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We report a graphene oxide (GO)-based composite, featuring GO/cross-linking agent (CA) nanoparticles, inspired by a nacre-like hierarchical structure present in nature. The as-prepared GO/CA composite was powdered to nanoscale particles and then mixed with pure GO to be GO/CA/GO (GCG) composite forming hierarchical GO/CA nanoasperities on the GO surface. The strength and toughness of the nacre-inspired GCG composite films were simultaneously improved by adjusting the nanoparticle concentration and hierarchical level of the GO-based films. Compared to pristine GO films and GO/CA composites, which exhibit a low level of hierarchy in their structures, the tensile strength and toughness of the GCG composites with higher hierarchy were enhanced 3.1 and 1.6 times and 47.6 and 10.9 times, respectively. Furthermore, a plausible mechanism of increasing mechanical properties based on nanoscale asperities and homogeneous interactions between GO and CA has been discussed.

One of the major challenges in the field of nanotechnology is the facile and inexpensive fabrication of

Many petals in nature have a hierarchical structure that imparts various optical properties. Among these, the petals of the Queen of the Night tulip exhibit an iridescent and glossy color due to the diffraction and scattering of light. Herein, we report a bioinspired micro-/nanohierarchical structure that mimics Queen of the Night tulip petal surfaces. Using a method that combined soft lithography and UV-ozone treatment, we fabricated nanoscale line patterns with a linewidth of 600 nm on microwrinkles of 15 μm width and 3 μm height. Using optical microscopy in the dark-field mode and monochromatic light diffraction measurements, we found that these hierarchical structures on a poly(dimethylsiloxane) (PDMS) substrate synergistically improved the scattering and diffraction effects, unlike the pristine, nano-, and microstructures. In addition, using a dye-colored PDMS material, we fabricated artificial Queen of the Night petals with iridescent and glossy effects. They show great potential for a range of applications, such as coloring, smart displays, dynamic gratings, and light-control devices.

We report a graphene oxide/cross-linking agent (GO/CA) composite inspired by the nacre structure. Based on the "brick-and-mortar" concept of nacre, graphene oxide and a cross-linking agent are covalently conjugated in the form of nacre. The mechanical characteristics of the nacre-mimetic GO/CA composite film can be controlled by adjusting the preparation method, degree of cross-linking, and cross-linking times. As a result, the cross-linking strategy can drastically enhance the tensile strength [142.9 ± 6.4 MPa (∼2.3-fold)], modulus [4.7 ± 0.36 GPa (∼15.7-fold)], and hardness [917.4 ± 85.7 MPa (∼9.0-fold)], which are superior to those of pristine materials. The cross-linking agent-based chemical bonding method for mechanically improved integration is mainly attributed to the formation of strong cross-linked networks between the GO-based 2D interfaces and CA. The facile fabrication process provides many opportunities to design advanced, robust, and integrated nacre-like GO/CA composites, which can be applied to future aerospace utilizations, electronic protectors, robotic elements, and permeable membranes.

Aesthetically appealing photovoltaic (PV) panels with colorful layers are used in numerous applications involving color matching with the surroundings. To develop a colored film for a PV system, appropriate optical properties such as high transparency and low angle sensitivity are necessary because the colored layers can reduce the efficiency of the PV system by causing variations in the transmittance and angle of incidence. Herein, we propose a facile fabrication method for bioinspired three-dimensional (3D) photonic crystal (PC) films that exhibit broad angle-insensitive transmission and reflection, for application in colorful PV. This structure, patterned on a sequentially stacked 11-layer film of SiO

A simple method was reported to fabricate self-cleaning and water–oil separation fabrics sprayed with hot-iron-treated graphene oxide (GO). The GO solution was prepared with a modified Hummers' method and coated on the fabrics by spraying or soaking method. A 160 °C hot iron was pressed at the surface of the fabrics to make it flat, dry, thermally reduced in part, and strongly bonded. Afterward, the fabrics were thermally reduced at 250 °C for 20 minutes in an oven. The reduced graphene oxide (rGO) coated fabrics exhibited a superhydrophobic nature with a water contact angle of 129.4°, through which water could barely permeate the fabrics, in contrast to oil and organic solvents of low polarity. Additionally, this rGO fabric presented outstanding mechanical properties as well as a reusable stability.

