Solid-liquid interactions are determined by the surface free energy of the solid and the surface tension of the liquid applied. When the surface free energy of the solid is high, it is usually easily wetted by any liquid, such as paints. Clean, grease and particle-free, metal and glass are examples of high surface free energy materials where wetting is not an issue. In contrast, some commonly.
Confinement of cholesteric liquid crystals (ChLC) into droplets leads to a delicate interplay between elasticity, chirality, and surface energy. In this work, we rely on a combination of theory and experiments to understand the rich morphological behavior that arises from that balance. More specifically, a systematic study of micrometer-sized ChLC droplets is presented as a function of.A liquid-crystal display (LCD) is a flat-panel display or other electronically-modulated optical device that uses the light-modulating properties of liquid crystals. Liquid Crystal Displays are already widely used in consumer electronics, but research and development is still ongoing. The shifting focus of research follows a pattern of improved definition, increased display size, wider viewing.We describe a general mean field model for the free energy function for a homogeneous medium of mutually interacting molecules, based on the formalism for a biaxial nematic liquid crystal set out by Katriel et al (1986) in an influential paper in Liquid Crystals 1 and subsequently called the KKLS formalism. The free energy is expressed as the sum of an entropy term and an interaction.
A theoretical description of the process of formation of vortex flows v(t, r) and the evolution of the director field in microliter liquid crystal (LC) volumes with a free surface under the.
The free surface of a liquid just means the surface that is in contact with air. Like the horizontal surface of water in a glass. Or the top of the ocean where boats float. If you are on the topic of surface tension, then a soap bubble has two.
Liquid Crystal Hydrodynamics with Variable Order. When disclinations are present, the LC ordering becomes biaxial near the core and the order parameter drops (as represented by the background colour of the figure to the right). We have developed Finite Element discretisations of the Qian-Sheng Equations in both 2D and 3D. The Qian-Sheng equations are a generalisation of Ericksen-Leslie theory.
The free energy associated with variations of n in a sample with linear dimension R is roughly KR, but the surface free energy goes as WR 2. Remarkably, therefore, in large samples surface energy dominates, while in small samples it is the bulk energy. That’s just the opposite of what happens in systems that are not “soft.” Because liquid-crystal molecules are aspherical, external fields.
The bulk elastic energy F b scales linearly with the droplet radius R, while the surface energy F s scales as, where the coefficent W is the amplitude of the angular dependent anchoring energy from. Consequently, the energetic contribution of the interface dominates for large droplet radii. This relation might seem counterintuitive, since the ratio of surface area to bulk volume increases.
Students will observe how liquid paper can detect temperature changes. They will use this to find out that water changes state due to the gain or loss of energy. Upper elementary students will also use the liquid crystal papers to look into the transfer of heat by conduction and tie this.
By first evaluating an effective surface free-energy function characterizing the patterned substrate, we derive an expression for the effective free energy of the confined nematic liquid crystal. Then we determine phase diagrams involving a homogeneous state in which the nematic director is almost uniform and a hybrid aligned nematic state in which the orientation of the director varies.
A first principles method is proposed to calculate the Frank elastic constants of nematic liquid crystals. These include the constants corresponding to standard splay, twist and bend deformations, and an often-ignored surface-like contribution known as saddle-splay. The proposed approach is implemented on th.
By minimizing the total free energy for the system, we investigate the untwisting of the cholesteric helix as the liquid crystal attempts to align with the magnetic field. The transitions between metastable states occur as a series of pitchjumps as the helix expels quarter or half-turn twists, depending on the relative sizes of the strength of the surface potential and the bidirectional.
We call the bistabifity of ferroelectric liquid crystal (FLC) cells as the surface bistability (SB), if the dispersion part of anchoring energy is responsible for this type of bistabiity. SB was predicted theoretically (1) and investigated experimentally (2-4) .It was shown, that SB there exists in SSFLC cells possessing the bookshelf structure of smectic C layers (2) and SB there exists only.
We study spreading dynamics of nematic liquid crystal droplets within the framework of the long-wave approximation. A fourth-order nonlinear parabolic partial differential equation governing the free surface evolution is derived. The influence of elastic distortion energy and of imposed anchoring variations at the substrate are explored through.
Three Dimensional Director Modelling. The computer modelling group at UCL has many years experience in Electromagnetics, and Liquid Crystal Modelling. As a product of this work a program has been developed, which is applicable to a wide range of LC geometries. A CAD program is used to produce the mesh, supporting complex shaped volumes, and curved alignment surfaces and electrodes. A.
This suggests that the precise location of the remaining crystal habit transitions could depend not only on step free energies but also on additional factors, such as the surface mobility of premelted molecules that is embodied in the prefactor, A(T), or the diffusion limited vapor field that surrounds the crystal.
Liquid crystals (LCs) are materials in a state that has properties between those of conventional liquid and those of solid crystal. For instance, a liquid crystal may flow like a liquid, but its molecules (rod-like or disk-like) are oriented. So they have birefringent optics. When viewed under a microscope using a polarized light source, different liquid crystal phases will appear to have.