Çalışmada dimerik yapıda moleküllerde ve ötektik karışımlarda sıklıkla kullanılmakta olan siyanobifenil gurubuna ait 3OCB sıvı kristalinin bazı fiziksel özellikleri incelenmiştir. Bu bağlamda, farklı sıcaklık bölgelerinde optik özellikleri incelenmiştir. Optik ölçümler sonucu 3OCB’nin monotropik mezofaz sergilediği tespit edilmiştir ve söz konusu mezofazın faz aralığı belirlenmiştir. Bununla birlikte, sıvı kristalin izotropik faz-nematik mezofaz geçiş bölgesinde heterofaz alanı ortaya çıktığı gözlenmiştir. Mezofaz bölgesinin ve heterofaz alanının morfolojik analizi de gerçekleştirilmiştir. Ayrıca, kalorimetrik ölçümler gerçekleştirilerek yığın halde ilgili sıvı kristalin faz aralığının nasıl değiştiği optik ölçümlerden elde edilen sonuçlar ile kıyaslanmıştır. Kızılötesi spektroskopik ölçümler gerçekleştirilerek 3OCB’nin baskın titreşim bantları hakkında bilgiler edinilmiştir. Endüstride ve bilimsel çalışmalarda sıklıkla kullanılan 3OCB’nin kızılötesi spektroskopisi gerçekleştirilerek molekülün fonksiyonel gurupları ve yapısı hakkında bilgi edinilmesi sağlanmıştır.

Anahtar Kelimeler:

Sıvı kristaller, monotropik mezofaz, optik, DSC, FT-IR

STUDY ON PHASE TRANSITION FEATURES AND INFRARED SPECTROSCOPY OF 3OCB LIQUID CRYSTAL

In the study, some physical properties of the 3OCB liquid crystal belonging to the cyanobiphenyl group, which is frequently used in dimeric molecules and eutectic mixtures, were investigated. In this context, its optical properties in different temperature interval have been investigated. As a result of optical measurements, it was determined that 3OCB exhibited a monotropic mesophase and that the phase range of the mesophase was determined. In addition, it was observed that a heterophase region appeared in the liquid crystalline isotropic phase-nematic mesophase transition. Morphological analysis of the mesophase and heterophase region was also performed. Also, by performing calorimetric measurements, how the relevant liquid crystal phase interval changes in bulk state was compared with the results obtained from optical measurements. Information about the 3OCB's dominant vibration bands was obtained by performing infrared spectroscopic measurements. The infrared spectroscopy of 3OCB, which is frequently used in industry and scientific studies, has been performed to provide information about the functional groups and structure of the molecule.

Keywords:

Liquid crystals, monotropic mesophase, optic, DSC, FT-IR,

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