It is well known that Morpho butterflies show distinctive, brilliant and iridescent colors and have micro-nano scale structures, instead of dyes and pigments, on their wings. This structural coloration is regarded as a novel technique to express color with a long lifetime, ease and precise tenability. Here, we studied optical multilayer thin films with thickness of several tens of nm (TiO

Silver grid electrode is a promising candidate for transparent conductive film because of its outstanding electrical, thermal, and optical properties, which can be easily tuned by changing the line width, spacing, and thickness of the metal pattern. Here, we presented the fabrication method of transparent Ag electrode with line-pattern using contact transfer technique with thermal release tape (TRT) that is easy to adhere and/or release to the substrate. To fabricate a line-patterned Ag electrode, the following efficient processes were developed: 1) preparation of line-patterned recess using thermal-roll imprinting, 2) surface modification by the anti-adhesion layer coating, 3) Ag infilling into the line-patterned recess using a doctor blade, 4) transfer of Ag electrode to the target substrate using TRT. As a result, the Ag line-patterned film with low sheet resistance (17.94 Ω/sq) and high transparency (90.28% at 550 nm) was obtained. This film can be tailored on requirement for various electronic applications.

Graphene oxide membrane (GOM) has attracted extensive attraction as a molecular sieve for the separation of water, ions, and gases. However, A-level control of the GOM interlayer spacing for separating the specific size of gas molecule is difficult and the vertical transport mechanism of molecules through the GOM is highly complex because of the existence of several possible pathways. Here we fabricated GOMs with different A-scale interlayer spacing through heat treatment and made them allow horizontal entrance and transport of gas molecules. The GOMs with angstrom channels exhibited superior performance in permeance in horizontal mode and moderate selectivity for H2/CO2 and He/CO2 by tuning the sieving size of the channels. Molecular dynamics (MD) simulations reveal that the precisely controlled interlayer spacing plays a primary role as a molecular sieve indeed, but increased graphitic area, a result of heat treatment, also affects observed selectivity. Our results provide insight into the transport mechanism of gas molecules through GO nanochannel, which has not been accurately identified due to its complex behavior and suggest the possibility of studying nanochannels as effective vehicle for separating molecules precisely.

Monolayer graphene grown by chemical vapor deposition has been intensively studied for applications such as transparent conductive films, electronic devices, sensors, molecular barriers, and electrodes. However, technology to transfer monolayer graphene from metal film must be improved through environmentally friendly and non-defective methods on arbitrary target substrates. Here, we report a clean and direct method for transferring monolayer graphene from Cu foil without defects and over a large area. In a water bath at 90–95 °C, we floated Cu foil with graphene on the water surface. After 5 h, a Cu2O layer formed uniformly at the interface between the graphene and the Cu. Subsequently, the monolayer graphene on the Cu foil was delaminated from the thermal release tape, releasing the graphene to the target substrate (SiO2/Si and PET). The Cu2O formation and defect changes were monitored at each step via various characterization methods. The Cu2O layer was uniformly established and no defects were generated after the transfer. Finally, we fabricated a graphene field effect transistor that exhibited an excellent electronic performance.

In this study, we used GO (graphene oxide) in order to enhance the adhesion between Ag NWs (nanowires) and substrates. By using a mixture solution of GO and Ag NW, a vacuum filtration process was used to fabricate a 50nm diameter thin film. Next, by using a light annealing process, the mechanical and electrical stability of Ag NW network was improved without any other treatment. The physical properties of the Ag NW - GO hybrid transparent conductive thin film was characterized in terms of a bending test, resistance and transmittance test, and nanoscale imaging using field-emission scanning electron microscopy.

Graphene oxide (GO) membranes have attracted attention as a promising candidate for selective ion permeation due to narrow interlayer spacing. Among several methods to control the interlayer spacing, the reduction of GO membranes has great potential for desalination and water purification. To apply GO membranes for ion separation, investigating ion transport of sub-nanometer channels of reduced GO membranes is needed. In this study, thermally and chemically reduced GO membranes were fabricated with different interlayer spacing ranging from 3.7 to 8.0 A in a dry state. It was experimentally determined that the minimum spacing allowing water permeation was 5.7 A (9.6 A in water), and no water permeated at 5.0 A or less. For ion permeation, a pure GO membrane exhibited similar permeability for most ions, while the permeability of GO membrane with 5.7 A spacing was strongly dependent of the size and charge of ions. The permeability of cations significantly changed along with the ionic radius, while there was a noticeable cutoff for permeability of multivalent anions such as SO42− and Fe(CN)63−. Our reduced GO membrane could be used to effectively block the permeation of large ions and multivalent anions.

