Deposition of electrically conductive ceria/polypyrrole nanocomposite particles on flexible polyethylene naphthalate film via in situ photo-induced polymerization

To achieve a flexible and transparent conductive film via a simple method, ceria/polypyrrole nanocomposite particles were coated on Piranha-treated polyethylene naphthalate (PEN) film as the flexible substrate. Photo-induced polymerization was carried out by cerium (III) nitrate hexahydrate dissolved in acetonitrile and irradiation by UV wavelengths for 2 h. The effect of Piranha treatment on deposition of the conductive nanocomposite particles was examined. Deposited PEN samples prepared at various conditions were characterized using FESEM, AFM and STM, UV–vis spectroscopy, four-probe conductivity and contact angle measurements. Adhesion quality of the deposited nanoparticles was investigated by Scotch-tape test.     

Synergistic enhancement of dielectric constant of novel core/shell BaTiO3@MWCNTs/PEN nanocomposites with high thermal stability

In this work, the multi-walled carbon nanotubes (MWCNTs) cores were coated with inorganic BaTiO₃ (denoted as BaTiO₃@MWCNTs) via solvent-thermal method. Then, BaTiO₃@MWCNTs/polyarylene ether nitriles (PEN) nanocomposite films embedded with core/shell BaTiO₃@MWCNTs nanotubes were successfully prepared by solution-casting method. Pure PEN film, MWCNTs/PEN and BaTiO₃/PEN films were prepared for comparison. The micromorphology, thermal, and dielectric properties of the nanocomposite films were investigated. All the nanocomposite films exhibited excellent thermal stability endowed by PEN matrix. Interestingly, it was found that core/shell BaTiO₃@MWCNTs exhibited synergistic enhancement of dielectric constant of BaTiO₃@MWCNTs/PEN nanocomposite films.     

Using Graphene Oxide to Enhance the Barrier Properties of Poly(lactic acid) Film

The ultra‐thin (polyethyleneimine/graphene oxide)_n [(PEI/GO)_n]multilayer films on poly(lactic acid) (PLA) were constructed via the layer‐by‐layer assembly. Here, the electrostatic interactions between PEI and GO were used to obtain the nanoscale composite membrane of (PEI/GO)_n on the surface of PLA film. With the number of assembling layers increased, the oxygen permeability (PO₂) of PLA film decreased substantially. As a 0.06 wt% GO solution was used with only four layers, the PO₂ decreased from 53.8 to 0.377 × 10^?4 cm³/m²/d/Pa, only 0.7% of the original PLA film. At the same time, the coated PLA film also presented a good transparency and better mechanical properties. It is a novel way to use GO on biodegradable packaging materials. Copyright © 2014 John Wiley & Sons, Ltd.     

Surface modification of titanium thin film with chitosan via electrostatic self-assembly technique and its influence on osteoblast growth behavior

Chitosan (Chi) and poly (styrene sulfonate) (PSS) were employed to surface modify titanium thin film via electrostatic self-assembly (ESA) technique in order to improve its biocompatibility. The surface chemistry, wettability and surface topography of the coated films with different number of deposited layers were investigated by using X-ray photoelectron spectroscopy (XPS), water contact angle measurement and atomic force microscopy (AFM), respectively. The results indicated that a full surface coverage for the outmost layer was achieved at least after deposition of five layers, i.e., PEI/(PSS/Chi)₂ on the titanium films. The formed multi-layered structure of PEI(PSS/Chi) _x (x ≥ 2) on the titanium film was stable in air at room temperature and in phosphate buffered solution (PBS) for at least 3 weeks. Cell proliferation, cell viability, DNA synthesis as well as differentiation function (alkaline phosphatase) of osteoblasts on chitosan-modified titanium film (PEI/(PSS/Chi)₆) and control sample were investigated, respectively. Osteoblasts cultured on chitosan-modified titanium film displayed a higher proliferation tendency than that of control (p < 0.01). Cell viability, alkaline phosphatase as well as DNA synthesis measurements indicated that osteoblasts on chitosan-modified titanium films were greater (p < 0.01) than those for the control, respectively. These results suggest that surface modification of titanium film was successfully achieved via deposition of PEI/(PSS/Chi) _x layers, which is useful to enhance the biocompatibility of the titanium film.     

