Molecular Frustration of Chemically Linked Rod-Disc Liquid Crystal under an Electric Field

Abstract

Molecular orientation of a chemically linked rod-disk (cyanobiphenyl-triphenyl) liquid crystalline (LC) molecule (RD12, where 12 is a number of carbon atoms in each alkyl chain linkage between the rod and the disk mesogens) in an antiparallel rubbed LC cell was investigated under vertically applied alternative current (AC) electric fields. Upon varying vertical AC electric fields from the initial state (0 V) to a fixed voltage ranging between 2.5 and 5.0 V, it was found that RD12 responded to the electric field with two-steps. The rod mesogen having a higher dipole interaction first aligned parallel to the electric field, while the disk mesogen behaved like an anchor of RD12. After the frustration and stabilization of rod mesogens, the in-plane axis of disk mesogen also aligned parallel to the electric field. Based on our experimental results, it was concluded that the peculiar molecular frustrations of RD12 under the vertical AC electric field occurred in a consequence of the competition among rods attached to both sides of the disk molecule. Furthermore, because molecular orientation of RD12 exhibiting a large birefringence is controlled by an electric field, RD12 can be used as a tunable optical switching material in the electro-optical devices.

Polymer‐Stabilized Chromonic Liquid‐Crystalline Polarizer

“…It is obvious that the uniaxial orientation of H‐SY molecule in the LC phase is retained during the photo‐polymerization and the developing processes. Patterned polarizers fabricated by a simple coating and photo‐polymerization may pave new pathways for the applications of LCLC to electro‐optic devices, especially for the optical devices requiring polarized light in a local area 51–53…”

Adding Symmetry: Cylindrically Confined Crystallization of Nylon-6

“…The polymer nanostructure of one-, two-, or three-dimensional (1D, 2D, or 3D) confinement has been investigated in both block copolymers and homopolymers. − Previous observation shows that the fast crystal growth orientation of a polymer depends on the geometry of the constrained space. − The 2D-confined polymer crystallization has been studied through phase separation of the block copolymer, electrospun fiber coated with a glassy polymer, or by using a nanoporous aluminum template. ,,− …”

Suppressed Crystallization of Rod-Disc Molecule by Surface Anchoring Confinement

“…Surprisingly, RD12 responded to the electric field with a two-step process in the vertical electric field LC cell. After frustration and stabilization of the rod mesogens, the whole RD12 molecule was aligned parallel to the vertically applied electric field . It was also found that the molecular frustrations of RD12 under the vertical AC electric field as a result of the competition between the rod mesogens attached to both sides of the disc mesogen.…”

“…From this perspective, we have reported the characteristics of the rod-disc molecule (RD12), which was newly synthesized by the chemical combination of rodlike (R) and disclike (D) mesogens. − The chemical structure of RD12 is illustrated in Figure . Through combined experimental results and careful analyses, it was realized that the RD12 molecule can form three different ordered phases by decreasing the temperature from the isotropic (I) phase: N phase, stable K T1 crystalline phase, and metastable K T2 crystalline phase. − Utilizing the two-dimensional X-ray diffraction technique, the biaxial N molecular arrangement of RD12 was demonstrated under a direct current (DC) electric field. − Upon varying the alternating current (AC) electric fields, molecular orientation of RD12 was systematically investigated in the vertical as well as in-plane electric fields . Surprisingly, RD12 responded to the electric field with a two-step process in the vertical electric field LC cell.…”