We present a pressure-conductive rubber sensor using a liquid-metal-polydimethylsiloxane (PDMS) composite suitable for incorporation onto surfaces with a complex curvature such as the human body. The composite is synthesized by physical mixing of Galinstan and PDMS based on magnetic stirring. This composite is conductive only when a mechanical pressure exceeding the threshold value or strain is applied; the pristine state of the composite is not conductive. The threshold value can be controlled by adjusting the mixing ratio of liquid metal and PDMS. This material is mechanically robust, allowing it to operate reliably under various elastic deformations such as pressing, stretching, and bending without structural failure and performance degradation. Moreover, a fabricated sensor array can detect the distribution of the applied pressure in plane. As a feasibility study, we demonstrate a pressure-conductive rubber sensor for detecting finger movements and bio-signals such as blood pressure and respiration rate. Our results reveal that our rubber sensor is practical as a wearable sensor because of its mechanical robustness and electrical reliability.

We report colorimetric, label-free, and non-aggregation-based gold nanoparticle (AuNP) probes for the highly selective detection of Fe(III) ions in aqueous environments. This detection scheme relies on the ability of Fe(III) ions to catalyze the leaching of gold at room temperature in the presence of thiourea species and hydrochloric acid. The catalytic leaching of the AuNP probes results in rapid and remarkable damping of the surface Plasmon band and hence induces a visible color change which can be easily detected through naked eye. This simple and cost-effective probe provides rapid detection of Fe(III) ions at concentrations as low as 50 ppm and expected to be effective to design efficient environmental and biological sensor.

We report ambivalent rejection behavior of a graphene oxide membrane (GOM) having a reduced interlayer spacing. Ultrathin GOMs having a thickness of 50 nm were fabricated using a vacuum filtration method followed by subjecting the samples to thermal reduction at 162 °C. The interlayer spacing of GOMs was reduced by 1 A on thermal reduction as compared with that of the natural GOMs. The rejection rate with dye molecules was tested using dyes having three different types of charges in a dead-end filtration instrument. Rejection rate of the reduced GOM with the dyes having an opposite charge was improved up to 99.7%, indicating the dominant effect of the physical sieving diameter. In contrast, in the case of ion permeation of natural GOM, a higher rejection rate for several metal ions was observed as compared with that of GOMs having 1 A smaller interlayer spacing, indicating the dominant effect of surface charges on the GOM samples.

We report a colorimetric system for the detection of HCl in aqueous environments using unlabeled gold nanoparticle (AuNP) probes. This nonaggregation-based detection system relies on the ability of chloro species to cause rapid leaching of AuNPs in an aqueous dispersion containing a strong oxidizing agent, such as HNO(3) or H(2)O(2). The leaching process leads to remarkable damping of the surface plasmon resonance peak of the AuNP dispersion. This method works only with AuNPs of a particular size (∼30 nm diameter). It is highly selective for HCl over several common mineral acids, salts, and anions. This simple and cost-effective sensing system provides rapid and simple detection of HCl at concentrations as low as 500 ppm (far below the hazard limit) in natural water systems.

This paper reports on the enhanced photoluminescence (PL) of nanocomposites through the layered structuring of phosphor and quantum dot (QD). Green phosphor of Sr2SiO4:Eu, red QDs of CdSe/CdS/CdZnS/ZnS core-multishell, and thermo-curable resin were used for this study. Two kinds of composite (layered and mixed) were prepared, and the schemes for optical energy transfer between QD and phosphor were suggested and investigated based on PL decay characteristics. It was found that the layered structure is more effective than the mixed one with respect to PL intensity, PL decay, and thermal loss. When this layered nanocomposite (QDs on phosphor) is used to make a white light emitting diode (LED), the brightness is increased by 37%, and the color rendering index (CRI) value is raised to 88.4 compared to the mixed case of 80.4.