The fabrication of the antibacterial paste based on TiO2 nanotubes and Ag nanoparticles-loaded TiO2 nanotubes powders

ABSTRACT

We successfully synthesised TiO₂ nanotubes (TNTs) and silver nanoparticles (Ag NPs)-loaded TiO₂ nanotubes paste. These were coated on a glass substrate by spin coating method, and their antibacterial activities were surveyed. The morphology of materials was defined by transmission electron microscopy (TEM) image; the crystalline structure and the composition of the materials were determined by X-ray diffraction (XRD) pattern and X-ray photoelectron spectroscopy (XPS). Vibrational properties of the molecules existing in the sample were investigated by Fourier transform infrared (FTIR) spectroscopy, and the transmittances of films were determined by UV–Vis transmittance spectroscopy. This research shows that the structure and morphology of TNTs did not change after they underwent the processes of paste preparing and film coating on a glass substrate. Furthermore, the transmittance of TNTs film (about 75%) is higher than Ag NPs-loaded TiO₂ nanotubes (Ag/TNTs) film (about 65%) in the visible region. Moreover, the antibacterial property of Ag/TNTs film shows its effectiveness against Escherichia coli bacteria, and the antibacterial efficiency is 99.06% for 24 h-incubation period in the dark condition.     

Preparation and characterization of poly(arylene ether nitriles)/glass fibers/BaTiO3 ternary composites

Poly(arylene ether nitriles) (PEN) copolymers PEN (HQ/RS) was synthesized using 2,6-dicholorobenzonitrile (DCBN) with equal molar of hydroquinone (HQ) and resorcin (RS). Composites of PEN reinforced by glass fiber (GF) and nanometer-sized BaTiO₃ particle were prepared through melt blending. Both mechanical and thermal properties of the composites were found improved with the increase of GF as well as BaTiO₃ contents. For PEN/GF/BaTiO₃ ternary composites, the best mechanical properties were found when the content for GF and BaTiO₃ is 8 wt.% and 22 wt.%, respectively. The fractured surfaces of PEN/BaTiO₃ composites were examined with SEM and show a characteristic of ductile fracture. The heat distortion temperature (HDT) of 35 wt.% GF reinforced composite is 241 °C, nearly an increase ca. 100 °C compared to that of the pristine resin.     

Ferroelectricity of ultrathin ferroelectric Langmuir-Blodgett polymer films on conductive LaNiO3 electrodes

LaNiO₃ (LNO) films with a surface roughness rms of 0.384 nm and a sheet resistance of about 200 Ω were prepared on SrTiO₃ and Si/SiO₂ substrates respectively by rf magnetron sputtering technique. The surface of LNO on Si/SiO₂ substrate is smoother than that on SrTiO₃ substrate. A nominal 2-monolayer (ML) poly(vinylidenefluoride-trifluoroethylene) film with a thickness of about 3 nm was deposited on LNO coated Si/SiO₂ substrate by Langmuir-Blodgett (LB) technology. Piezoresponse force microscopy (PFM) measurements show that the LB films demonstrate an obvious feature of polarization switching and good voltage durability. The results suggest that the ultrathin polymer films may be utilized to explore ferroelectric tunnel junctions.     

Preparation of TiSi nanowires by APCVD used for improving dielectric properties of PST thin film

Nanoelectrode of conductive TiSi nanowires with Ti₅Si₃ conductive bottom layer underneath is prepared on glass substrate by atmosphere pressure chemical vapor deposition (APCVD) method. Pb_0.4Sr_0.6 (Ti_0.97 Mg_0.03) O_2.97 (PST) thin film is deposited on the nanoelectrode by rf-sputtering method. The morphology and phase structure of the nanoelectrode are measured by FE-SEM and XRD, respectively. The dielectric property of a PST thin film deposited on the nanoelectrode substrate is obtained by Agilent 4294A Impedance Analyzer. The results show that the conductive Ti₅Si₃ crystalline phase bottom layer is formed at deposition temperature above 710 °C, and the conductive TiSi single crystal nanowires are formed on the bottom layer perfectly in this case. By using the substrate on which the TiSi nanowire planted Ti₅Si₃ electrode is prepared, the PST thin film is deposited and it exhibits the high tunability of approximately 61% which is much higher than that deposited on the Ti₅Si₃ coated glass substrates without TiSi nanowires.     

