Electrophoretic Fluid Research Articles

Preparation of 3D network CNTs-modified nickel foam with enhanced microwave absorptivity and application potential in wastewater treatment

Multi-walled carbon nanotubes (MWCNTs) modified nickel foams (MWCNTs-NF) were developed with an electrophoretic deposition methodology for microwave (MW) assisted catalysis and processing enhancement. A nickel foam (NF) was selected to serve the dual purpose both as the MW absorbing catalytic materials and the matrix for MWCNTs loading in order to maximize the recyclability of the catalysts. The effects of electrophoretic voltage and concentration of electrophoretic fluid on the morphology and deposition characteristics of MWCNTs on the NF matrix were investigated. It was found that the MWCNTs-NF composite material resulted in strong enhancement of MW absorptivity with synergistic heat-generating effects that were not observed when MWCNTs or NF was exposed to MW alone. The combination of NF and MWCNTs brought a catalytic total organic carbon removal efficiency of 97% in wastewater treatment, while that using bare MWCNTs and NF were only 65.2% and 79.3%, respectively. The coupling of NF with MWCNTs led to the formation of additional MW-absorbing channels and focal sites with strong MW absorptivity, which in turn gave rise to the synergistic MW heating effects. This research highlights the great prospect of the MW-assisted reaction enhancement using the MWCNTs-NF composite material as the catalyst in wastewater treatment and other similar engineering applications.

Preparation of environment friendly gelatin–arabic gum microcapsules in Isopar M system for electrophoretic display

A series of functional microcapsules for electrophoretic display (EPD) prepared by complex coacervation technology utilising gelatin and arabic gum as a wall material are presented. The authors have investigated the Isopar M electrophoretic fluid containing blue-white, red-white and yellow-white particles modified by the physical coating as core materials of microcapsules, respectively. The mass ratio of wall/core material is a key factor influencing the yield of microcapsules. The surface of microcapsule was characterised by optical microscopy and scanning electron microscopy. The display prototypes based on the red-white, blue-white and yellow-white microencapsulated electrophoretic fluids have been prepared. The contrast ratios of prototypes were found to be 1.62, 1.67 and 1.22, respectively.

42-4:Invited Paper: A Full-Color Electrophoretic Display

Full color electrophoretic displays utilizing colored particles, no color filter array, and a single TFT array backplane have been demonstrated for the first time. A full color gamut including all eight primary colors has been achieved with a single layer of electrophoretic fluid addressed with voltages compatible with commercially demonstrated TFT backplanes. Displays have been made with incorporation of the electrophoretic fluid into both Microcup® and microcapsule structures.

Preparation and Characterization of Microcapsule-Encapsulated Colored Electrophoretic Fluid in Trifluorotoluene System for Electrophoretic Display

Trifluorotoluene was used as a liquid suspending fluid for electrophoretic display (EPD). The dispersion stability, chargeability, and response time of electrophoretic particles suspended in trifluorotoluene were investigated. Hyperdispersant and assistant hyperdispersant (CH-11B) could provide satisfactory dispersion stability in trifluorotoluene electrophoretic fluid. The contrast ratio of simple electrophoretic display devices reached 2.95, 3.93, and 1.41, respectively, and the response time was 305 ms/348 ms, 512 ms/415 ms, and 140 ms/371 ms, respectively. All of the devices remained stable within 30 min after outage. The coating process using the method of screen printing was studied with trifluorotoluene microcapsules as coating materials. The counts of mesh and coating layer were key factors influencing the performance of coating. Microcapsule type EPD prototypes showed outstanding display results without coating defects.

纳米金刚石掺混纳米氧化锌的场发射特性

Chrysanthemum-like Zinc Oxide(ZnO)nanorods was fabricated and characterized by hydrothermal route,the diamond was mixed to prepare electrophoretic fluid.After electrophoretic fluid was dispersed by ultrasonic cleaning machine,the coatings were deposited on titanium substrates.Field emission characteristics were tested after heat treatment.Results show that turn-on field of undoped diamond cathode is 7.3V/μm and field emission current density is 81μA/cm2 when electric field is set at20V/μm,while the doped samples show low turn-on field of 4.7~6.0V/μm and high field emission current density of 140~158μA/cm2.The reason is that after the interfusion of nano-ZnO,the electron transport capacity of coating is enhanced,the number of effective emitters increase and field enhancement factorβis improved.Because of diamond,the good bonding between coating and substrate is guaranteed after heat treatment and ohmic contact is formed,which reduces the thermal effect of field emission current.The stability of field emission current declines with the increasing amount of mixed ZnO.Both field emission current density and its stability should be considered,so mixing an appropriate amount of ZnO with nano-diamond can effectively improve field emission characteristics.

