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Abstract: [Fe/Pt/Cu]18 multilayer films with different Cu thicknesses were prepared on thermally oxidized Si (111) substrates at room temperature using dc- and rf-magnetron sputtering. The magnetic properties and microstructure of [Fe/Pt/Cu]18 multilayer films annealed at various temperatures have been investigated. Compared with pure [Fe/Pt]18 multilayer films low-temperature ordering and (001) orientation in the annealed films with Cu volume concentration below 20% can be obtained. During annealing process Cu atoms diffused into FePt lattice which enhanced the diffusion of Fe and Pt atoms and the grain growth of the films. The perpendicular anisotropy and hard magnetic properties of the films deteriorated with increasing Cu volume concentration due to the formation of L10 FeCuPt2 phase. [Copyright &y& Elsevier]

This article uses the layer-by-layer self-assembly method to fabricate multilayer film on poly(ethylene terephthalate) substrate. The hydrolization of poly(ethylene terephthalate) film was primarily performed with sodium hydroxide aqueous solution to produce a carboxyl-enriched surface. The multilayer films were fabricated by the alternate adsorption of the oppositely charged poly(diallyldimethylammonium chloride) and silver nanoparticles on poly(ethylene terephthalate) substrate. The assembly process was monitored by UV–VIS spectroscopy and inductively coupled plasma. The surface topography and chemical composition of the self-assembly films was characterized by atomic force microscopy and X-ray photoelectron spectroscopy. The images indicated that the silver nanoparticles were successfully assembled and well distributed on the substrate. Furthermore, X-ray photoelectron spectroscopy confirmed the presence of metallic silver on the poly(ethylene terephthalate) substrate. The thermal properties of the multilayer films were investigated by thermogravimetric analysis and dynamic mechanical analyser. The results revealed that the storage modulus of ten-bilayer films decreases with temperature increasing and the glass transition temperature of ten-bilayer films have been found to be 99.3°C, whereas it is 94.8°C for the original poly(ethylene terephthalate) film. [ABSTRACT FROM AUTHOR]

Abstract: The PANI/Pd0 nanocomposite films with Pd nanoparticles embedded in the polyaniline (PANI), were successfully fabricated through the simple layer-by-layer (LBL) adsorption of PANI and PdCl6 2−, followed by the in situ electrochemical reduction of the incorporated PdCl6 2− in the multilayer film. The as-prepared composite films were characterized by X-ray photoelectron spectroscopy, UV–vis spectroscopy, Fourier-transform infrared, atomic force microscope and transmission electron microscopy. The size of Pd nanoparticles in the composite film could be fine-tuned in the range of about 2–22nm by varying the concentration of PdCl6 2−. PANI in the nano-structured PANI/Pd0 composite films still shows the good redox activity in neutral pH solution. The as-obtained PANI/Pd0 nanocomposite film presents an excellent electrocatalytic activity to hydrazine oxidation. And the catalytic performance is not only dependent on film thickness, but also Pd0 size. On the 5-bilayer PANI/Pd0 film with Pd0 particles 2nm in size, two calibration curves were found in the concentration ranges of 3.0×10−7–3.5×10−4 M and 5.0×10−4–1.2×10−2 M. And the minimal detectable concentration was down to 5.0×10−8 M on the electrode with 13 bilayers buildup. The substrate can be used repeatedly for consecutive detection of hydrazine with good stability. [Copyright &y& Elsevier]

