We demonstrate subnanometer resolution cryo-TEM imaging of smectic layers in the smectic and nematic phases of two bent-core liquid crystals. Our results show perfect periodicity over several hundred layers in the smectic phase and also provide the first direct evidence of smectic clusters on length scales of 30-50 nm in a nematic liquid crystal. The results are corroborated with small angle x-ray scattering measurements. The observation of smectic clusters in the nematic phase is of special interest in bent-core liquid crystals, where the smectic clusters are stable over wide temperature ranges, in contrast to the well-known pretransitional "cybotactic" clusters that appear only in the vicinity of a bulk smectic phase. The means to characterize and manipulate this nanoscale molecular order could open up completely new liquid crystal-based technologies.
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Design and Understanding of Solid-State and Crystalline Materials01/09/2015The nanostructured heliconical twist-bend nematic (Ntb) phase is a new condensed phase of matter with unique properties. Here we present the first example of an achiral hybrid bent-core liquid crystal trimer that at temperatures below the conventional N phase exhibits the Ntb phase from approximately 80 °C down through room temperature. The Ntb phase has a helical structure with a period of ~19 nm. |
Room Temperature Heliconical Twist-bend Nematic Liquid Crystal01/09/2015The nanostructured heliconical twist-bend nematic (Ntb) phase is a new condensed phase of matter with unique properties. Here we present the first example of an achiral hybrid bent-core liquid crystal trimer that at temperatures below the conventional N phase exhibits the Ntb phase from approximately 80 °C down through room temperature. The Ntb phase has a helical structure with a period of ~19 nm. |
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