Encapsulation of organic yellow pigment particles via miniemulsion polymerisation procedure and their application in electrophoretic displays

Pigment yellow 13/polystyrene (PY13/PS) composite particles were prepared using a miniemulsion polymerisation procedure. PY13 was suspended into the monomer phase styrene. The resultant oil suspension was added to deionised water with emulsifier sodium dodecyl benzene sulphonate (SDBS) and converted into stable miniemulsion. The miniemulsion was then polymerised using initiator Potassium peroxydisulphate (KPS). The Fourier transform infrared spectroscopy and transmission electron microscopy showed that the pigments were encapsulated by polystyrene (PS); the scanning electron microscopy indicated that the composite particles have spherical morphology and smooth surface. The particle size analysis suggested that the size distribution can be very narrow by changing the concentration of SDBS and styrene. The modified particles were used as electrophoretic particles in electrophoretic fluid with stabilizer CH-5 and charge control additive T151, and the yellow–white dual colour electrophoretic display cells were successfully made.

Synthesis and Characterization of Surface Modified Red Pigment 48:2 for Electrophoretic Display

Red Pigment 48:2 (PR 48:2) was coated with polyethylene (PE). The chemical constitution of the modified pigments was identified by fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FE-SEM). The modified particles have good dispersity and high electrophoretic mobilities. For a simple EPD device, the contrast ratio of red-white electrophoretic fluid reached 2.60.

Luminescent Electrophoretic Particles via Miniemulsion Polymerization for Night-Vision Electrophoretic Displays

A novel glowing electrophoretic display (EPD) is achieved by luminescent electrophoretic particles (EPs), which is potentially to improve the situation in which the existing EPDs disable in darkness. To combine both modes of reflective and emissive displays, a trilayer luminescence EP is designed and synthesized via an improved miniemulsion polymerization. The luminescence EP is composed of a pigment core, a polystyrene interlayer, and a fluorescent coating. The particle sizes are from 140 to 170 nm, and the size distribution is narrow. Their ζ potential value is -12.4 mV, which is enough to migrate in the electrophoretic fluid by the driving of an electric field. The display performance of the particles in an EPD cell has been characterized under the bias of 20 V. Both the reflectance (491 nm) and fluorescence (521 nm) intensities of the EPD cell remained in a constant range after 30 switches.

Preparation and application of microcapsule-encapsulated color electrophortic fluid in Isopar M system for electrophoretic display

The use of Isopar M as a liquid suspending fluid for electrophoretic display was studied. The dispersion stability and chargeability of pigments suspended in Isopar M were investigated. Polyisobutylene monosuccinimide (T-151) as the charge control additive in Isopar M electrophoretic fluid can provide a good electrophoretic mobility to the particles. The wall materials of a series of blue–white, red–white and yellow–white dual-particle microcapsules were prepared by in situ polymerization of urea and formaldehyde. The mass ratio of wall/core material was a key factor in influencing the yield of microcapsules. The concentration of resorcinol has an impact on the surface morphology and mechanical strength of microcapsule wall. Microcapsules’ surface morphologies were characterized by optical microscopy and scanning electron microscopy. The performance of the microcapsules with different binder materials and adhesive layers were investigated. Contrast ratio of microcapsules display device were tested every 10days for a period of 90days. The compatibility of Isopar M with both the electrophoretic particles and bounding capsule was studied.

Synthesis and characterisation of urea–formaldehyde microcapsules containing electrophoretic fluid with red–white particles

A series of functional microcapsules were prepared via in situ polymerisation technology with poly(urea–formaldehyde) resin as wall material and electrophoretic fluid containing red–white particles as core materials. The urea–formaldehyde microcapsules were characterised by optical microscopy, scanning electron microscopy and particle size analysis. It was found that sodium dodecyl sulphate (SDS) plays an important role in the formation of the microcapsule wall, and the concentration of SDS mainly affects the yield and surface feature of the microcapsules. The microcapsules prepared with SDS concentration of 2·5×10−3 mM at a dispersing stirring rate of 600 rev min−1 demonstrated good surface topography and suitable sizes. These microcapsules were applied successfully to prepare a clock display operated at a direct current voltage of 20 V, demonstrating that these microcapsules are potential candidates for applications in the area of electrophoretic displays.