A combination of thermal oxidation and thermal recovery was used to obtain transparent single-walled carbon nanotube (SWCNT) films with low sheet resistance. The process resulted in the effective removal of impurities and healing of defects in the SWCNTs, thus markedly increasing their conductivity. SWCNT samples before and after the process were analyzed by Raman spectroscopy, scanning and transmission electron microscopy, thermogravimetric analysis, contact angle measurement, and transparent conductive film fabrication. Following purification, the sheet resistance decreased from 5380 to 187 Ω/sq at 80% optical transmittance and at a wavelength of 550 nm. The process requires a short time of about 3 h and produces 30% yield of the as-produced sample.

The grating formation dynamics, SEM images, diffraction efficiency, and electrooptical properties of transmission grating of holographic polymer dispersed liquid crystals (HPDLCs) have been investigated by incorporating three different types of monofunctional reactive diluents into the host polymer matrices. A gradual increase of real time diffraction efficiency, a decrease of LC droplet size, and an increase of diffraction efficiency of the composite film were obtained with the addition of epoxy acrylate monomers due to the increased viscosity of polymer/LC mixtures leading to decreased droplet coalescence. In addition, epoxy acrylate monomers induced decreased volume shrinkage according to their ring structure with bulky group. Driving voltage increased with the addition of epoxy monomers whereas rise time and decay time decreased as a result of the decreased LC droplet size. At an optimum composition of epoxy monomer, a minimum switching voltage of 6V)μm -1 and rise time of 0.15 ms and a decay time of 18.05 ms were respectively obtained.

We investigate thermal behavior of transparent film heaters (TFH) made of single-walled carbon nanotubes. We fabricate the TFH by using the spray coating method. We studied the temperature dependence of the electrical resistance of the TFH in terms of Joule and external heating in various gas environments. Test results show that the effect of the electrical current through the TFH on the temperature dependence of the electrical resistance is not important and that the humidity and the degree of vacuum significantly affect the shape of the resistance−temperature curve. We discuss the physical meanings underlying the experimental results and how to make use of these findings. This study improves the understanding of the heating effect on electrical conductance of the TFH made of single-walled carbon nanotubes which could be a good candidate for the heater in many applications requiring both transparency and heating function.

Conventional formulation of holographic polymer dispersed liquid crystal (HPDLC) has been doped with TiO2 nanoparticles. It was found that local electric field across the LC domain was effectively increased by the TiO2 inclusion in polymer, and the film was electrically driven. Typical inverted sigmoidal decrease to a constant value was obtained with and above 0.1 wt% TiO2. On the other hand TiO2 increased formulation viscosity, giving rise to slow grating formation, low saturation diffraction efficiency, and large decay time of the film. It was also found that resin composition of polyurethane acrylate (PUA)/N‐vinyl‐pyrrollidinone (NVP) = 1.5:1 (by weight) gave closer solubility parameter to TiO2, rapid grating formation, and lower switching voltage than PUA/NVP = 1:1 due to the high reactivity and closer solubility parameter of the resin to TiO2.

BACKGROUND: To reduce the driving voltage of transmission holographic polymer-dispersed liquid crystals (HPDLCs), the polymer interface was modified by incorporating various amounts of vinyloxytrimethylsilane (VOTMS) monomer to the conventional grating formulation based on polyurethane acrylate (PUA). RESULTS: With the addition of increasing amounts of VOTMS, the contact angle of the film and the droplet size of the liquid crystal (LC) monotonically increased, implying that the VOTMS segments of the polymer are preferentially exposed to the interfaces and provide greater immiscibility with LC molecules. The operating voltage monotonically decreased with increasing VOTMS content with a minimum switching voltage of about 15 V with a response time of about 10 ms. However, in the presence of VOTMS, the droplets coalesced and caused random scattering, thus lowering the off-state diffraction efficiency below that of virgin PUA. CONCLUSION: It was found that VOTMS was essential to drive the film. The VOTMS segments of the polymer are preferentially exposed to the polymer/LC interfaces and decrease the surface anchoring strength and also influence the orientation of LC droplets. Also, lower molecular weight bifunctional polypropylene glycol generally gave greater diffraction efficiency, confirming that grating formation is favoured with higher crosslink density due to the greater polymer/LC phase separation. Copyright © 2008 Society of Chemical Industry

Films were made by incorporating various quantities of fluoroalkyl acrylate (FA) into the chain termini of polyurethane acrylate oligomer of polymer stabilized cholesteric liquid crystals (PSCLCs). The effects of switching voltage, scanning electron and polarized optical microscope morphologies, texture transition and reversibility, and contact angle of the films were then studied. It was found that the switching voltage of the film decreased with the addition of FA up to 0.8 wt%, beyond which it increased. The decrease and increase were respectively explained in terms of decreased interface energy as noted from the contact angle of the LC on polymer surface, and too small droplet size as noted from the SEM. Copyright © 2008 John Wiley & Sons, Ltd.

