 아조-메소젠기의 결합위치나 개수에 기인한다는 것을 알 수 있었다.

다국어 초록 (Multilingual Abstract)

In this study, compounds with azo-mesogenic groups at 4-, 3,5-, or 3,4,5-positions of one phenyl ring were synthesized, and their liquid crystallinity and photochemistry were investigated. The compounds in the Azo1 and Azo2 series had linear and planar geometries, respectively, while those in the Azo3 series had relatively bulky structures. Compounds of BA-Azo2 and BA-Azo3 did not show any liquid crystallinity. Compounds of BE-Azo1 and BE-Azo2 exhibited a monotropic liquid crystallinity, while the other compounds showed an enantiotropic liquid crystallinity. The liquid crystalline behavior was imparted by the azo-mesogenic groups, and most of the liquid crystalline compounds formed a smectic phase. All the RM-AzoX compounds exhibited photoisomerism because of the presence of the azo groups in the molecule. The rate of photoisomerization followed the order of RM-Azo3 < RM-Azo1 < RM-Azo2 and was considered to depend on the steric hindrance around the azobenzene groups in the molecule. These results suggest that the liquid crystallinity and photochemical property of the compounds are affected by the position or the number of azo-mesogenic groups phenyl ring of the molecule.

참고문헌 (Reference)

1 권영완, "액정성 전방향족 폴리에스테르" 한국고분자학회 29 (29): 523-535, 2005

2 김형준, "아조벤젠 분자의 사슬 내 위치에 따른 고분자 블렌드 박막의 비등방성 광 변형에 관한 연구" 한국공업화학회 23 (23): 65-70, 2012

3 김대윤, "광감성 카이랄 아조벤젠 액정의 합성 및 분석" 전북대학교 대학원 2012

4 I. Dierking, "Texture of Liquid Crystals" Wiley-VCH 2006

5 R. Mohan Kumar, "Synthesis, characterization and photolysis studies on liquid crystalline poly[4-(4’-x-biphenyl)yl-4”-(m-methacryloyloxyalkyloxy)cinnamate]’s" 43 : 2648-2659, 2007

6 M. R. Karim, "Synthesis of polymerizable liquid crystalline monomers and their side chain liquid crystalline polymers bearing azo-ester linked benzothiazole mesogen" 293 : 1923-1935, 2015

7 E. Merino, "Synthesis of azobenzenes : The coloured pieces of molecular materials" 40 : 3835-3853, 2011

8 F. Kuschel, "Study of the micro-phase separation in LC-polymers with paired mesogens" 23 : 373-379, 1993

9 M. J. Lee, "Silicon-containing azo polymers with paired mesogens and their applications to optical memory media" 46 : 6734-6745, 2008

10 W. L. F. Armarego, "Purification of Laboratory Chemicals" Elsevier Science 2003

11 J. Horvàth, "Polymerization in liquid crystal-XVII. Effect of flexible substituents in the mesogenic side-chain on the behaviour of mesogenic polymers" 21 : 251-257, 1985

12 H. Thiem, "Photopolymerization of reactive mesogens" 206 : 2153-2159, 2005

13 N. Tamaoki, "Photochemical phase transition and molecular realignment of glass-forming liquid crystals containing cholesterol/azobenzene dimesogenic compounds" 15 : 719-726, 2003

14 N. Tamaoki, "Photochemical phase transition and molecular realignment of glass-forming liquid crystals containing cholesterol/azobenzene dimesogenic compounds" 15 : 719-726, 2003

15 A. V. Bogdanov, "Photo-orientation of azobenzene-containing liquid-crystalline materials by means of domain structure rearrangement" 117 : 13936-13945, 2013

16 C. J. Barrett, "Photo-mechanical effects in azobenzene-containing soft materials" 3 : 1205-1320, 2007

17 D. Y. Kim, "Main chain liquid crystalline polymers" 2 : 415-423, 1991

18 H. Finkelmann, "Liquid crystalline polymers with biphenyl‐moieties as mesogenic group" 179 : 2541-2544, 1978

19 S. Alazaroaie, "Liquid crystalline polymers 14. Synthesis and thermal behaviour of some polyethers containing azo-mesogens" 39 : 1333-1339, 2003

20 N. Hosono, "Large-area three-dimensional molecular ordering of a polymer brush by one-step processing" 330 : 808-811, 2010

21 T. Kumagai, "Dielectric properties of dual-frequency reactive mesogens before and after photopolymerization" 7 : 1113-1121, 2014

22 B. Reck, "Combined liquid-crystalline polymers : Rigid rod and semi-flexible main chain polyesters with lateral mesogenic groups" 7 : 389-396, 1986

23 R. Zentel, "Combined LC main chain/side chain polymers" 47 : 141-149, 1996

24 T. Kreouzis, "Chapter 5. Charge transport in reactive mesogens and liquid crystal polymer networks" Springer 2013