The electric response behavior and microencapsulation of the pigment phthalocyanine green G using interfacial polymerization

The polyamide microcapsules for the electrophoretic display have been prepared via interfacial polymerization. The core material of the microcapsules is electrophoretic fluid consisted of pigment phthalocyanine green G (CAS No. 1328-53-6) modified with octadecylamine, tetrachloroethylene, and polyoxyethylene octylphenol ether (OP-10). The wall of the polyamide is synthesized from paraphthaloyl chloride and diethylenetriamine. FT-IR indicated that octadecylamine was bonded to pigment phthalocyanine green G with the hydrogen bond. The effect of the amount of octadecylamine on the dispersibility of the pigment suspended in tetrachloroethylene was investigated. Compared to the unmodified pigment, the dispersibility of the modified pigment was improved by 66.7%. The modified pigment migrated to the positive electrode under the direct voltage and the electric response time was about 85 s in 20 V/mm. The average particle size of microcapsules decreased from 834.5 to 258.2 nm as the dosage of OP-10 increased, and the microcapsule yield reached maximum of 83.5% at the OP-10 concentration of 1.5 wt%. With the reduction of the core/wall weight ratio in the range from 1:6 to 1:14, the average particle size improved from 267.4 to 554.4 nm. However, the maximum of the microcapsule yield was 87.6% at the core/wall weight ratio of 1:10. The microcapsule yield reached a peak of 87.6% as the pH value was 12. The average particle size of the microcapsules that obtained at 25 °C was 327.4 nm, which was smaller than those prepared in other temperatures. The formed polyamide microcapsules had a regular spherical shape.

Gelatin/carboxymethylcellulose/dioctyl sulfosuccinate sodium microcapsule by complex coacervation and its application for electrophoretic display

We have described the microcapsules containing electrophoretic fluid as core material, prepared from gelatin, sodium carboxymethylcellulose (NaCMC) and dioctyl sulfosuccinate sodium (DSS) by complex coacervation method. The gelatin/NaCMC/DSS microcapsules are characterized by optical microscopy (OM), scanning electron microscopy (SEM), particle size analysis and thermogravimetric analysis (TGA). It is found that DSS plays an important role in the formation of the microcapsule wall and the concentration of DSS deeply affects the yield of microcapsules by enhancing the interaction between gelatin and NaCMC. The microcapsules prepared with DSS content of 0.6 mM show compact capsule wall which endows the capsules with good barrier property and high thermal stability. These microcapsules are applied successfully to prepare a 4-in. clock display panel controlled by single-chip microprocessor (SCM) operated at a low direct current (DC) voltage of 3 V, demonstrating that these microcapsules are potential for the applications in the area of electrophoretic displays.

The electrophoretic softness of the surface of Staphylococcus epidermidis cells grown in a liquid medium and on a solid agar.

Many Staphylococcus epidermidis strains possess capsule or slime layers and consequently the staphylococcal cell surface should be regarded as a soft, polyelectrolyte layer allowing electrophoretic fluid flow through a layer of fixed charges. The presence of such a soft layer decreases the energy barrier due to electrostatic repulsion in the interaction of the organisms with negatively charged substrata [Morisaki, H., Nagai, S., Ohshima, H., Ikemoto, E. & Kogure, K. (1999), MICROBIOLOGY: 145, 2797-2802] and hence plays an important role in their adhesion. In this paper, the authors compare the electrophoretic softness and amount of fixed charge in the outer cell surface layers of 20 S. epidermidis strains, grown in a liquid medium or on a solid agar, as determined from the dependencies of their electrophoretic mobilities upon the ionic strength of a suspending fluid. Most of the staphylococcal cell surfaces were relatively soft, with a mean cell surface softness (1/lambda) for strains grown in liquid medium of 1.7+/-0.6 nm (standard deviation over all 20 strains) which is soft by comparison with a completely bald, peptidoglycan-rich streptococcal cell surface (1/lambda=0.7 nm). When the staphylococcal strains were grown on solid agar, the cell surface softness of 17 of the 20 strains increased, sometimes by a factor of two. On average for 20 strains, the cell surface softness increased significantly (P:<0.05, Student's t-test) to 2.8+/-1.8 nm. The amount of fixed charge in the outer cell surface layer was -28+/-9 mM for bacteria grown in liquid medium and -24+/-12 mM for bacteria grown on agar. A soft, highly negatively charged polyelectrolyte layer was inferred by microelectrophoresis for all the staphylococcal cell surfaces, regardless of whether staining had indicated the presence of a capsule or slime layer.