Planar degenerate substrate for micro- and nanopatterned nematic liquid-crystal cells

Abstract

Articles you may be interested inFast determination method of cell thickness and time-dependent twist angle in twisted-nematic liquid-crystal cells Rev. Sci. Instrum. 77, 043901 (2006); Induced nematic phase in a polymer/liquid crystal mixture A micro-or nanopatterned planar-aligned cell ordinarily requires a pair of mirror-image patterned substrates that must be aligned in register to Ӷ1 m. As an alternative we examine the director orientation profile of a nematic liquid crystal in a cell composed of one substrate whose easy axis is patterned on micrometer length scales and a second substrate treated for planar degenerate alignment using polymethyl methacrylate. For cell thickness Ͻ, the experimentally measured director profile in the bulk corresponds approximately to that imposed at the micropatterned substrate. The results are compared with theoretical calculations. This method provides an excellent alternative to the use of a pair of substrates aligned in close register.

Bend-Induced Melting of the Smectic-APhase: Analogy to a Type-I Superconductor

“…In the fourth quadrant a spiral easy axis pattern was scribed; this forces a weak bend distortion on the liquid crystal, which makes it easier to determine the bulk transition temperature T NA during the course of the experiment. The opposing substrate was spin coated with polymethyl methacrylate (PMMA; M w 101 000; M n 39 500), which serves as a planar degenerate alignment agent [9], such that the director is planar at the surface and the azimuthal orientation is controlled by the opposing (scribed) substrate. The two substrates were clipped together.…”

Electric field driven reconfigurable multistable topological defect patterns

“…For the cell's opposing slave substrate, a glass slide was spin-coated with the planar-degenerate alignment layer [34] polymethyl methacrylate (PMMA) and baked at 80°C for 2 h. On filling with liquid crystal, the initial alignment is isotropic planar, although a weak azimuthal memory effect develops over time. This memory effect is expected to have only a perturbative effect on the numerical simulations, which assume isotropic planar boundary conditions at the slave surface.…”

Decomposition vs. escape of topological defects in a nematic liquid crystal

“…A second ITO-coated glass substrate was cleaned and spincoated with polymethyl methacrylate (PMMA, M w = 97,000) and baked at 80°C for 120 min. The coating provides good planar-degenerate alignment surface for the liquid crystal director 15 , and serves as a "slave" surface to the patterned PVA "master" surface. The two substrates were placed together, separated by Mylar spacers, and wires were attached to the two semitransparent ITO layers, which facilitated application of an electric field across the liquid crystal sandwich.…”

“…Ackerman, Qi, and Smalyukh have used an optical technique to create 3D patterns of electrically erasable "torons", with spacings as small as [10][11][12][13][14][15][16][17][18][19][20]. Guo, et al developed a plasmonic photopatterning technique to create arbitrary patterns for planar liquid crystal alignment on length scales of tens of micrometers 4 .…”