Sandwiched Electrochemiluminescent Peptide Biosensor for the Detection of Prognostic Indicator in Early‐Stage Cancer Based on Hollow,Magnetic, and Self‐Enhanced Nanosheets

Currently, peptide‐based protein‐recognition has been recognized as an effective and promising approach for protein assays. However, sandwiched peptide‐based biosensor with high sensitivity and low background has not been proposed before. Herein, a sandwiched electrochemiluminescence (ECL) peptide‐based biosensor is constructed for Cyclin A₂ (CA2), a prognostic indicator in early stage of multiple cancers, based on nanosheets with hollow, magnetic, and ECL self‐enhanced properties. First, hollow and magnetic manganese oxide nanocrystals (H‐Mn₃O₄) are synthesized using triblock copolymeric micelles with core–shell–corona architecture as templates. Then, polyethyleneimine (PEI) and the composite of platinum nanoparticles and tris (4,4′‐dicarboxylicacid‐2,2′‐bipyridyl) ruthenium (II) (PtNPs–Ru) are immobilized on H‐Mn₃O₄ to form H‐Mn₃O₄–PEI–PtNPs–Ru nanocomposite, in which PEI as coreactant can effectively enhance the luminous efficiency and PtNPs as nanochannels can greatly accelerate the electron transfer. Finally, due to the coordination between Eu³⁺ and carboxyl, the obtained H‐Mn₃O₄–PEI–PtNPs–Ru aggregates locally to form sheet‐like nanostructures ((H‐Mn₃O₄–PEI–PtNPs–Ru)_n–Eu³⁺), by which the luminous efficiency is further increased. Based on the nanosheets and two designed peptides, a sandwiched ECL biosensor, using palladium nanocages synthesized through galvanic replacement reaction as substrate, is proposed for CA2 with a linear range from 0.001 to 100 ng mL^?1 and a detection limit of 0.3 pg mL^?1.     

Superconducting YBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>7−δ</Subscript> thick film (T<Subscript>c</Subscript>(0) = 92 K) on a newly developed perovskite ceramic substrate

A complex perovskite oxide, YbBa₂NbO₆, as a non-reacting substrate for YBa₂Cu₃O_7-° super-conducting film has been developed. The dielectric constant and loss factor values of the material are in the range suitable for its use as substrate for microwave applications. A YBa₂Cu₃O_7−δ superconducting thick film dip coated on YbBa₂NbO₆ substrate gave a T_c (0) of 92 K and current density of ∼ 1.3 × 10⁴ A cm⁻².     

Solvothermal synthesis, nanocrystal print and photoelectrochemical properties of CuInS2 thin film

CuInS₂ nanoflakes were synthesized successfully by a convenient solvothermal route in ethylene glycol under the open-air condition using copper chloride, indium chloride and thiourea as starting materials. The factors which might affect the purity of the product during the synthesis were discussed. It's found that the products were significantly affected by the reaction time, temperature and the diffusion of the reactors. CuInS₂ nanoflakes ink was prepared and coated onto Mo substrate using blade technology, and after sintering, a dense and compact CuInS₂ film was produced. The morphological of the precursor films and CuInS₂ films were done by scanning electron microscope (SEM), and the photoelectrochemical properties and morphology of the CuInS₂ thin film were characterized.     

Effects of the type of polycation on the amperometric response of choline biosensors prepared by a layer-by-layer deposition technique

A layer-by-layer deposition technique was employed for fabricating choline biosensors using chloline oxidase (ChOx) and polycations such as poly(ethyleneimine) (PEI) and poly(diallyldimethylammonium chloride) (PDDA). A platinum electrode was coated with ChOx/PEI or ChOx/PDDA thin film to prepare amperometric choline sensors. The amperometric response of the sensors depended significantly on the type of the polycations. The ChOx/PDDA film suppressed the permeation of choline, resulting in a lower response than that of the ChOx/PEI film-based sensors. The results were rationalized based on the different chemical structures of the polycationic materials.     

