Flexible cellulose derivative PDLC type cells

In this work we perform a study of 250 μm thick flexible electro-optical PDLC type cells made from a biocompatible cellulose derivative film and several conductive substrates. The deposition of an ITO layer by reactive thermal evaporation on a polymeric substrate was referred to in the literature very recently and this type of coated substrate was used in the present work. In order to consider the influence of the substrates on the electro-optical behaviour of the cells, five cells were made using different substrates (three flexible polymers and two glass for comparison). Three of the substrates were coated under the same conditions, and the other two were commercially available substrates.     

Anisotropic hydroxypropylcellulose films as alignment layers of a bistable ferroelectric device

Hydroxypropylcellulose films are used as the alignment substrate in a liquid crystal bistable electro-optical device. These alignment films were characterized by atomic force microscopy. The electro-optical behaviour of this device, which operates in the Clark-Lagerwall mode, is identical to that observed for typical SSFLC cells. In particular the bistability of the cell was clearly observed, the threshold voltage was measured and an estimation of the anchoring energy of the LC mixture used, in this type of system, was made.     

Anisotropic hydroxypropylcellulose films as alignment layers of a bistable ferroelectric device

Hydroxypropylcellulose films are used as the alignment substrate in a liquid crystal bistable electro-optical device. These alignment films were characterized by atomic force microscopy. The electro-optical behaviour of this device, which operates in the Clark-Lagerwall mode, is identical to that observed for typical SSFLC cells. In particular the bistability of the cell was clearly observed, the threshold voltage was measured and an estimation of the anchoring energy of the LC mixture used, in this type of system, was made.     

Study of electro-optical properties of liquid crystal/reactive mesogen-coated liquid crystal display fabricated by slit coater

We have recently proposed a slit coater method for printable liquid crystal (LC) devices. In this method, the LC/reactive mesogen (RM) mixture was directly coated uniaxially onto the substrate surface by shear flow between the slit nozzle and the substrate, and the liquid crystalline molecules were anchored by in situ photopolymerisation of RM monomers. In this study, the dependence of electro-optical properties and device parameters of LC sample cells fabricated by the slit coater on ultraviolet (UV) exposure dosage was investigated. Moreover, effects of UV exposure dosage and thermal annealing on the azimuthal anchoring energy of LC sample cells fabricated by the slit coater are presented.     

Study of polymer-stabilised blue phase liquid crystal on a single substrate

One outstanding feature of the polymer-stabilised blue phase (PSBP) is that it is unnecessary to form an alignment film, which requires a high-temperature baking process. Therefore, PSBPs may enable flexible liquid crystal displays (LCDs) on plastic substrates. In this study, polymer stabilisation of a blue phase (BP) on a single substrate was performed without using a conventional sandwich-type cell, and the electro-optical properties are demonstrated to be similar to those of a sandwich-type PSBP LCD cell. It was experimentally shown that the oxygen which inhibits radical polymerisation is required to be excluded in order to complete the polymer stabilisation in blue phase.     

Syntheses and characterization of functionalized polynorbornene dicarboximides for flexible substrates

In this study, we synthesized polynorbornene (PNB) dicarboximides substituted by monochlorophenyl group (PMCPhNDI) and dichlorophenyl group (PDCPhNDI) via ring‐opening polymerization using a ruthenium catalyst and investigated their thermal, mechanical, and optical properties. We also discussed the performance and application of the functionalized PNB dicarboximide films as flexible substrates for organic light‐emitting devices (OLEDs). The polymer films exhibited good optical transparency with an average transmittance of around 97% in the visible light region and good thermal stability with a 5% degradation temperature of >440°C. The polymers were applied for flexible displays, which were coated on indium tin oxide (ITO) thin films using a radio‐frequency planar magnetron sputtering system with changing the deposition substrate temperatures. A flexible OLED that was fabricated on the ITO‐grown polymer substrates exhibited a performance as comparable to the corresponding ITO‐grown glass substrates. Copyright © 2012 John Wiley & Sons, Ltd.     

