The Role of Host Molecules in the Crystalline Inclusion Compounds: Hexamethylenebis(trimethylammonium) dications as guest species

ABSTRACT

This report demonstrates hybrid homeotropic alignment of liquid crystals (LCs) using a self-assembled molecular (SAM) layer. 4-(4-Hep-tylphenyl)benzoic acid forms a SAM layer through hydrogen bonding with indium-tin oxide (ITO) substrate, and the LCs were aligned vertically without a polyimide (PI) layer on one side of substrate. The proposed hybrid structure featured a more stable homeotropic alignment than the LC device (LCD) with only half of a PI layer, and showed electro-optical characteristics similar to conventional LCDs with full PI layers. The SAM layer showed stable alignment and fast response in the LC cell by a simple doping method.     

Fabrication of a fast-switching liquid crystal device using reactive self-assembled polyimide alignment layer

ABSTRACT

We proposed a new vertical alignment method for simultaneously improving the alignment force and electro-optical properties. The key point of the new method is the self-assembly of the reactive monomer via hydrogen bonding with the polyimide alignment layer and the formation of pre-tilt using the reactive monomer on an alignment layer. Through the self-assembly of the reactive monomer and the generation of the pre-tilt, it is possible to obtain a higher alignment force and a fast response time. As a result, through a simple additional step, we can fabricate a fast-switching liquid crystal device using a reactive self-assembled alignment layer.     

Glass Dispersed Liquid Crystals

Abstract

Liquid crystals can be trapped into inorganic (silica) substrates by sol-gel processes. The sol-gel process consists of hydrolysis and polycondensation reactions of metal organic monomers, i.e. organoalkoxy silanes, which allows the formation of a silica gel-glass. These processes have been used since 1984 for trapping organic molecules into inorganic oxides; usually, single molecules are trapped into isolated gel-glass (nm size) pores. However, it is possible, by chemical means, to induce larger (0.1–10 pm) cavities in the network of the gel-glass allowing the formation of embedded micron size droplets of low molecular weight nematic LC molecules. Surface variations in these cavities (e.g., providing a molecular oriented surface using Si-CH,CH, groups on the pore cage) may allow a lamellar structure and alignment of the nematogenic LC compounds at the surface. It was suggested that order arises as a consequence of the chemical affinity between the apolar character of the pore surface and the lipophilic groups of the LC. Therefore, the main concern has been to ascertain whether the sample manufacturing keeps the LC structure, thus giving gel-glass dispersed liquid crystals (GDLCs) with electrooptical response.     

A fast-switching vertically-aligned liquid crystal device based on a multi-functional mesogenic photocrosslinker

Abstract

A vertically-aligned liquid crystal (LC) device with fast-switching LC molecules and excellent electro-optical properties is proposed. The proposed method employs a mixture of a polyimide to achieve the desired vertical alignment, and a mesogenic photocrosslinker to obtain the fast LC response. More specifically, the photocrosslinkers were photopolymerized by UV irradiation under an electric field to pre-tilt the LC molecules. In addition, upon increasing the number of functional groups in the photocrosslinker, faster switching properties were exhibited due to enhanced pre-tilting. Following UV irradiation, the proposed system also exhibited stable homeotropic alignment properties similar to those of conventional polyimides.     

Company News

Abstract

Rolic Ltd, a recently launched liquid crystal R&D company from Roche, has announced the development of several new path-forging technologies which are expected to have a major impact on the liquid crystal display (LCD) and copy-proof security industries in the future. Rolic's inventions solve many of the challenges facing the LCD industry, such as view angle dependency, high cost and response time. They represent a quantum leap in making high resolution, large area displays possible. Rolic will make essential contributions to the development of refined, ultra high resolution image and display products. Rolic's future products will enable visual computing professionals as well as the general public to work more effectively with a greater variety of new-age information displays than ever before.     

Liquid Crystal Alignment Behaviors of Polystyrene Derivatives Containing Coumarin Moieties

We synthesized a series of polystyrene derivatives containing coumarin side groups, poly(7-(4-vinylbenzyloxy)coumarin) (P7COU#) and poly(7-(4-vinylbenzyloxy)4-phenylcoumarin) (P7COU4P#), where # is the molar content of 7-hydroxycoumarin and 7-hydroxy-4-phenyl coumarin, respectively, using polymer analogous reaction, in order to study the effect of the 7-hydroxycoumarin and 7-hydroxy-4-phenyl coumarin side groups on the liquid crystal (LC) alignment properties. The LC alignment behavior of these two series was investigated by photoalignment or rubbing alignment. The LC cells made from photoirradiated P7COU# and P7COU4P# films showed homogeneous planar LC alignment. We found that LC aligning ability of the LC cells made from rubbed P7COU# and P7COU4P# films were affected by the structure and molar content of coumarin side groups. For example, anchoring energy of the LC cell fabricated with rubbed P7COU82 (7 × 10^?5 J/m²) and P7COU4P81 (7 × 10^?7 J/m²) film was increased drastically and slightly compared to polystyrene (10^?7?10^?8 J/m²), respectively. Particularly, anchoring energy of the LC cell made from rubbed P7COU# having more than 51 mol % of the 7-hydroxycoumarin as a side groups is comparable to that of the conventional polyimide in the LCD industry.     

