Hirotsugu Kikuchi 교수

A polymer-stabilized liquid-crystal blue phase with a Kerr constant 170 times larger than that of nitrobenzene is shown to be capable of microsecond electro-optical switching over a wide temperature range in flat Kerr cells, without need for additional surface processing to generate alignment. The Figure shows a polarizing optical micrograph, under crossed polarizers, of an in-plane switched Kerr cell containing the polymer-stabilized blue phase.

An anomalously large dielectric permittivity of ≈10⁴ is found in the mesophase temperature range (MP phase) wherein high fluidity is observed for a liquid-crystal compound having a 1,3-dioxane unit in the mesogenic core (DIO). In this temperature range, no sharp X-ray diffraction peak is observed at both small and wide Bragg angles, similar to that for a nematic phase; however, an inhomogeneous sandy texture or broken Schlieren one is observed via polarizing optical microscopy, unlike

The magnitude of local stress applied to a polymer surface in the buffing process, which is a critical method to uniformly align liquid crystals for displays, has been evaluated from the polarizing optical microscopic investigation of nematic liquid crystals in contact with polyimide surfaces which were suitably buffed in order to visualize the individual tracks of the buffing rayon fibers. The estimated magnitude of local stress is most likely to be far greater than the yield stress of the poly

Abstract Blue phases have two major advantages over commonly used nematic phases:1) the response is much faster, 2) the zero‐electric field state is optically isotropic. We demonstrate the sufficiently large electric field‐induced birefringence and the micro‐second response of the polymer‐stabilized blue phases and the induced‐isotropic phases without any surface treatment.

Ferroelectricity in fluid materials, which allows free rotation of molecules, is an unusual phenomenon raising cutting-edge questions in science. Conventional ferroelectric liquid crystals have been found in phases with low symmetry that permit the presence of spontaneous polarization. Recently, the discovery of ferroelectricity with high symmetry in the nematic phase has attracted considerable attention. However, the physical mechanism and molecular origin of ferroelectricity are poorly underst

The relationship between the electrooptic response properties and the chiral pitch of a blue phase was experimentally investigated. The Kerr constant was found to be proportional to the cube of the chiral pitch, although a theoretical square-law was expected. It was also revealed that the effect of the chiral pitch on the response time was dependent on the type of electric field-induced birefringence of the blue phase, such as local director reorientation and electrostriction. The response of th

Abstract In this paper, we present the phase behavior and electro‐optical Kerr effect of the optically isotropic liquid crystal composites, which require no surface treatment for device fabrication. Anomalously large Kerr constant, more than 10 −8 mV −2 and fast response, less than sub‐milli‐second were observed at a room temperature.

Ultrasmall-angle synchrotron X-ray scattering measurements showed that a three-dimensional polymer lattice of a few 100 nm order with body-centered cubic O(8-) symmetry was formed in a polymer-stabilized blue phase liquid crystal. We obtained clear experimental evidence that the polymer chains condensed selectively in the disclinations within the blue phase during photo-polymerization of monomers in the blue phase.

Abstract Liquid crystalline blue phases (BPs) show excellent potential for application in tunable photonic devices because they possess the unique optical property that the selective 3D Bragg diffraction in a visible wavelength region can be continuously shifted using an electric field. A new approach to simultaneously extend the wavelength range of field‐induced Bragg diffraction shift and the temperature range of thermodynamically stable BPs is critically needed. Here, a new BP material system

The widespread electro-optical applications of polymer dispersed liquid crystals (PDLCs) are hampered by their high-driving voltage. Attempts to fabricate PDLC devices with low driving voltage sacrifice other desirable features of PDLCs. There is thus a clear need to develop a method to reduce the driving voltage without diminishing other revolutionary features of PDLCs. Herein, we report a low-voltage driven PDLC system achieved through an elegantly simple and uniquely designed acrylate monomer

The introduction of electron-withdrawing groups such as CN and NO 2 groups at the end position of C3-DIO analogues increases the dipole moments above 8.5 D, which is effective method for the emergence of ferroelectric nematic phases in C3-DIO series.

Abstract A series of thin films composed of liquid crystalline polymer (LCP) and low molecular weight liquid crystal (LMWLC) was prepared by a solvent‐casting method. LMWLC is miscible over a whole range of LCP concentrations in isotropic and mesomorphic states. The composite system formed a smectic phase in a LCP weight fraction range above 50%. Reversible and bistable electro‐optical effects based on light scattering were recognized for a smectic phase of the binary composite composed of LCP a

Abstract Mechanical stretching characteristics of a single polystyrene chain in a dilute solution was investigated with atomic force microscope. An entropic elasticity expressed by the extended Langevin function was observed in a force range below 200 pN and an extension range below 60 nm.