The grating formation dynamics, morphology and electro‐optical properties of transmission gratings of holographic polymer dispersed liquid crystals (HPDLCs) were investigated based on partial fluorination of the host polymer matrices by incorporating three different types of fluorinated monomer. Addition and increasing amounts of fluorinated monomer gave short saturation time and increased off‐state diffraction efficiency with a maximum due to the chemical incompatibility between fluorinated compounds and LC, whereas the droplet size increased with increasing fluorinated monomer content. In addition, fluorinated monomer induced decreased switching voltage and increased response time due to the low anchoring energy at the polymer–LC interfaces and increased droplet size. At an optimum content of fluorinated monomer, a minimum switching voltage of 5 V µm−1, a rise time of 0.25 ms and a decay time of 23.15 ms were obtained.

Transmission gratings of holographic polymer dispersed liquid crystals (HPDLCs) have been designed and fabricated based on partial fluorination of the polymer matrix using three types of fluorinate...

BACKGROUND: A slight change of polymer structure leads to a significantly different solubility parameter (SP), which is related to incompatibility and interface anchoring energy between a polymer and a liquid crystal (LC). RESULTS: Holographic gratings in polymer-dispersed liquid crystals have been fabricated based on various urethane acrylate oligomer sizes and type of reactive diluent at two LC loadings. A large SP gap, using N-vinylpyrrolidone as reactive diluent, gave much faster saturation of diffraction efficiency at higher level, but the grating failed to operate. On the contrary, films having a small SP gap, using 2-ethylhexyl acrylate, operated under 20 V with a response time of about 10 ms, although their saturation of diffraction efficiency was relatively low. The results were interpreted in terms of morphology (determined using scanning electron microscopy), anchoring energy and resin elasticity. CONCLUSION: Low driving voltage and high diffraction efficiency are obtained by controlling the SP gap between LC and polymer. Copyright © 2007 Society of Chemical Industry

Effects of high dielectric anisotropy compound (MLC) and oligomer molecular weight on the grating formation and electro-optical properties of transmission holographic polymer dispersed liquid crystal (HPDLC) have been studied. Addition of MLC reduced the response time and switching voltage with the increased formulation viscosity which introduced a sequence of phenomenon, i.e. slow diffusion, polymerization, phase separation, grating formation, and droplet coalescence giving small droplet size and enhanced diffraction efficiency of the film. Apparently, increase in oligomer molecular weight gave effects similar to those of increasing MLC content since both variables control droplet coalescence through different mechanisms.

The low surface energy and the great immiscibility of poly (dimethylsiloxane) (PDMS) with liquid crystals (LCs) are used in the fabrication of holographic polymer dispersed liquid crystals (HPDLCs). By adding increasing amounts of PDMS, the extent of the phase separation between the polymer and the LC, the LC channel width, and-eventually-also the diffraction efficiency of the film can be increased, while keeping the droplet size essentially the same. In addition, the presence of PDMS causes a decrease in the switching voltage and an increase in the response time. At an optimum content of PDMS (PUA40), a minimum switching voltage of 4 V microm(-1), a rise time of 0.20 ms, and a decay of 14.75 ms were obtained. Regarding the effect of the LC content, an overshoot of the diffraction efficiency was observed when the amount of LC exceeded 35 %, which can be attributed to droplet coalescence.

The effects of poly(vinyl carbazole) (PVK) doped to a poly(urethane acrylate) matrix in holographic-polymer-dispersed liquid crystals were studied. With the addition and increasing amounts of PVK, the driving voltage and rising time of the films decreased because of the increased effective local electric field across the liquid crystal (LC) droplet. Off-state diffraction efficiency was increased with the addition and increasing amounts of PVK presumably because of the increased elasticity of the polymer matrix, which augmented the phase separation of the polymer and LC by effectively squeezing the LC molecules out of the polymer matrix. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Rheological, thermal, and mechanical properties of polypropylene homo polymer (PPH)/amorphous poly alpha olefin (APAO) blends as a function of molecular weight, comonomer type and content, and blend composition have been investigated. Homo APAO grade showed better compatibility than copolymerized ones in terms of rheological and thermal properties. The mechanical strength showed strong dependence on APAO content and type, and the impact strength and melt index rapidly increased for certain types of APAO at and above 30 wt%. On comparison with commercially used PPH/ethylene–propylene rubber (EPR) blend system, it is supposed that PPH/APAO blend can be successfully used in thermoplastic polyolefin applications. Copyright © 2007 John Wiley & Sons, Ltd.