Electrical, thermal, and mechanical properties of polyarylene ether nitriles/graphite nanosheets nanocomposites prepared by masterbatch route

Graphite nanosheets (GN) reinforced polyarylene ether nitriles (PEN) nanocomposites were successfully fabricated through masterbatch route and investigated for morphological, thermal electrical, mechanical, and rheological properties. The SEM images showed that GN were well coated by phthalonitrile prepolymer (PNP) and dispersed in the PEN matrix. Thermal degradation and heat distortion temperature of PEN/GN nanocomposites increased substantially with the increment of GN content up to 10 wt%. Electrical conductivity of the polymer was dramatically enhanced at low loading level of GN; the electrical percolation of was around 5 wt% of GN. The mechanical properties of the nanocomposites were also investigated and showed significant increase with GN loading. For 10 wt% of GN-reinforced PEN composite, the tensile strength increased by about 18%, the tensile modulus increased by about 30%, the flexural strength increased by about 25%, and the flexural modulus increased by 90%. Rheological properties of the PEN/GN nanocomposites also showed a sudden change with the GN loading content; the percolation threshold was in the range of 3–4 wt% of GN.     

Evaluation of thin film passivation using inorganic Mg-Zn-F heterointerface for polymer light emitting diode

In this study, we manufactured Mg-Zn-F targets using magnesium fluoride (MgF₂) and zinc (Zn). The passivation films were deposited on a poly-ethylenenaphthalate (PEN) substrate using a radio-frequency magnetron sputter. The thickness of the manufactured passivation film was 120 nm. Among the three targets tested, the 4:6 weight target of MgF₂ to Zn resulted in films with the highest Zn content that would increase the packing density of the thin film. The water vapor transmission rate of a 120 nm Mg-Zn-F film prepared from this target and inserted between two 40 nm MgF₂ interlayers on PEN was 2.9 × 10^− 2 g/(m² day) at a relative humidity of 90% and a temperature 38 °C. Its optical transmittance was approximately 80%.     

Production of graphene nanosheets by supercritical CO2 process coupled with micro-jet exfoliation

A facile and cost-effective method which combines supercritical CO₂ and micro-jet exfoliation has been developed for producing graphene nanosheets with high-quality. CO₂ molecules can intercalate into the interlayer of graphite because of their high diffusivity and small molecule size in supercritical operation. The tensile stress induced by graphite interfacial reflection of compressive waves exert on the graphite flakes, which lead to further exfoliation of graphite. Scanning electron microscope (SEM), transmission electron microscope (TEM), atomic force microscopy (AFM), Raman spectrum and X-ray diffraction (XRD) are used to identify morphology and quality of the exfoliated graphene nanosheets, which reveal that the graphite was successfully exfoliated into graphene and more than 88% of graphene nanosheets are less than three layers. The yield of graphene nanosheets is about 28 wt% under optimum conditions, which can be greatly improved by repeated exfoliation of the graphene sediment. The pure graphene film has a high conductivity of 2.1 × 10⁵ S/m.     

AuCl4 ions-assisted fabrication of bimetallic {Poly(ethylenimine)-Ag/Au} multilayer polyelectrolyte film and application in electrocatalysis

Bimetallic {Poly(ethylenimine) (PEI)-Ag/Au} multilayer film was in situ simultaneously fabricated by alternating immersions of a substrate in PEI-Ag⁺ and AuCl₄⁻ solutions followed by chemical reduction with NaBH₄ solution. In the process, the AuCl₄⁻ ions not only play an important role of a reaction reagent, but also served as an assembly reagent. Au, Ag nanoparticles (NPs) were observed with a spherical morphology and well-dispersed in the composite multilayer film, and the size of Au NPs in the bimetallic {PEI-Ag/Au} multilayer film was smaller than that of the single Au NPs formed in {PEI/Au} multilayer films. It was also very interesting to observe that this bimetallic {PEI-Ag/Au} multilayer film exhibited more efficient electrocatalytic activity for the oxidation of ascorbic acid than the multilayer film containing only single Au or Ag NPs. These results indicated that this bimetallic composite multilayer film may be potentially applied in electrochemical biosensors.     