Synthesis,structure, and mesomorphism of novel liquid crystalline acrylate monomers and polymers

A series of novel liquid crystalline monomers (M₁?M₈) and side chain polymers base polyacrylate backbone were synthesized. The chemical structures were characterized by FT-IR and ¹H-NMR spectra. The mesomorphism and thermal behavior was investigated by polarizing optical microscopy, differential scanning calorimetry, and thermogravimetric analysis. The relationships of structure and mesomorphism are discussed in detail. The eight monomers and their corresponding polymers all show enantiotropic nematic phase. With increasing the spacer length or flexibility of the terminal group, the melting temperature (T_m) and isotropic temperature (T_i) of the corresponding monomers and polymers all decreased. However, with increasing the rigidity of the mesogenic core, T_m and T_i of the corresponding monomers and polymers all increased. TGA showed that all the polymers obtained in this study had excellent thermal stability.     

Design,Synthesis and Physical Properties of New Liquid Crystal Materials for Active Matrix LCD (1)

Abstract

Liquid crystal materials having a decahydronaphthalene ring structure were designed for active matrix LCD and were prepared by hydrogenation of the ocatahydronaphthalenes obtained through the reaction of a fluorinated phenyl magnesium bromide with the 6-alkyl-decahydronaphthalen-2-ones and followed by dehydration. These compounds exhibit wide nematic temperature ranges with low melting points and very low birefringences. These results are useful for design of new liquid crystal mixtures for TFT-displays.     

The fiftieth anniversary of the liquid crystal display

ABSTRACT

A record is given of the special meeting organised by the UK&I Chapter of the Society of Information Display held at the Royal Academy of Engineering in London, to celebrate the 50th anniversary of the RCA announcement of the first Liquid Crystal Display on 28th May 1968. Coming exactly eighty years after the report of the first liquid crystal materials, this announcement sparked interest across the globe, and particularly in the UK, Switzerland and Japan. Presentations of the early LCD history from Hilsum, Schadt and Raynes give insights into both the science and also the process of invention itself. These early contributors are followed by a view from the USA from Bos and representation from the companies Sharp and Merck that helped shape the success of these fascinating and useful materials. Also reviewed are talks on the use of organic semiconductors to drive plastic LCD by Sirringhaus, reflective LCD of Folium Optics, retail signage of Displaydata, as well as a look to the future from LCD competitors from Bodle (Phase Change Material displays) and BOE (OLED).     

Structure,Stability and Response to the Electric Field of Antiferroelectric Smectic Materials

Abstract

The structure and switching of five antiferroelectric mesogens are studied by the constant temperature-pressure molecular dynamics simulation. The conformations of the end chains in the smectic phase are compared with those at an isolated single molecule estimated by the method of molecular orbitals, where the bending angle of the chiral chain as well as the angle of the achiral one is shown to be enhanced. The tilt angles obtained here are in well agreement with the experimental ones. The response of the anticlinic alignment to the transverse electric field is also tested.     

Stanford Resources Market Analysis for LCD Industry 1997

Abstract

The latest report from Stanford Resources on the LCD industry provides a forecast of the world-wide market for LCD materials and equipment based on the demand for supeWisted-nematic (STN) LCDs and TFT-LCDs through the year 2003. The publication LCD Manufacturing Materials and Equipment 7997 predicts strong growth in a number of market sectors. The demand for glass substrates will total nearly $1.3 billion in 2003. Currently the market for TN-LCD and STN-LCD glass substrates is twice the size of the TFT-LCD glass substrate market, however this will change dramatically as prices decline in the TFT-LCD market, allowing for strong growth in demand for notebook computers and desktop monitors.     

The world's largest LCD production facility nears completion in Japan

Abstract

Sharp Corporation is constructing the world's largest-scale dedicated manufacturing facility for LCD panels in Taki-cho. Taki County, Mie Prefecture. Located between Osaka and Nagoya Cities this region is known worldwide for its fine cultured pearls. The breadth of equipment and devices using advanced liquid-crystal display panels will grow tremendously in coming years, and this new plant is designed to meet the expected increase in demand.     

Sharp develops the world's largest 40 inch colour TFT LCD

Abstract

The supeplarge direct-viewing colour TFT LCD created with Sharp's advanced larger mother glass and seamless joint technologies     

Photochemical activities of polymers with aurone fragment

ABSTRACT

In this work we report preliminary results obtained for methacrylic polymers incorporating aurone side-group as photochemical active molecule. The aurone polymers were obtained by a three-step synthetic approach: (2Z)-6-hydroxy-2-(4-R-benzyliden)-1-benzofuran-3(2H)-ones were synthesized by using condensation reation of 6-hydroxybenzofuran-3-one with benzaldehydes; then methacrylate monomers were synthesized by reaction the alcohols with methacryloyl chloride; and the polymers were synthesized by free radical polymerization. Polymers were characterized by ¹HNMR spectroscopy and DSC techniques. Their physicochemical properties are determined by absorption, fluorescence excitation and emission spectroscopies.     