Multilayer films for food packaging applications composed of polyvinyl alcohol (PVOH) as the core layer and polyhydroxyalkanoate (PHA) as the outer skin layers were produced by the co-extrusion process. Rheological properties of PVOH and PHA were performed and analyzed before co-extruding into a cast film. Analysis of the rheological data indicated the processing temperatures and grades of the PVOH and PHA polymers that would produce similar viscosity and melt flow properties. To improve adhesion of the layers, PHA was grafted with maleic anhydride using a dicumyl peroxide initiator to provide a tie layer material, which improved the peel strength of the PHA and PVOH layers by over 2×. Oxygen transmission rate (OTR) testing showed that the multilayer sample provided an OTR of 27 cc/m2-day at 0% relative humidity (RH) and rates of 41 and 52 cc/m2-day at relative humidity values of 60% and 90% RH, respectively. This indicates significant barrier performance enhancement over monolayer PVOH that provided an OTR of 60 cc/m2-day at 0% RH and 999 cc/m2-day at 60% RH. Biodegradation testing of the films in the marine environment showed that both the unmodified and maleated PHA polymers displayed high levels of mineralization, whereas the PVOH material did not. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Abstract: This work demonstrates a simple and feasible method to construct magnetic and luminescence nanospheres for drug delivery. Fe3O4@SiO2 core–shell structure nanospheres were firstly prepared, the matrix films capable of loading and release of anionic molecules were then successfully deposited on the surface of the Fe3O4@SiO2 nanospheres via a layer-by-layer (LbL) assembly method by using luminescence microgels (named FITC-PAHD) and chondroitin sulfate (CS) as building blocks and verified by ultraviolet visible and photoluminescence measurements, transmission electron microscopy and fluorescence microscopy. The model drug ibuprofen was loaded into the Fe3O4@SiO2@(FITC-PAHD/CS)4 nanospheres because of the electrostatic interaction of ibuprofen with amine groups in the FITC-PAHD microgels via ion exchange. Ibuprofen loaded in the nanospheres can be released in 0.9% normal saline in a sustainable way for 12days and the Fe3O4@SiO2@(FITC-PAHD/CS)4 nanospheres have a maximum uptake amount of ibuprofen of 117mg·g−1. The magnetic and luminescence nanospheres with high loading capacity are expected to be widely useful as carriers for drug delivery followed by magnetic separation and luminescent detection. [Copyright &y& Elsevier]

The detection of layer-by-layer self-assembly multilayer films was carried out using low-temperature plasma (LTP) mass spectrometry (MS) under ambient conditions. These multilayer films have been prepared on quartz plates through the alternate assembling of oppositely charged 4-aminothiophenol (4-ATP) capped Au particles and thioglycolic acid (TGA) capped Ag particles. An LTP probe was used for direct desorption and ionization of chemical components on the films. Without the complicated sample preparation, the structure information of 4-ATP and TGA on films was studied by LTP-MS. Characteristic ions of 4-ATP (M) and TGA (F), including [M]+•, [M-NH2]+, [M-HCN-H]+, and [F + H]+, [F-H]+, [F-OH]+, [F-COOH]+ were recorded by LTP-MS on the films. However, [M-CS-H]+ and [F-SH]+ could not be observed on the film, which were detected in the neat sample. In addition, the semi-quantitative analysis of chemical components on monolayer film was carried out, and the amounts of 4-ATP and TGA on monolayer surface were 45 ng/mm2 and 54 ng/mm2, respectively. This resulted the ionization efficiencies of 72% for 4-ATP and 54% for TGA. In order to evaluate the reliability of present LTP-MS, the correlations between this approach and some traditional methods, such as UV-vis spectroscopy, atomic force microscope and X-ray photoelectron spectroscopy were studied, which resulted the correlation coefficients of higher than 0.9776. The results indicated that this technique can be used for analyzing the films without any pretreatment, which possesses great potential in the studies of self-assembly multilayer films. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this work, we report on the sensitivity of rheometrical techniques to the nature and size of the interface/interphase in coextruded thermoplastic urethanes (TPUs). In particular, the interphases developed during coextrusion of an amorphous glass (hard) TPU (Isoplast ETPU 301) with one of two elastomeric (soft) TPUs (Estane TPU 58277 and Estane TPU X1175) were studied. Differences in the thickness and nature of the interphase of the two coextruded bilayer films were observed by atomic force microscopy. In one case, the interphase is thicker and rough, and in the other case, it is thinner and flat. Rheology was used in order to probe the type and characteristics of the interphases, with coextruded films having been tested in steady shear, small-amplitude oscillatory shear (SAOS), uniaxial extension, and stress relaxation after a step strain in shear. The results were compared with theoretical predictions assuming zero-thickness interfaces and no interfacial slip. For SAOS and stress relaxation experiments, expressions were deduced in order to enable such a prediction to be made. Of all four rheometrical tests, only stress relaxation after a step shear did not follow the theoretical predictions and, thus, was sensitive enough to detect the presence of the interphase. [ABSTRACT FROM AUTHOR]