High‐strength electrically conductive fibers: Functionalization of polyamide,aramid, and polyester fibers with PEDOT polymer

In this work, high‐performance fibers such as aramid (Twaron), polyamide (PA6), polyester (PET), and hybrid Twaron/PA6 fibers were transformed into electroactive fibers by coating them with conjugated polymer, poly(3,4‐ethylenedioxythiophene) (PEDOT) through vapor phase polymerization (VPP) method. The VPP is considered as an efficient technique for depositing CPs on different substrates regardless of their lower solubility in various solvents. In this paper, PEDOT‐coated high‐performance fibers were prepared under already optimized reaction conditions, and then a comparison between electrical, thermal, and mechanical properties of different fibers, before and after coating, was made. The obtained coated fibers were characterized through scanning electron microscope (SEM), thermogravimetric analysis (TGA), 2‐probe electrical resistance measurement method, and tensile testing. It was revealed that at particular reaction conditions, all high performance textile substrates were successfully converted into electroactive fibers. The voltage‐current (V‐I) characteristics showed that PEDOT‐coated polyester fibers exhibited highest conductivity value among all other substrate fibers. The active PEDOT layers on high performance fibers could behave as an antistatic coating to minimize the risks associated with static charges at work places. Also, the obtained fibers have potential to be used as smart materials for various medical, sports, and military applications.     

Polymer Membranes Dispersed Liquid Crystal (PMDLC): a new electro-optical device

Polymer Dispersed Liquid Crystals (PDLCs) are liquid crystal dispersions in a polymer matrix, which look like opaque in their OFF state, when no electric field is applied, and transparent in their ON state. They are generally obtained by a phase separation process, such as Thermal, Solvent- and Polymerization-Induced Phase Separation (TIPS, SIPS and PIPS, respectively), between two transparent conductive glass substrates. In this paper, a new electro-optical device, formed by a porous polymer membrane imbibed with liquid crystal by capillary suction, is presented (Polymer Membranes Dispersed Liquid Crystals, PMDLC). Polymer membrane surfaces were made conductive before liquid crystal loading by magnetron sputtering of a thin layer of conductive indium tin oxide. The morphology and the electro-optical response of these devices were investigated and the observed transmittances and relaxation times were found to be similar to those of conventional PDLCs. In addition, PMDLCs showed interesting flexibility as no solid conductive substrate is required and economic convenience as there is no loss of liquid crystal in the polymer matrix.     

The electro-optic properties of colloidal silica filled nematics

The optical and electro-optical properties of filled nematic liquid crystals, nematic systems with added colloidal silica nanoparticles (? 6%), have been studied. The macroscopic near IR birefringence of cells constructed from these materials was measured for wavelengths between 2 and 5 mum, and a wavelength independent value of 0.16 was obtained. The visible optical behaviour of cells formed with untreated ITO substrates using both filled nematic, and filled nematic and dichroic dyes was similar to those observed in polymer dispersed liquid crystals. At an electric field of 1–2 V μm ^-1, the cells were highly transmitting, while at low fields they were highly scattering. The effects of colloidal silica nanoparticle concentration, cell thickness, electric field and substrate preparation (rubbed polyimide versus no surface treatment) on the electro-optical behaviour of these cells were studied.     

Interfacial chemistry of adhesives on hydrated aluminium and hydrated aluminium treated with an organosilane

The adsorption of a commercial adhesive and two of its major components—an amine curing agent [2,4‐toluene diisocyanate urone (TDI urone)] and an adhesive prepolymer resin [diglycidyl ether of bisphenol A (DGEBA)]—on a hydrated aluminium surface and the hydrated surface coated with γ‐glycidoxypropyltrimethoxysilane (GPS) has been investigated by x‐ray photoelectron spectroscopy (XPS) and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). The study of TDI urone adsorption indicated that adsorption was of the chemisorption type, and a specific interaction involving this molecule and the GPS immobilized on the hydrated aluminium surface was identified. From XPS and ToF‐SIMS data it was found that the types of interaction of the curing agent with the bare substrate were of the donor–acceptor type. Study of the DGEBA adsorption showed different‐shaped isotherms for the bare and the GPS‐coated substrates. It was found that the typical Langmuir isotherm type was obtained for the GPS‐coated substrate whereas no adsorption plateau was observed for the bare substrate within the concentration range studied. This resulted from a change in the conformation of the DGEBA molecule on the substrate when the concentration of DGEBA solution was increased. The bonding of DGEBA with both types of substrates was assumed to be via acid–base interactions (i.e. donor–acceptor interactions). Adsorption of the commercial adhesive on the hydrated surfaces was of BET Type IV form, rather than the simple monolayer adsorption isotherm (Langmuir type). This indicates multilayer adsorption, presumably in the pores of the hydrated substrate, as a result of a process analogous to adsorption condensation. Copyright © 2004 John Wiley & Sons, Ltd.     