Chiral dopants were added to the formulation of holographic polymer‐dispersed liquid crystals and the effects studied in terms of grating formation dynamics, morphology, diffraction efficiency, contrast ratio and electro‐optical properties of the films. A gradual increase of real‐time diffraction efficiency, decrease of droplet size and increase of diffraction efficiency of the composite film were obtained with the addition and increasing content of chiral dopant, due to the increased viscosity of the liquid crystal (LC) doped with the chiral dopant leading to decreased droplet coalescence. The contrast ratio decreased with increasing content of chiral dopant due to the difficult orientation of LC molecules caused by the formation of a helical structure. Addition of a small amount of the chiral dopant increased the driving voltage slightly, whereas the decay time is decreased significantly as a result of the high twisting of the helical structure.

Effects of octanoic acid (OA) on the morphology, diffraction efficiency, and electro-optic properties of the transmission mode of holographic polymer-dispersed liquid crystals (HPDLC) are studied. Droplet size decreases with increasing OA content (0-9 %), and this leads to a monotonic increase in off-state diffraction with increasing OA content. However, on-state diffraction decreases with increasing applied voltage and shows a minimum at 6 % OA, for which minimum switching voltage (5 V microm(-1)) and maximum contrast ratio (10) are obtained. Rise time and decay time decrease with increasing OA content. Interposition of OA between polymer and LC droplet is theoretically predicted by the spreading coefficient (lambda>0) calculated on the basis of the solubility parameter, while the coalescence behavior of droplets is described by a dimensionless group (gamma d rho / mu(2)) called coalescence number.

Doping of conductive fullerene particles to the formulation of conventional holographic polymer dispersed liquid crystal-induced dual effects of reducing both droplet coalescence and operating voltage. Fullerene induced an induction period which otherwise does not exist, followed by a gradual increase of diffraction efficiency to a saturation value being increased with increasing fullerene content. The increased diffraction efficiency was caused by the decreased droplet coalescence which was due to the hindered migration of LC by the fullerene particles. On the other hand, doped fullerene particles augmented the conductivity of polymer phase and hence the local electrical field imposed on LC droplet, which overcome the threshold for driving and reduced operating voltage and response times. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5590–5596, 2007

Recently, the lack of clean and safe drinking water is huge challenge because of rapid population growth, severe droughts and environmental pollution. Two-dimensional Graphene oxide (GO) membrane with their ultrafast permanence, outstanding mechanical properties, high chemical stability is increasingly emerging as promising candidate for water purification process. But GO-based water purification technology still needs further investigation and optimization. Here, we fabricated ultrathin graphene oxide membrane by the vacuum filtration method, and successfully applied for the water purification. GO membranes with several tenth nm thickness prepared show well stacked layer structure, as characterized by atomic force microscopy and scanning electron microscopy. We have tried pressure-driven filtration to examine water flux, retention and rejection ability of the GO membranes in water purification process. The ultrathin graphene oxide membrane showed high retention and rejection rates for the charged dyes and moderate results for noncharged organic dye.

Nanosized silicas added to holographic polymer-dispersed liquid crystals (HPDLC) provide the resin phase with increased elasticity, dimensional stability, and the high diffraction efficiency of the gratings. On the other hand, nucleation and growth of periodic modulation are delayed, especially with small-sized silica because of the increased viscosity of the resin mixture. Effects of the LC/resin composition and cell gap on the diffraction efficiency have also been studied.

We report a facile and efficient method to transfer the graphene from a metal substrate to a polymer without removal of the metal substrate. Multilayer graphene was synthesized on a Co substrate, and liquid polydimethylsiloxane (PDMS) was prepared using various curing agent ratios. The quantity of graphene transferred to the cured PDMS could be controlled by the mixing ratio of the curing agent. We produced monolayer graphene on a metal substrate and controlled the transfer of graphene layers to PDMS.

