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Is the nematic to isotropic phase transition reversible?
A shape change in length of 90% parallel to the alignment direction was obtained during the nematic–isotropic phase transition [16]. A reversible actuation of an LCP film can lift up and put down a 10 g weight when heating and cooling (Figure 3a) [56].
What is isotropic phase?
A true liquid is isotropic , meaning that its properties are uniform in all directions— the result of its molecules being in constant random motion. Crystalline solids, in contrast, are anisotropic ; optical- and other properties such as thermal and electrical conductivity vary with direction.
What is difference between nematic vs smectic phase?
In the nematic phase, the molecules are not layered but are pointed in the same direction. As a result, the molecules are free to rotate or slide past one another. In the smectic phase, the long axes of the molecules are parallel, and the molecules are also arranged in planes.
What is smectic and nematic?
The key difference between nematic smectic and cholesteric liquid crystals is their structure. Nematic liquid crystals have no ordered structure of molecules, and smectic liquid crystals have a layered molecular structure, whereas cholesteric liquid crystals have the molecules in a twisted and chiral arrangement.
What is Landau theory of phase transition?
The Landau theory of phase transitions is based on the idea that the free energy can be expanded as a power series in the order parameter m. The parameters that are input into the form are also used to plot the temperature dependence of the order parameter, the free energy, the entropy, and the specific heat.
What liquid is in LCD?
The basis of LCD technology is the liquid crystal, a substance made of complicated molecules. Like water, liquid crystals are solid at low temperatures. Also like water, they melt as you heat them. But when ice melts, it changes into a clear, easily flowing liquid.
What are the three types of liquid crystals?
There are three types of thermotropic liquid crystals: discotic, conic (bowlic), and rod-shaped molecules.
What is a smectic phase?
: of, relating to, or being the phase of a liquid crystal characterized by arrangement of molecules in layers with the long molecular axes in a given layer being parallel to one another and those of other layers and perpendicular or slightly inclined to the plane of the layer — compare cholesteric, nematic.