Abstract: First a SiO x layer, as a barrier layer between a photo active anatase TiO2 layer and BOPP substrate, was coated on hydroxylated BOPP film by a sol–gel process. Then, TiO2 layer was formed on SiO x surface through liquid phase deposition. Thus a flexible BOPP/SiO x /TiO2 multilayer film which has photocatalytic activity was fabricated. The coating processes were monitored by FT-IR and UV–vis spectroscopy, scanning electron microscopy, atom force microscopy and water contact angle (CA) measurements. The thickness of SiO x and TiO2 layer was about 600nm and 135nm, respectively. Root mean square (RMS) roughness of the SiO x layer was about 2–3nm while the surface of TiO2 layer was much coarse with RMS roughness about 30nm which offered the large surface area. The TiO2 layer endowed multilayer film photoinduced hydrophilic conversion property evidenced by the fact that its surface water contact angle could reduce to about 5° after 1h of UV irradiation. The photocatalytic degradation ability of multilayer film was evaluated using methyl orange as model contamination and the results indicating that the degradation is efficient. [Copyright &y& Elsevier]

Abstract: The uniaxial drawing of PA6/tie/PE multilayer blown films is investigated in relation to the behavior of the pure components. The tensile stress–strain behavior of the multilayers obeys a simple additive mixture law of the one of the components which is consistent with the parallel mechanical coupling of the layer structure of the films. No significant difference is observed in the crystallographic evolution of each layer in the multilayer films as compared with the parent monolayer films. The rupture of the multilayer films yet appears to be directly governed by the PA6 layer, as it triggers an early rupture of the PE layer without decohesion. This contrasts with the rupture behavior upon biaxial drawing that was previously shown to strongly depend on the layer thickness ratio: the thicker the PE layer, the higher the strain at break of both the PE and the PA6 layers. Besides, the strain at break of the PA6 layer in the multilayers under biaxial drawing was greater than that of neat PA6. However, a common feature to uniaxial and biaxial drawing is the similar β–α strain-induced phase transformation and the same limiting value of the α-crystal content at rupture in the PA6 layer, for all multilayer films and the PA6 monolayer film as well. This finding supports the previously proposed rupture criterion based on flaw propagation through the crack-prone α-crystalline phase when this latter phase reaches a critical content for mechanical percolation. The major differences and similarities between the two drawing modes are discussed in consideration of the different state of stress that modifies the pathway of the β–α phase transformation. [Copyright &y& Elsevier]

Abstract: In this paper, ITO/Al/ITO multilayer films are fabricated with the variations of Al film thickness and annealing temperature. The effects of Al film thickness and annealing temperature on sheet resistance, optical transmittance, and the figure of merit are analyzed in the aid of the artificial neural network (NNet) models. In order to verify the fitness of NNet model, the root mean square error (RMSE) of training and testing data are calculated. The NNet models well represent the measured sheet resistance, optical transmittance, and the figure of merit. After NNet model is established, genetic algorithm (GA) is used to find the optimum process condition for the ITO/Al/ITO multilayer films to obtain maximum figure of merit in the design space. [Copyright &y& Elsevier]

Abstract: A key challenge in the preparation of nanoplatelet-filled polymer composites is the ability to realize the nanometer-level dispersion and the planar orientation of nanosheets in polymer matrices. In this report, multilayer films were successfully fabricated by layer-by-layer assembly of regenerated cellulose and graphene oxide, in which graphene oxide nanosheets were used as the building blocks. The thickness of 50 layer film is about 20μm and it exhibits a high degree of smoothness. This may be attributed to the well-defined layered structure with high degree of planar orientation and nanolevel assemblies of graphene oxide nanosheets in the polymer matrices. Typical field emission scanning electron microscope images demonstrate an ordered arrangement of layers. The electrical conductivity of the multilayer films shows a remarkable increase with increasing layer of the films. A significant enhancement of mechanical properties has been achieved, that is, a 110.8% improvement of elastic modulus and a 262.5% increase of hardness respectively. [Copyright &y& Elsevier]

