"Phase Transitions in Binary Mixtures of Nematic Liquid Crystal"

Abstract Experiments have been done to investigate the liquid crystalline phases and phase transitions of mixtures of 5CB and MBBA. A previous researcher prepared mixtures and developed a coexistence curve. All of her work was with untreated cells and above room temperature. The mixtures were cooled below room temperature and no additional phase transitions were observed. Surface treated cells were prepared and analyzed using video microscope techniques to investigate the alignment of the phases. It was determined that the two components are completely miscible in the nematic phase, as the formation of a uniform nematic was observed. By observing the growth of the second phase transition in a homeotropically aligned cell, the presence of an induced smectic phase was confirmed. Video microscopic techniques were also used to study the growth phenomena of the transitions. While growth was expected to follow a power law, linear growth was observed. It is suspected that the system does behave as expected, initially growing according to a power law, but then grows linearly. It was this later, linear growth that was observed. Finally, differential scanning calorimetry was used to obtain quantitative information about the transitions.

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