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Molecular aggregation in liquid-crystalline layers crucially affects their physics: smectic A (SmA)–nematic (N) phase transition
Autorzy
Rok wydania
2023
Czasopismo
Numer woluminu
19
Strony
7245-7254
DOI
10.1039/d3sm00958k
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
Recently, two molecular packing modes of the alkyl chain in smectic A (SmA) liquid crystal phases were revealed: normal and tilted types, which are named by the orientation relative to the layer normal. This study reveals the relationship between the packing mode and thermodynamic order of the SmA–nematic (N) phase transition. Two normal type and three tilted type mesogens were subject to thermodynamic and structural experiments. The DSC results showed that the SmA–N phase transitions of the normal and tilted types are of the second and first order, respectively. The analysis of the intensities of reflections in wide-angle X-ray diffraction related to the periodicity of the SmA layer yielded the distribution of the mass centers of molecules along the normal to the SmA layers. The resultant distribution offered a rationale for the correlation of the thermodynamic order of the SmA–N phase transition and molecular packing modes in the SmA phases based on the Meyer–Lubensky theory.
Adres publiczny
http://dx.doi.org/10.1039/d3sm00958k