By Giovanni Barbero, Luiz Roberto Evangelista

Regardless of the big volume of phenomenological details about the bulk houses of nematic section liquid crystals, little is known concerning the beginning of the skin strength, relatively the skin, interfacial, and anchoring houses of liquid crystals that have an effect on the functionality of liquid crystal units. Self-contained and particular, Adsorption Phenomena and Anchoring strength in Nematic Liquid Crystals presents an account of recent and verified effects spanning 3 many years of study into the issues of anchoring power and adsorption phenomena in liquid crystals. The ebook includes a targeted dialogue of the starting place and attainable resources of anchoring power in nematic liquid crystals, emphasizing the dielectric contribution to the anchoring strength particularly. starting with basic floor and anchoring homes of liquid crystals and the definition of the nematic section, the authors clarify how selective ion adsorption, dielectric strength density, thickness dependence, and bias voltage dependence impression the uniform alignment of liquid crystals and impact the functionality of liquid crystal units. additionally they speak about basic equations regulating the adsorption phenomenon and the dynamic points of ion adsorption phenomenon in liquid crystalline platforms. Adsorption Phenomena and Anchoring strength in Nematic Liquid Crystals serves as a great resource of reference for graduates and researchers operating in liquid crystals, complicated fluids, condensed topic physics, statistical physics, chemical engineering, and digital engineering, in addition to offering an invaluable normal creation to and historical past info at the nematic liquid crystal section.

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Extra resources for Adsorption phenomena and anchoring energy in nematic liquid crystals

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1 Stochastic contribution to the anchoring energy The effect of a stochastic contribution to the surface energy, coming from the direct interaction between an orienting film and a solid substrate, indicates that, in the hypothesis in which the NLC orientation coincides with the film orientation, the Rapini-Papoular expression for the anisotropic part of the surface energy has to be modified. There are two important modifications: (1) the first one is a renormalization of the anchoring strength coefficient, connected with the square of the sine of the deformation angle; (2) the second one is the presence of an additional contribution, proportional to the fourth power of the same quantity.

44) where σ is the surface density of the molecules of the film. This assumption is equivalent to stating that long range electrostatic contributions in the interaction energy between the molecules of the film can be neglected. 45) where |δm| 1. This hypothesis means that m is considered a macroscopic quantity and hence changes over macroscopic distances d ρ. Only in this case it is possible to build an elastic theory for the orienting film. 47) δm=0 and g(m, m, r) is the uniform part of the interaction energy.

The NLC distortion is supposed planar in the (x, z) plane. The average NLC orientation is described by means of the tilt angle θ = arccos(n · k). For the sake of simplicity, θ = θ(z) only. 90) VN where J(r) = −C/r6 , with C being a positive constant, and VN the effective interaction volume. 91) Am where e is the eccentricity of the ellipsoidal interaction volume and it is supposed to be equal to the one of the NLC molecule. Furthermore, Am and AM are, respectively, the z coordinate of the lowest and highest point of the ellipsoid, and ∆ F0 = F0b − F0 (z), where F0b is the bulk value of the uniform part of the free energy density.

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