Abstract: The l-cysteine-modified CdSe/CdS/ZnS nanocrystals were synthesized in aqueous solution by using l-cysteine as stabilizer. The chitosan–CdSe/CdS/ZnS ultrathin multilayer films were fabricated on the pretreated quartz substrate by layer-by-layer electrostatic self-assembly method. The CdSe/CdS/ZnS nanocrystals were characterized by X-ray power diffraction (XRD), fluorescence spectrum and UV–vis spectrum. The UV–vis spectrum, fluorescence spectrum, IR spectrum, contact angle analysis and atomic force microscope analysis were used to characterize the chitosan–CdSe/CdS/ZnS ultrathin multilayer films. The results indicate that chitosan and CdSe/CdS/ZnS nanocrystals are alternatively deposited on the quartz surface, resulting in the buildup of a high quality chitosan–CdSe/CdS/ZnS multilayer films. The prepared ultrathin films of chitosan–CdSe/CdS/ZnS show good fluorescent property, which have potential application in biosensor. [Copyright &y& Elsevier]

Abstract: La0.90Dy0.05Nb2O7 nanosheets were achieved by exfoliating a layered compound HLa0.90Dy0.05Nb2O7. Multilayer films composed of the exfoliated nanosheets were prepared by a layer-by-layer deposition technology, which were subsequently heat-treated at 450°C and exposed under ultraviolet light to obtain the polymer-free nanosheet films, respectively. The resulting La0.90Dy0.05Nb2O7 nanosheet suspension and its films exhibit intense emission by the host excitation and negligibly low emission by the direct Dy3+ excitation, whereas the photoluminescence emissions of the bulk precursors are largely dominated by the direct Dy3+ excitation rather than the host excitation. The comparison between the excitation spectra and the bandgap absorption spectra indicates that the enhanced host excitation-mediated photoluminescence of La0.90Dy0.05Nb2O7 nanosheet results from the efficient energy transfer from the O–Dy charge-transfer transition to Dy3+ within the nanosheet, and that the intensive emission of the multilayer films is attributed to the energy transfer from both of the O–Dy charge-transfer transition and the O–Nb network to Dy3+. Dy3+ in the La0.90Dy0.05Nb2O7 nanosheet and the nanosheet-based films gives two emission peaks at around 480 and 576nm and the blue emission is prominent in the film form. [Copyright &y& Elsevier]

Abstract: In order to investigate microwave damping mechanisms of ferromagnetic films with a structure of [ferromagnetic (FM)/non-magnetic insulator (NMI)] n , a serial of [Fe65Co35/SiO2] n multilayer films was prepared by a magnetron sputtering method on the glass substrate. As-prepared films show excellent soft magnetic properties with tiny coercivities along the easy and hard axis respectively, and remarkable in-plane unixial anisotropies were observed too. The microwave properties were characterized by the ferromagnetic resonance (FMR) and a broadband permeameter. The corresponding theoretical fitting was conducted based on the Landau–Lifshitz–Gilbert (LLG) and two magnon scattering (TMS) theory. Fitting results show the TMS linewidth has a value of 36 times bigger than Landau–Lifshitz intrinsic linewidth, which gives a quantitative and explicit physical picture of microwave damping mechanisms in [Fe65Co35/SiO2] n multilayer films and may be important for the understanding of damping in [FM/NMI] n multilayer films. [Copyright &y& Elsevier]