Polyethyleneimine functionalised nanocarbons for the efficient adsorption ofcarbon dioxide with a low temperature of regeneration

Polyethyleneimine (PEI) conjugates with a range of nanocarbons (NCs) have been prepared, and their performances with regard to carbon dioxide absorption and liberation are compared. PEI-functionalised multi-walled carbon nanotubes (PEI-MWNTs) prepared by the reaction of branched PEI (25,000 Da) with F-MWNTs in the presence of pyridine, showed a lower CO₂ capacity at 25 °C (5 wt%, 1.1 mmol CO₂/g adsorbent) as compared to PEI-SWNTs (9.2 wt%, 2.1 mmol CO₂/g adsorbent), consistent with the interior layers of the MWNTs adding weight to the base NC without adding functionality. PEI-functionalised graphite/graphene was prepared by three routes: fluorinated graphite intercalation compounds, prepared from natural graphite powder, were reacted with PEI in EtOH with pyridine; exfoliated natural graphite powder was reacted with Boc–Phe(4-N₃)–OH, and subsequently PEI to give PEI-Phe(4-N-G); graphite oxide (GO) was reacted with PEI in the presence of NEt₃ to give PEI-GO. The CO₂ capacity of PEI-GO at 25 °C (8 wt%, 1.8 mmol CO₂/g adsorbent) was comparable to that of PEI-SWNTs making GO a valid and cheaper alternative to the SWNT scaffold. The temperature of CO₂ desorption of the PEI-NCs was 75 °C, providing a lower energy load for regeneration compared to current amine-based scrubbing units. The rate of CO₂ uptake is seen to depend on the curvature of the NC substrate.     

Effects of different needles and substrates on CuInS2 deposited by electrostatic spray deposition

Copper indium disulphide (CuInS₂) thin films were deposited using the electrostatic spray deposition method. The effects of applied voltage and solution flow rate on the aerosol cone shape, film composition, surface morphology and current conversion were investigated. The effect of aluminium substrates and transparent fluorine doped tin oxide (SnO₂:F) coated glass substrates on the properties of as-deposited CuInS₂ films were analysed. An oxidation process occurs during the deposition onto the metallic substrates which forms an insulating layer between the photoactive film and substrate. The effects of two different spray needles on the properties of the as-deposited films were also studied. The results reveal that the use of a stainless steel needle results in contamination of the film due to the transfer of metal impurities through the spray whilst this is not seen for the glass needle. The films were characterised using a number of different analytical techniques such as X-ray diffraction, scanning electron microscopy, Rutherford back-scattering and secondary ion mass spectroscopy and opto-electronic measurements.     

Super H2O-barrier film using Cat-CVD (HWCVD)-grown SiCN for film-based electronics

“Super H₂O-barrier film” with a water vapor transmission rate (WVTR) less than 1 mg/m²/day has been developed. The barrier layer is a single layer of amorphous SiCN grown by organic Cat-CVD (O-Cat-CVD) with a thickness of 100 nm. SiCN has been grown by using a gas mixture of monomethylsilane (MMS; Si (CH₃)H₃), NH₃ and H₂ on polyethylene-naphthalate (PEN) film substrates. It has been found that the WVTR drastically depends on the W-filament temperature of O-Cat-CVD. The WVTR changed from 5 × 10⁻¹ to 1 × 10⁻³, corresponding to the W-filament temperature increase from 1100 to 1200 C. We have recently succeeded in developing the “super H₂O-barrier film” by the coating of single layers of SiCN for both sides of the PEN film without using the widely used polymer/inorganic multilayer coating. The both-side coating has been found to be crucial to avoid the H₂O penetration into PEN films and also to avoid the breakdown of the SiCN/PEN interface caused by the H₂O accumulation at the interface.     

Redox reaction-assisted growth of ZnO nanowires on SnO2 thin films

ZnO nanowires were grown onto SnO₂ film coated on Si substrate using a vapor transport method. Zn vapor was found to play important roles in reducing SnO₂ and in being oxidized as a ZnO layer. The growth mechanism of ZnO nanowires was revealed to be a two-step process of Zn-SnO₂ redox reaction and Sn catalyzed V-L-S (vapor-liquid-solid) growth; initially, Zn vapor atoms arriving at the SnO₂ surface reduce the SnO₂ to Sn and O atoms and diffuse into the SnO₂ layer to form a ZnO layer. The reduced Sn atoms diffuse out of the SnO₂ layer and are agglomerated to form Sn liquid droplets. Then, the Sn droplets on the surface of ZnO layer serve as a catalyst for the catalytic V-L-S growth of ZnO nanowires.