Adsorption phenomena and anchoring energy in nematic liquid by Giovanni Barbero, Luiz Roberto Evangelista

By Giovanni Barbero, Luiz Roberto Evangelista

Regardless of the big volume of phenomenological info in regards to the bulk houses of nematic part liquid crystals, little is known in regards to the starting place of the skin strength, rather the skin, interfacial, and anchoring houses of liquid crystals that impact the functionality of liquid crystal units. Self-contained and special, Adsorption Phenomena and Anchoring power in Nematic Liquid Crystals presents an account of recent and tested effects spanning 3 a long time of study into the issues of anchoring strength and adsorption phenomena in liquid crystals. The ebook incorporates a particular dialogue of the starting place and attainable assets of anchoring strength in nematic liquid crystals, emphasizing the dielectric contribution to the anchoring strength particularly. starting with primary floor and anchoring houses of liquid crystals and the definition of the nematic section, the authors clarify how selective ion adsorption, dielectric power density, thickness dependence, and bias voltage dependence effect the uniform alignment of liquid crystals and have an effect on the functionality of liquid crystal units. additionally they speak about basic equations regulating the adsorption phenomenon and the dynamic facets of ion adsorption phenomenon in liquid crystalline structures. Adsorption Phenomena and Anchoring strength in Nematic Liquid Crystals serves as a very good resource of reference for graduates and researchers operating in liquid crystals, advanced fluids, condensed topic physics, statistical physics, chemical engineering, and digital engineering, in addition to delivering an invaluable basic creation to and heritage info at the nematic liquid crystal part.

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If n is always parallel to the (x, z) plane, φ = 0 and Eq. 74) where K(θ) = K11 sin2 θ + K33 cos2 θ. , no twist is considered. , θ = π/2, Eq. 75) K22 φ , 2 which is relevant to a pure twist deformation. Finally, the one-constant approximation (K11 = K22 = K33 = K) is commonly employed and, in this case, Eq. 73) is written as f (φ, φ ) = f (θ, θ , φ, φ ) = Copyright © 2006 Taylor & Francis Group, LLC 1 2 2 K θ + sin2 θ φ . 77) where fS (θ, φ) takes into account the surface contribution to the total energy and will be considered in detail in the next chapter.

F0 (m) is the surface energy density of a uniformly oriented film (m position independent), whereas L, N , and M play the role of elastic constants. Tensors L, N , and M have to be decomposed in terms of the elements of symmetry of the film. In the present case, in which the film is assumed to be flat, the elements of symmetry are the geometrical normal k (parallel to the z−axis) and the vector m (see details in [29]). The term f0 (m) can be expanded in power series of m · k, or in terms of Legendre polynomials.

8) This simplified expression permits a simple interpretation for the surface free energy. In this case WP is the anchoring energy which, as defined before, corresponds to the work that has to be done to rotate the director from the stable equilibrium position to the unstable one. In general, it is possible to start with the Rapini-Papoular expression by operating in the following manner. 9) fs = − W (n · n0 )2 , 2 in such a manner to underline the fact that the easy direction is the one which, in the absence of external torques, minimizes the surface free energy.

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