Low Molecular Mass Gelators of Organic Liquids and the Properties of Their Gels

A review was presented to demonstrate a historical description of the synthesis of light-emitting conjugated polymers for applications in electroluminescent devices. Electroluminescence (EL) was first reported in poly(para-phenylene vinylene) (PPV) in 1990 and researchers continued to make significant efforts to develop conjugated materials as the active units in light-emitting devices (LED) to be used in display applications. Conjugated oligomers were used as luminescent materials and as models for conjugated polymers in the review. Oligomers were used to demonstrate a structure and property relationship to determine a key polymer property or to demonstrate a technique that was to be applied to polymers. The review focused on demonstrating the way polymer structures were made and the way their properties were controlled by intelligent and rational and synthetic design.

Synthesis of Light-Emitting Conjugated Polymers for Applications in Electroluminescent Devices

Blue phases are types of liquid crystal phases that appear in a temperature range between a chiral nematic phase and an isotropic liquid phase. Because blue phases have a three-dimensional cubic structure with lattice periods of several hundred nanometres, they exhibit selective Bragg reflections in the range of visible light corresponding to the cubic lattice. From the viewpoint of applications, although blue phases are of interest for fast light modulators or tunable photonic crystals, the very narrow temperature range, usually less than a few kelvin, within which blue phases exist has always been a problem. Here we show the stabilization of blue phases over a temperature range of more than 60 K including room temperature (260–326 K). Furthermore, we demonstrate an electro-optical switching with a response time of the order of 10−4 s for the stabilized blue phases at room temperature.

Polymer-stabilized liquid crystal blue phases

Electrogenerated chemiluminescence (also called electrochemiluminescence and abbreviated ECL) is the process whereby species generated at electrodes undergo high-energy electron-transfer reactions to form excited states that emit light. The first detailed ECL studies were described by Hercules and Bard et al. in the mid-1960s, although reports concerning light emission during electrolysis date back to the 1920s by Harvey. After about 40 years study, ECL has now become a very powerful analytical technique and been widely used in the areas of, for example, immunoassay, food and water testing, and biowarfare agent detection. ECL has also been successfully exploited as a detector of flow injection analysis (FIA), high-performance liquid chromatography (HPLC), capillary electrophoresis, and micro total analysis (μTAS). Figure 1 illustrates a time line of various events in the development of ECL. A literature survey using SciFinder Scholar reveals that more than 2000 journal articles, book chapters, and patents on various topics of ECL have been published. The overall number of publications, as shown in Figure 2, has increased exponentially over the past 20 years, of which 40–50% were biorelated. Similar amounts of ECL papers could be also found from the Thomson ISI Web of Science as well as † Telephone (601) 266 4716; fax (601) 266 6075; e-mail wujian.miao@ usm.edu. Wujian Miao received his undergraduate diploma in chemistry from Nantong University (Nantong, China) in 1982, his M.Sc. degree in analytical chemistry from Zhongshan University (Guangzhou, China, with Jinyuan Mo) in 1991, and his Ph.D. degree in electrochemistry from Monash University (Melbourne, Australia, with Alan M. Bond) in 2000. He then served as a Research Scientist in CSIRO (Melbourne, Australia), followed by a postdoctoral fellowship at the University of Texas at Austin with Allen J. Bard in 2001. Since 2004 he has served as an assistant professor of chemistry at the University of Southern Mississippi.

Electrogenerated Chemiluminescence and Its Biorelated Applications

An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

We report the first observation of cholesteric blue phases in chiral anisotropic polymer networks. In two-component mixtures of a chiral and a non-chiral diacrylate, we observed typical textures of BPI, BPII and BPIII phases. By photopolymerization of these materials at constant temperature we obtained blue phase networks. After polymerization, the blue phases were stored, which enabled us to further study them without any temperature control.

Observation of blue phases in chiral networks

Charge transport and electroluminesence properties of colloidally synthesized CdSe/ZnS core–shell nanocrystal quantum dots (QDs) were studied. Nanocrystals were prepared using the conventional technique of pyrolisis of organometallic reagents in a hot coordinating solvent medium. Thin film diodes were produced by depositing a layer of QDs on top of a layer of conducting polymer poly (3,4-ethylenedioxythiophene): polystyrenesulfonate followed by the deposition of a metal electrode. For all the metals used in this study only a small rectification could be observed upon reversing the bias. The efficiency of the light generation showed strong dependence on the work function and bias of the metal electrodes, indicating that light generation in these devices is a result of recombination of injected holes and electrons. Assuming that the charge transport is due mainly to electrons, the voltage dependence of the current in QD composites could be explained by space charge limited current (SCLC) in the presence of ...

Study of conduction mechanism and electroluminescence in CdSe/ZnS quantum dot composites

A liquid crystalline material in the form of an anisotropic gel comprising a polymerized liquid crystalline material and a low-molecular weight liquid crystalline material, can be used in a display cell, said polymerized material forming a permanently oriented network in the low-molecular weight liquid crystalline material.

Liquid crystalline material and display cell containing said material

Mesomorphism and the molecular orientation of 1,4-phenylene bis{4-(6-(acryloyloxy)hexyloxy)benzoate} (1) and its derivative with a methyl-substituent in the central phenylene group (2) are studied. The methyl group affects the transition temperatures and the thermodynamic parameters, but not the order parameter of the monomers. The photoinitiated polymerization of the diacrylate monomers in their uniaxially oriented state leads to highly oriented and densely crosslinked polymer networks. The order parameter of these networks depends on the polymerization temperature, but becomes nearly temperature-independent after polymerization. The presence of the methyl group leads to a significant lower degree of order in the polymeric state. In addition, data are presented on the monomeric viscosity of 2 and on the tensile moduli, glass transitions and refractive indices of the oriented polymer networks. In order to extend the mesomorphous temperature range, mixtures of 1 and 2 are also investigated.

Insitu photopolymerization of oriented liquid-crystalline acrylates .4. influence of a lateral methyl substituent on monomer and oriented polymer network properties of a mesogenic diacrylate

A mirror device (1) which can be simultaneously used for display purposes based on e.g. an LCD display (5) with a polarizing mirror (2) placed in front of it. The orientation direction of a retardation layer (31, 32) is aligned with respect to the polarization direction of the polarizing mirror to give optimal optical performance.

Rifat Ata Mustafa Hikmet

Papers

Observation of blue phases in chiral networks

Study of conduction mechanism and electroluminescence in CdSe/ZnS quantum dot composites

Liquid crystalline material and display cell containing said material

Insitu photopolymerization of oriented liquid-crystalline acrylates .4. influence of a lateral methyl substituent on monomer and oriented polymer network properties of a mesogenic diacrylate

Mirror with built-in display