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\chapter{\label{chapt:liquidcrystal}LIQUID CRYSTAL} |
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\section{\label{liquidCrystalSection:introduction}Introduction} |
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% liquid crystal |
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Long range orientational order is one of the most fundamental |
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properties of liquid crystal mesophases. This orientational |
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anisotropy of the macroscopic phases originates in the shape |
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anisotropy of the constituent molecules. Among these anisotropy |
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mesogens, rod-like (calamitic) and disk-like molecules have been |
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exploited in great detail in the last two decades. Typically, these |
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mesogens consist of a rigid aromatic core and one or more attached |
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aliphatic chains. For short chain molecules, only nematic phases, in |
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which positional order is limited or absent, can be observed, |
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because the entropy of mixing different parts of the mesogens is |
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paramount to the dispersion interaction. In contrast, formation of |
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the one dimension lamellar sematic phase in rod-like molecules with |
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sufficiently long aliphatic chains has been reported, as well as the |
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segregation phenomena in disk-like molecules. |
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% banana shaped |
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Recently, the banana-shaped or bent-core liquid crystal have became |
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one of the most active research areas in mesogenic materials and |
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supramolecular chemistry. Unlike rods and disks, the polarity and |
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biaxiality of the banana-shaped molecules allow the molecules |
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organize into a variety of novel liquid crystalline phases which |
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show interesting material properties. Of particular interest is the |
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spontaneous formation of macroscopic chiral layers from achiral |
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banana-shaped molecules, where polar molecule orientational ordering |
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is shown within the layer plane as well as the tilted arrangement of |
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the molecules relative to the polar axis. As a consequence of |
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supramolecular chirality, the spontaneous polarization arises in |
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ferroelectric (FE) and antiferroelectic (AF) switching of smectic |
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liquid crystal phases, demonstrating some promising applications in |
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second-order nonlinear optical devices. |
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The most widely investigated mesophase formed by banana-shaped |
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moleculed is the $\text{B}_2$ phase, which is also known as |
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$\text{SmCP}$. |
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%Previous Theoretical Studies |
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\section{\label{liquidCrystalSection:model}Model} |
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\section{\label{liquidCrystalSection:methods}Methods} |