Abstract: Hardness, activation volume and strain-rate sensitivity of Cu/Cr (face-centered cubic (fcc)/body-centered cubic) and Cu/Zr (fcc/hexagonal close-packed) nanostructured multilayer films have been systematically measured as a function of modulation period (L) and modulation ratio (η), respectively. Significant size effects were found for all the three plastic deformation characteristics, i.e. enhanced hardness and activation volume but reduced strain-rate sensitivity with decreasing the dimension length L. Microstructure evolution was statistically examined to rationalize these size dependences. It was crucially observed that abundant nanotwins existed in the Cu grains, though nanotwin formation was depressed with smaller L. This inverse size-dependent nanotwin formation is responsible for the reduction in strain-rate sensitivity, because the negative effect induced by the decreased nanotwins predominates over the positive effect coming from the raised interfaces/boundaries. A mechanistic model is modified to account for the interface effect as well as the nanotwin effect, which yields calculations of strain-rate sensitivity in broad agreement with the experimental results when L is larger than about 20nm. Below this critical length size, there are discrepancies between the calculations and the experimental results, due to the change in deformation mechanism from dislocation nucleation/slip in confined layers to dislocation crossing interfaces. A confined layer slip model is also modified by considering the nanotwin strengthening to quantitatively describe the L-dependent hardness. In addition, the effects of constituent phases and their relative content on the activation volume and strain-rate sensitivity of NMFs are discussed with regard to variation in η. [Copyright &y& Elsevier]

Abstract: The layer-by-layer (LbL) assembled multilayer films are widely used in the biomedical field for the controlled drug delivery. Here, multilayer films were assembled by LbL technique through alternating deposition of poly(diallyldimethylammonium chloride) (PDDA) and poly(acrylic acid) (PAA) on glass slides. Methylene blue (MB) was used as a model drug to investigate the loading and release ability of the multilayer films. The result showed that the loading rate and loading amount of MB were greatly influenced by ionic strength and pH value of the dye solution, and the release rate of MB was also controlled both by ionic strength and pH value of immersing solution. The result also testified that the films had good reversibility of drug loading and release. It suggested that the PDDA/PAA multilayer films had a potential application in drug delivery, especially in drug burst release. [Copyright &y& Elsevier]

Abstract: Multiple twins are experimentally observed within Cu grains in nanostructured Cu/Zr multilayer films. Formation of the multiple twins occurs through the sequential emission of partial dislocations not only from the grain boundaries but also from the Cu/Zr interfaces, which are driven by extremely high internal stresses and highly complex stress state caused by the inhomogeneous microstructures. The multilayers with multiple twins exhibit hardness higher than those with single or coplanar twins, indicative of a significant strengthening effect of the multiple twins. [Copyright &y& Elsevier]

Abstract: In the paper, we report on the layer-by-layer self-assembly of multilayer films of polyelectrolyte/Ag nanoparticles (AgNPs). The films were constructed by the alternate adsorption of the oppositely charged poly [(2-ethyldimethylammonioethyl methacrylate ethyl sulfate)-co-(1-vinylpyrrolidone)] (PQ11) and negatively charged citrate-stabilized AgNPs on solid substrates. The multilayer film growth process on quartz slides was monitored by UV-vis absorption spectroscopy. The resulting films exhibit good catalytic activity toward the reduction of hydrogen peroxide (H2O2). The enzymeless H2O2 sensor based on such films exhibits a fast amperometric response time of less than 5s. The linear detection range is estimated to be from 100μM to 110mM (R 2 =0.996), and the detection limit is estimated to be 78μM at a signal-to-noise ratio of 3. [Copyright &y& Elsevier]

Abstract: The Cu/Ni multilayer films were prepared on the titanium alloy surface by ion-assisted magnetron sputtering deposition (IAD) technique. The Cu/Ni multilayer films could significantly improve the resistance of fretting wear and fretting fatigue (FF) of Ti-811 alloy at room temperature. The FF resistance of the titanium alloy substrate did not increase monotonically with increase in the modulation period thickness of the Cu/Ni multilayer films. The Cu/Ni multilayer films with modulation period thickness of 200nm had the highest FF resistance among the prepared Cu/Ni multilayer films for its comprehensive properties with high toughness, high strength and good lubricating action. [Copyright &y& Elsevier]