Here, we report highly transparent and flexible AgNW/SWCNT hybrid networks on PET substrates combined with plasmonic welding for securing ultrahigh stability in mechanical and electrical properties under severe bending. Plasmonic welding produces local heating and welding at the junction of AgNWs and leads strong adhesion between AgNW and SWCNT as well as between hybrid structure and substrate. The initial sheet resistance of plasmon treated AgNW/SWCNT hybrid film was 26 Ω sq(-1), with90% optical transmittance over the wavelength range 400-2700 nm. Following 200 cycles of convex/concave bending with a bending radius of 5 mm, the sheet resistance changed from 26 to 29 Ω sq(-1). This hybrid structure combined with the plasmonic welding process provided excellent stability, low resistance, and high transparency, and is suitable for highly flexible electronics applications, including touch panels, solar cells, and OLEDs.

The long-term stability of quantum dot (QD)-based devices under harsh environmental conditions has been a critical bottleneck to be resolved for commercial use. Here, we demonstrate an extremely stable QD/alumina/polymer hybrid structure by combining internal atomic layer deposition (ALD) infilling with polymer encapsulation. ALD infilling and polymer encapsulation of QDs synergistically prohibit the degradation of QDs in terms of optical, thermal and humid attacks. Our hybrid QD/alumina/polymer film structure showed no noticeable reduction in photoluminescence even in a commercial grade test (85% humidity at 85 ° C) over 28 days. In addition, we successfully fabricated a QD-based light-emitting device with excellent long-term stability by incorporating hybrid QD/alumina/polymer film as a color conversion material on light-emitting diode chips.

We report the measurement of fluid velocity on a semiconducting single-walled carbon nanotubes film in a microfluidic channel. To investigate the mechanism related to electrical signal change, we performed various experiments along with changing the flow velocity, the ion concentration and liquid viscosity, etc. Our result suggests that the sensing of flow velocity is a closely related to a pulsating asymmetrical thermal ratchet model. The electric signal change was strongly dependent on the electrode alignment, and the channel width of the sample. As the result, we achieved highly sensitive detection of the fluid, roughly 4 times greater than previous results.

The fabrication of nanostructures having diameters of sub-5 nm is very a important issue for bottom-up nanofabrication of nanoscale devices. In this work, we report a highly controllable method to create sub-5 nm nano-trenches and nanowires by combining area-selective atomic layer deposition (ALD) with single-walled carbon nanotubes (SWNTs) as templates. Alumina nano-trenches having a depth of 2.6 ∼ 3.0 nm and SiO2 nano-trenches having a depth of 1.9 ∼ 2.2 nm fully guided by the SWNTs have been formed on SiO2/Si substrate. Through infilling ZnO material by ALD in alumina nano-trenches, well-defined ZnO nanowires having a thickness of 3.1 ∼ 3.3 nm have been fabricated. In order to improve the electrical properties of ZnO nanowires, as-fabricated ZnO nanowires by ALD were annealed at 350 °C in air for 60 min. As a result, we successfully demonstrated that as-synthesized ZnO nanowire using a specific template can be made for various high-density resistive components in the nanoelectronics industry.

We report colorimetric, label-free and non-aggregation-based gold nanoparticle (AuNP) probes for the highly selective detection of Cu(II) ions in aqueous environments. This detection scheme relies on the ability of Cu(II) ions to catalyze the leaching of gold at room temperature in the presence of thiosulfate species and ammonia. This simple and cost-effective probe provides rapid detection of Cu(II) ions at concentrations as low as 10 ppm. A similar detection method using AuNPs in ammonia-free thiosulfate solution is also viable at moderate reaction temperature (50 °C). The ammonia-free method also leads to marked damping and red-shifting of the surface plasmon resonance signal of the AuNP dispersion. The two methods clearly differ in the nature of the surface plasmon damping phenomenon, and their working mechanisms are plausibly explained based on the experimental investigations.

We fabricated transparent film heaters using single-walled carbon nanotubes (SWCNTs) and investigated their heating performance. We studied thermal behavior of the transparent film heaters by using thermal cyclic experiment. We discussed physical meanings underlying the experimental results and how to make use of the findings. The transparent conducting film using SWCNTs could be a good candidate for the heater in many applications requiring both heating function and transparency.