Applied Chemistry for Engineering (공업화학)

The Korean Society of Industrial and Engineering Chemistry (한국공업화학회)
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Synthesis and Properties of Unsymmetric Dimesogenic Liquid Crystal Compounds Containing Lateral Substituent

측면에 치환기를 포함하고 있는 비대칭 이메소젠 액정화합물의 합성 및 성질

  • Park, Jong-Ryul (Division of Advanced Materials Science and Engineering, Kongju National University) ;
  • Cho, Kuk Young (Division of Advanced Materials Science and Engineering, Kongju National University) ;
  • Bang, Moon-Soo (Division of Advanced Materials Science and Engineering, Kongju National University)
  • 박종률 (공주대학교 신소재공학부) ;
  • 조국영 (공주대학교 신소재공학부) ;
  • 방문수 (공주대학교 신소재공학부)
  • Received : 2015.02.28
  • Accepted : 2015.04.08
  • Published : 2015.06.10
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Abstract

Two series of unsymmetric dimesogenic compounds containing a butylene or pentamethylene group as the flexible spacer were synthesized and their thermal and mesomorphic properties were studied. Mesogenic groups of the synthesized compounds consisted of a cholesteryl and an azobenzene group with lateral substituent. Chemical structures and mesomorphic properties of the synthesized compounds were investigated by FT-IR, $^1H$-NMR, differential scanning calorimeter (DSC), and polarizing optical microscope (POM). All synthesized compounds, apart from $D5-OCH_3$, showed enantiotropic liquid crystal phases. Compounds having an even number of carbon atoms in the flexible spacer exhibited wide mesophase temperature ranges and high isotropic transition temperatures. Regarding the effect of lateral substituents, compounds with bulky substituents exhibited decreased mesophase temperature ranges and isotropic transition temperatures, while those with polar substituents showed the increased thermal stability of the smectic phase.

유연격자로서 분자 중앙에 부틸렌 또는 펜타메틸렌기를 갖는 두 시리즈의 비대칭 이메소젠 화합물을 합성하고, 이들의 열적성질 및 액정성을 연구하였다. 합성된 화합물의 메소젠기는 콜레스테릴기와 곁 치환기를 포함하고 있는 아조벤젠기로 되어 있으며, 이들 액정화합물의 화학구조와 액정성은 FT-IR, $^1H$-NMR, 시차주사열량분석기(DSC), 편광현미경(POM)에 의하여 조사되었다. 화합물 $D5-OCH_3$를 제외한, 합성된 모든 화합물들은 양방성 액정성을 나타내었고, 유연격자의 탄소수가 짝수인 경우 넓은 액정상 온도구간과 높은 등방성 전이온도를 나타내었다. 곁 치환기가 액정성에 미치는 영향으로, 부피가 큰 치환기를 갖는 화합물들은 좁은 액정상 온도구간과 낮은 등방성 전이온도를 나타내었으며, 극성 치환기를 갖는 화합물들은 스멕틱 액정상의 높은 안정성을 나타내었다.

Keywords

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