Following Sharpless' visionary characterization of several idealized reactions as click reactions, the materials science and synthetic chemistry communities have pursued numerous routes toward the identification and implementation of these click reactions. Herein, we review the radical-mediated thiol-ene reaction as one such click reaction. This reaction has all the desirable features of a click reaction, being highly efficient, simple to execute with no side products and proceeding rapidly to high yield. Further, the thiol-ene reaction is most frequently photoinitiated, particularly for photopolymerizations resulting in highly uniform polymer networks, promoting unique capabilities related to spatial and temporal control of the click reaction. The reaction mechanism and its implementation in various synthetic methodologies, biofunctionalization, surface and polymer modification, and polymerization are all reviewed.

Thiol–Ene Click Chemistry

Micromachining technology was used to prepare chemical analysis systems on glass chips (1 centimeter by 2 centimeters or larger) that utilize electroosmotic pumping to drive fluid flow and electrophoretic separation to distinguish sample components. Capillaries 1 to 10 centimeters long etched in the glass (cross section, 10 micrometers by 30 micrometers) allow for capillary electrophoresis-based separations of amino acids with up to 75,000 theoretical plates in about 15 seconds, and separations of about 600 plates can be effected within 4 seconds. Sample treatment steps within a manifold of intersecting capillaries were demonstrated for a simple sample dilution process. Manipulation of the applied voltages controlled the directions of fluid flow within the manifold. The principles demonstrated in this study can be used to develop a miniaturized system for sample handling and separation with no moving parts.

Micromachining a miniaturized capillary electrophoresis-based chemical analysis system on a chip

Polymers for flexible displays: From material selection to device applications

An overview is given of theory and experiments on liquid crystal phases which appear in solutions of elongated colloidal particles or stiff polymers. The Onsager (1949) virial thecry for the isotropionematic transition of thin rodlike particles is treated comprehensively along with extensions to polydisperse solutions and soft interactions. Computer simulations of liquid crystal phases in hard particle fluids are summarized and used to assess the quality of statistical mechanical thwries for stiff panicles at higher dume haion-like the inclusion of higher Virial coefficients, yexpansion, scaled particle theory and density functional theory. Both computer simulations and density functional theory indicate formation of more highly ordered smectic phases. The range of experimental applicability h strongly widened by the extension of the viriai theory to wormlike chains by Khokhlov and Semenov (1981, 1982). Fmally, experimental results for a number of carefully studied, charged and uncharged colloids and polymers are summarized and wmpared to theoretical results. IE many cases the agreement is semi-quantitative.

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Phase transitions in lyotropic colloidal and polymer liquid crystals

The English-language dictionary defines wrinkles as "small furrows, ridges, or creases on a normally smooth surface, caused by crumpling, folding, or shrinking". In this paper we review the scientific aspects of wrinkling and the related phenomenon of buckling. Specifically, we discuss how and why wrinkles/buckles form in various materials. We also describe several examples from everyday life, which demonstrate that wrinkling or buckling is indeed a commonplace phenomenon that spans a multitude of length scales. We will emphasize that wrinkling is not always a frustrating feature (e.g., wrinkles in human skin), as it can help to assemble new structures, understand important physical phenomena, and even assist in characterizing chief material properties.

Soft matter with hard skin : From skin wrinkles to templating and material characterization

We develop a simple and versatile platform to construct the surface nanotopography of a substrate by thermal fixation of colloidal particles. The micrometer-size particles of polystyrene are dispersed in a random monolayer on a substrate by spin-coating and transformed into hemispherical nanostructures with high mechanical stability under thermal treatment. The experimental results for the structural change of the particles agree well with the calculations in a simple model of the constant-volume. The liquid crystal (LC) alignment on the nanotopographic surface with hemispherical structures is found to increase the symmetry of the electro-optic properties of the LC devices. The colloidal particle-based surface topography with size-scalable nanostructures provides a practical route to the control of interfacial structural orders of the functional molecules on a nanometer-to-micrometer scale. V C 2012 American Institute of Physics.

Colloidal particle-based surface nanotopography with high mechanical stability by thermal fixation for liquid crystal devices

A new type of a reflective liquid crystal display is proposed in a twisted hybrid aligned (THA) geometry. In this reflective configuration, a single polarizer and a reflective electrode are used to improve brightness and viewing characteristics. The electro-optical switching between the black and white states is easily achieved in the THA geometry. Numerical simulations are carried out to find the optimum cell parameters such as the cell thickness and the amount of twist required for a stable THA structure. The reflective THA cell provides wider viewing and faster dynamic characteristics than a reflective twisted nematic cell. The effect of a retardation film on device performances is also discussed.

Reflective liquid crystal displays in a twisted hybrid geometry

A method for manufacturing an optical sensor includes forming a reflective metal layer on a substrate, forming an insulator layer on the reflective metal layer, inducing self-assembly of a metal nanostructure layer on the insulator layer, and selectively etching the insulator layer through a reactive ion etching process to form a plurality of pillars and a plurality of spaces defined by the plurality of pillars. The method for manufacturing a plasmonic optical sensor according to this embodiment facilitates the formation of nanostructures difficult to pattern and form on the large scale at a low cost, and provides a plasmonic optical sensor with repeatability.

Optical sensor, manufacturing method thereof, and fluid analysis method using the same

We have developed a transflective liquid crystal display (LCD) having a single cell gap and a single LC mode by adopting a patterned retardation layer. In our transflective configuration, a single LC mode of the 60° twisted nematic LC was used for both transmissive and reflective applications. The patterned retardation layer was fabricated using a reactive mesogen by photo-patterning. The measured electro-optic characteristics of our transflective LC cell agree well with numerical simulations. Particularly, the transmittance was found to show similar behavior to the reflectance.

68.2: A Transflective Liquid Crystal Display Having a Patterned Retardation Layer

The brightness improvement of a transflective liquid crystal display in a unified configuration, having a single-cell gap and a vertically aligned (VA) liquid crystal (LC) mode, was demonstrated. The photo-patterned retarder was used to compensate the optical path difference between the transmissive and reflective regions. It was made of a UV-polymerizable liquid crystal (LC) through a single patterning process. High reflectance and fast response characteristics were achieved in our unified configuration.

Sin-Doo Lee

Papers

Colloidal particle-based surface nanotopography with high mechanical stability by thermal fixation for liquid crystal devices

Reflective liquid crystal displays in a twisted hybrid geometry

Optical sensor, manufacturing method thereof, and fluid analysis method using the same

68.2: A Transflective Liquid Crystal Display Having a Patterned Retardation Layer

P‐161: Brightness Improvement of Transflective LCD in a Unified Configuration