研究目的
Investigating the phase transitions in nano?lms of polar smectic liquid crystals with multilayer periodicity and their dependence on film thickness and temperature.
研究成果
The number of phases forming in the ?lms increases with increasing the number of molecular layers. Two types of transformation of structure and polarization of the ?lms were observed. The combination of experimental data and calculation results enabled to propose possible structure of phases in the ?lms. The used model is suitable to describe the transition between commensurate structures in bulk sample as well as sequence of transitions in thin ?lms.
研究不足
The study is limited to freestanding nano?lms with a thickness from 2 to 6 molecular layers. The high-temperature SmC?α phase in bulk samples is not described by the planar model used in calculations.
1：Experimental Design and Method Selection:
Optical investigations and calculations of structures were performed on freestanding nano?lms of liquid crystal with a sequence of phase transitions. The methodology included polarized and depolarized microscopy to study nano?lms in a wide temperature range.
2：Sample Selection and Data Sources:
Freestanding nano?lms with the number of smectic layers from 2 to 6 were investigated. The number of molecular layers in the film was determined with absolute precision from optical reflectivity measurements.
3：List of Experimental Equipment and Materials:
Homemade electrooptical cells, Olympus BX51 optical microscope equipped by CCD receivers, spectrometer, and digital video cameras were used. The liquid crystal used was (R)-12OF1M
4：Experimental Procedures and Operational Workflow:
Films were prepared by drawing the liquid crystal across an opening by a thin spatula. Measurements were conducted with the aid of optical microscopy, capturing images of the film, and spectral measurements.
5：Data Analysis Methods:
The structures and phase transitions were calculated in the framework of Landau theory of phase transitions with two-component order parameter.
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