The electro-optic properties of colloidal silica filled nematics

The optical and electro-optical properties of filled nematic liquid crystals, nematic systems with added colloidal silica nanoparticles ( ≤6%), have been studied. The macroscopic near IR birefringence of cells constructed from these materials was measured for wavelengths between 2 and 5 mum, and a wavelength independent value of 0.16 was obtained. The visible optical behaviour of cells formed with untreated ITO substrates using both filled nematic, and filled nematic and dichroic dyes was similar to those observed in polymer dispersed liquid crystals. At an electric field of 1-2 V μm -1 , the cells were highly transmitting, while at low fields they were highly scattering. The effects of colloidal silica nanoparticle concentration, cell thickness, electric field and substrate preparation (rubbed polyimide versus no surface treatment) on the electro-optical behaviour of these cells were studied.     

Surface‐Coated Thermally Expandable Microspheres with a Composite of Polydisperse Graphene Oxide Sheets

Surface‐modified thermally expandable microcapsules (TEMs) hold potential for applications in various fields. In this work, we discussed the possible surface coating mechanism and reported the properties of TEMs coated with polyaniline (PANI) and polydisperse graphene oxide sheets (ionic liquid‐graphene oxide hybrid nanomaterial (ILs‐GO)). The surface coating of PANI/ ILs‐GO increased the corresponding particle size and its distribution range. The morphologies analyzed by scanning electron microscopy indicated that no interfacial gap was observed between the microspheres ink and substrate layer during the substrate application. The thermal properties were determined by thermogravimetric and differential thermal analyses. The addition of ILs‐GO to the polyaniline coating significantly improved the thermal expansion and thermal conductivity of the microcapsules. The evaporation of hexane present in the core of TEMs was not prevented by the coating of PANI/ ILs‐GO. The printing application of TEMs showed excellent adaptability to various flexible substrates with great 3D appearance. By incorporating a flame retardant agent into TEMs coated by PANI/ILs‐GO, finally, these TEMs also demonstrated a great flame retardant ability. We expect that these TEM‐coated PANI/ ILs‐GO are likely to have the potential to improve the functional properties for various applications.     

建立在硫醇分子电化学替换组装基础上的纳米粒子区域化组装

利用金基底电位变化时硫醇自组装膜的吸脱附性质, 通过改变基底电位和组装溶液, 用电化学方法在金基底上实现了传统自组装技术难以实现的硫醇分子的替换组装; 通过金基底的分区化设计, 用控制电位的组装技术在基底的不同微区内制备了不同末端官能团的硫醇及其衍生物自组装膜; 并在此基础上实现了纳米粒子的区域化组装.     

Protein films adsorbed on experimental dental materials: ToF-SIMS with multivariate data analysis

The proteins lysozyme, amylase, and bovine serum albumin (BSA) were adsorbed on two experimental dental materials, made of fluoroapatite particles embedded in polymer matrices, and on silicon wafers. The protein films were prepared as single-component layers, as binary mixtures, and as double layers. These systems were investigated by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and the multivariate data analysis technique of discriminant principal-component analysis (DPCA). During adsorption of a single protein film on to the solid surfaces, the three proteins could be clearly distinguished by the scores of their mass spectra after selection of amino acid-related peaks and DPCA. Furthermore, very similar results were obtained on the two different fluoroapatite substrates. For samples coated with binary layers of two proteins adsorbed simultaneously, it was found for both substrate types that BSA shows the strongest ability to adsorb followed by lysozyme, while amylase has the smallest ability. By contrast, the consecutive adsorption of two protein layers showed a strong influence of substrate type on the adsorption ability of the proteins.     

Comments on the wetting behavior of non-porous substrates for ceramic coated-conductor applications

This work gives an overview of the possibilities to improve the wetting behavior of precursors for coated conductors on non-porous substrates. Within this work, all coatings were performed on a metallic Ni–W/La₂Zr₂O₇/CeO₂ substrate using water-based Y, Ba, Cu containing precursors. The results described in this paper can be used for different technologies of chemical solution deposition, as there are ink jet printing, dip coating, spin coating etc. Starting from the forces involved during wetting, a separation between solid and liquid modifications was made. This study revealed that if a good cleaning procedure of the substrate, whether or not combined with a targeted modification of the precursor is applied, water-based solutions can be used without restriction towards their wetting behaviour leading to a sustainable technology within the coating industry. Within this work, special attention is given to (1) fast determination of the substrate cleaning procedure quality by the creation of wetting envelopes and (2) the use of a screening design of experiment to study the effects of intrinsic solution factors, such as precursor formulation, influencing the coating behavior. All modification discussed are expandable to all kinds of precursors and substrates.     