Dielectric monitoring of curing process for some epoxide-amine thermosets

Three recently synthesized epoxy monomers were studied. All the monomers form a nematic phase in temperatures above 80 °C. This paper presents the dielectric response of pure monomers in the frequency range of 10⁶–10⁹ Hz as well as its changes occurring in the course of crosslinking with 4,4′-diaminodiphenylmethane used as curing agent. A relaxation process related to molecular motions is clearly visible in this frequency range for each of the monomers, though its characteristics are somewhat different in particular cases. The evolution of the relaxation process is visible in the course of curing. The dynamics of curing observed through dielectric data is compared with the results of differential scanning calorimetry measurements.     

Solid State Behaviour of Vinyl Quinones

Abstract

2,5-Bisvinyl-1,4-benzoquinones 1 and 2-vinyl-1,4-bsnzoquinones 2 substituted with aryl or ester end groups have been synthesized. The 2,5-bisstyryl-1,4-benzoquinones 1 (R=phenyl, p-tolyl, o-tolyl) crystallize with a 7 Å-stacking axis. But only for the o-tolyl derivative the contacts between the vinyl groups are close enough to allow a four-center type photopolymerization. The ester derivative 1 (R=COOEt) has a layer structure and can be photooligomerized in the crystal. The generated cyclobutane subgroups have twofold symmetry. The vinylquinones 2 (R=aryl) may be dimerized photochemically in the crystal at the vinyl groups to centrosymmetric cyclobutanes. Crystals with 4 Å stacking axis are also photoreactive.     

Conference Reports

Abstract

The 1995 Society for Information Display (90) International Symposium is the premier international gathering of scientists, engineers, technologists, manufacturers, and users of flat panel displays, where virtually all aspects of information displays are presented. The organizers, Richard H. Bruce (Symposium Chair) and Hugo Steemers (Programme Chair) of Xerox Palo Alto Research Center, did a magnificent job in arranging a programme that covered a wide range of technology and applications' from high definition flat panel displays of both emissive and liquid crystal display (LCD) technology t o the latest in CRT development and large area display projection systems. The symposium featured over 180 papers from around the world in 45 technical sessions; the conference papers are published in the SID International Symposium Digest of Technical Papers Vol. XXVI. It is very apparent just by paging through the Digest of Technical Paper that LCDs have entrenched themselves in the flat panel display community, and as the need for high information content continues t o grow, LCDs are expected to play an even bigger role. From the liquid crystal materials perspective, the conference was heavily weighted towards reflective displays, polymer dispersed liquid crystal displays for projection, alignment and viewing angle issues, and active matrix technologies.     

Fabrication of half-polyimide-less liquid crystal device with fast response using reactive self-aligning amphiphile

ABSTRACT

We propose a new vertical alignment method for fast switching liquid crystal displays (LCDs) without the polyimide alignment layer on one side of a substrate. The key to this new method is the use of the amphoteric 2-carboxyethyl acrylate, which combines reactive acrylate and carboxylic acid groups to allow hydrogen bonding with substrate. The reactive group can achieve pre-tilt for a fast-switching of LC molecule, and the hydrogen bonding allow for vertical alignment of LC. The amphoteric material enables the manufacturing of cost-effective LCDs by reducing the number of steps in the process and fast switching by establishing pre-tilt alignment.     

ALIGNMENT INSTABILITY INDUCED BY IRRADIATION OF VISIBLE LIGHT IN FRUSTOELECTRIC LIQUID CRYSTALLINE CELLS SHOWING THE V-SHAPED SWITCHING

Abstract

Irradiation of the powerful visible light from the laser expedites the deterioration of the frustoelectric liquid crystalline cells (Inui mixture) showing the V-shaped switching. This deterioration is caused by the light absorption in the aligning layer, which strongly influences the molecule-surface polar interaction; this cannot be observed in the cell with the transparent aligning material in the used visible light region. This is observed just in the tilted smectic X* phase, not in the SmA phase. Irradiation during the switching leads to hysteresis in the V-shaped pattern and changes even the surface molecular alignment. These results can be explained by the shielding of the surface charge due to the alignment of the spontaneous polarization and the disturbed polar anchoring.     

Centre For Liquid Crystal Research,Bangalore

Abstract

Professor S. Chandrasekhar, Past President of the International Liquid Crystal Society, has founded a Centre for Liquid Crystal Research (CLCR), in Bangalore, thanks to the generous support received from Bharat Electronics Limited (BEL), the largest electronics company in the country, and from the Department of Electronics, New Delhi. The Centre was formally opened by the Vice President of India Mr K. R. Narayanan on 3 March, 1995. The activities of the Centre will be focused mainly on basic research, but due attention will be paid to applications as well, in particular, a link will be established between CLCR and BEL in the design and development of different types of LCD devices. CLCR will also be the headquarters of the Indian Liquid Crystal Society.