Contributions of intermicellar distance, micelle volume and screw angle to the temperature dependence of helical pitch in the intrinsic lyotropic cholesteric phases
Yükleniyor...
Tarih
2014
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Elsevier Science Bv
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Two series of lyotropic quaternary liquid crystalline mixtures exhibiting intrinsic cholesteric phases were prepared from potassium N-dodecanoyl-L-alaninate (L-KDDA) and L-serinate (L-KDDS), having different amphiphile concentrations. The phase types and texture characterizations of the cholesteric phases were determined via polarizing light microscopy. The pitches of the cholesteric phases, depending on both concentration of the L-enantiomer and temperature, were measured by laser diffraction. The helical twisting power of the cholesteric phases was calculated from the pitch values in the temperature range of 25 and 45 degrees C. The results showed that the L-KDDA system had higher helical twisting power than the L-KDDS system at all temperatures. Small-angle x-ray scattering (saxs) technique was performed for determination of some micellar level parameters, e.g. intermicellar distance (W-perpendicular to), micelle volumes (V-mic), etc, and their temperature dependences. In addition, we calculated the screw or twist angle (theta) along the helix axis of the cholesteric phases as a function of temperature, combining the saxs results with the pitch values. According to all our experimental results, it seems that theta, V-mic and W-perpendicular to contribute differently to the temperature dependence of the helical pitch. It was observed that the less (the most) contribution was provided by the intermicellar distance (the screw angle). (C) 2013 Elsevier B.V. All rights reserved.
Açıklama
Anahtar Kelimeler
Small-angle x-ray Scattering, Lyotropic Liquid Crystals, Intrinsic Cholesteric Phase, Helical Pitch, Screw Angle, Intermicellar Distance
Kaynak
Journal Of Molecular Liquids
WoS Q Değeri
Q2
Scopus Q Değeri
Q1
Cilt
191