A simple transflective liquid crystal display with composite dielectric layer

ABSTRACT

A simple transflective liquid crystal display with a vertically aligned cell using a composite dielectric layer is demonstrated. The top substrate has a top planar common electrode, two transparent dielectric layers with different dielectric constants are coated on the bottom planar pixel electrode to generate linearly varying electric potential from the transmissive region (T region) to the reflective region (R region), while two bumpy reflectors are coated under the bottom substrate. In this device, with the composite dielectric layer, the common and pixel electrodes generate a strong electric potential in the T region and a relatively weak electric potential in the R region. Consequently, the T and R regions accumulate the same electro-optical characteristics. The simulation results show that the display exhibits reasonably low operating voltage, high optical efficiency and well-matched voltage-dependent transmittance (VT) and reflectance (VR) curves. Besides, the driving mode and the fabrication process of the transflective liquid crystal display are fairly simple and it is suitable for mobile applications.     

Photoactivation of a substrate for cell adhesion under standard fluorescence microscopes

Cell-culturing substrates where cell adhesion can be switched on by external stimuli during cell cultivation are useful scaffolds for tissue engineering, cell-based drug screening, and fundamental cellular studies. Here, we show a new strategy for photoactivation of a substrate for cell adhesion under standard fluorescence microscopes. A glass substrate chemically modified with an alkylsiloxane having a photocleavable 2-nitrobenzyl group was coated with bovine serum albumin to prevent cell adhesion. Upon irradiation under a fluorescence microscope, the protein was replaced with fibronectin, which made the irradiated region cell-adhesive. Subsequent seeding of HEK293 or COS7 cells produced patterns corresponding to the irradiated patterns. We succeeded for the first time in positioning single cells in proximity to cultivating single cells. The present method provides a general strategy for positioning single cells of same or different types at any locations on the substrate and will be useful for studying cell-cell interactions.     

Growth substrate induced functional changes elucidated by FTIR and Raman spectroscopy in in–vitro cultured human keratinocytes

Non-invasive measurements of cellular function in in vitro cultured cell lines using vibrational spectroscopy require the use of spectroscopic substrates such as quartz, ZnSe and MirrIR etc. These substrates are generally dissimilar to the original in vivo extracellular environment of a given cell line and are often tolerated poorly by cultured cell lines resulting in morphological and functional changes in the cell. The present study demonstrates various correlations between vibrational spectroscopic analyses and biochemical analyses in the evaluation of the interaction of a normal human epithelial keratinocyte cell line (HaCaT) with MirrIR and quartz substrates coated with fibronectin, laminin and gelatin. The findings of this study suggest that there is a correlation between quantitative measurements of cellular proliferative capacity and viability and peak area ratios in FTIR spectra, with replicated differences in similar areas of the observed Raman spectra. Differences in the physiology of cells were observed between the two spectroscopic substrates coated in fibronectin and laminin, but little differences were observed when the cells were attached to gelatin-coated quartz and MirrIR slides. The correlations demonstrate the sensitivity of the spectroscopic techniques to evaluate the physiology of the system. Furthermore the study suggests that gelatin is a suitable coating for use in spectroscopic measurements of cellular function in human keratinocytes, as it provides a material that normalises the effect of substrate attachment on cellular physiology. This effect is likely to be cell-line dependent, and it is recommended that similar evaluations of this effect are performed for those combinations of spectroscopic substrate and cell lines that are to be used in individual experiments.     

Evaluation of nucleic acid duplex formation on gold over layers in biosensor fabricated using Czochralski-grown single-crystal silicon substrate

With a view to developing an economical and elegant biosensor chip, we compared the efficiencies of biosensors that use gold-coated single-crystal silicon and amorphous glass substrates. The reflectivity of light over a wide range of wavelengths was higher from gold layer coated single-crystal silicon substrates than from glass substrates. Furthermore, the efficiency of reflection from gold layers of two different thicknesses was examined. The thicker gold layer (100 nm) on the single-crystal silicon showed a higher reflectivity than the thinner gold film (10 nm). The formation of a nucleic acid duplex and aptamer–ligand interactions were evaluated on these gold layers, and a crystalline silicon substrate coated with the 100-nm-thick gold layer is proposed as an alternative substrate for studies of interactions of biomolecules.     

强极性色谱固定相硅膜改性弹性玻璃毛细管柱的研制

本工作研究了强极性OV-275固定液可以直接涂渍在硅膜改性弹性玻璃毛细管上,研制的柱子具有良好的色谱特性。该柱的柱效,惰性以及热稳定性均优于弹性石英毛细管柱。