Abstract: A sensitive sensor for mercury (II) and copper (II) synchronous detection was established via the changed photoluminescence of CdTe quantum dots (QDs) multilayer films in this work. QDs were deposited on the quartz slides to form QDs-multilayer films by electrostatic interactions with poly(dimethyldiallyl ammonium chloride) (PDDA). Hg2+ or Cu2+ could quench the photoluminescence of the QDs-multilayer films, and glutathione (GSH) was used to remove Hg2+ or Cu2+ from QDs-multilayer films due to strong affinity of GSH-metal ions, which resulted in the recovered photoluminescence of QDs-multilayer films. There are good linear relationships between the metal ions concentration and the photoluminescence intensity of QDs in the quenched and recovered process. It was found that the Stern–Volmer constants for Hg2+ are higher than that for Cu2+. Based on different quenching and recovery constant between Hg2+ and Cu2+, the synchronous detection of Hg2+ and Cu2+ can be achieved. The linear ranges of this assay were obtained from 0.005 to 0.5μM for Hg2+ and from 0.01 to 1μM for Cu2+, respectively. And the artificial water samples were determined by this method with satisfactory results, the recoveries for Hg2+ and Cu2+ ions were found in the range of 90.4–106.4%. To the best of our knowledge, it is the first report about the synchronous detection of Hg2+ and Cu2+ by using quenched and recovered photoluminescence of quantum dots multilayer films. [Copyright &y& Elsevier]

The structural features of the distribution of Pd and Fe atoms in multilayer films derived via Penning-discharge sputtering are studied. The preparation of films is a highly nonequilibrium process; at the same time, it is relatively simple in terms of possible structural implementations, which are shown during the self-organization of sputtered atoms through the formation of clusters with an individual ordered structure. It is important that the 'dynamic chaos' that appears during sputtering is stabilized during crystallization, which makes it possible to study the resulting structures using nondestructive inspection methods with fairly wide possibilities. Therefore, it is of interest to study self-organization during the sputtering of multilayer films in order to reveal the mechanisms of cluster formation and to simulate them. It is also shown that the self-organization during sputtering and subsequent crystallization is accompanied not only by the ordering in the form of clusters, buts also by an ordered arrangement of these clusters. [ABSTRACT FROM AUTHOR]

Abstract: Two kinds of nanocomposite ultrathin films, i.e., (Ag@keratin/PDDA) n and (keratin/PDDA) n +Ag(0) nanoparticles (NP), have been fabricated by layer-by-layer (LbL) deposition and in situ deoxidization method, respectively. The assembling process was monitored by means of UV–vis spectroscopy. Scanning electron microscope (SEM) was used to observe the surface morphology and thickness of the multilayer films. The distribution of silver NP within the two LbL films were evaluated by transmission electron microscope (TEM) measurement. It was found that (Ag@keratin/PDDA) n films present superior fluorescent properties that that of (keratin/PDDA) n +Ag(0) NP. TEM results suggest that the fusion of the small silver clusters (which is fluorescent) is hindered in the direct LbL assembly, while larger Ag NP are formed by the in situ preparation. The corrosion-resistance of the Ag@keratin/PDDA multilayer films against the acid and basic etching solution is also tested. [Copyright &y& Elsevier]

Abstract: In this paper a ZnS/Ag/ZnS (ZAZ) nano-multilayer structure is designed theoretically and optimum thicknesses of ZnS and Ag layers are calculated at 35 and 17nm, respectively. Several conductive transparent ZAZ nano-multilayer films are deposited on a glass substrate at room temperature by thermal evaporation method. Changes in the electrical, structural, and optical properties of samples are investigated with respect to annealing in air at different temperatures. High-quality nano-multilayer films with the sheet resistance of 8Ω/sq and the optical transmittance of 83% at 200°C annealing temperature are obtained. The figure of merit is applied on the ZAZ films and their performance as transparent conductive electrodes are determined. [Copyright &y& Elsevier]

Abstract: The reliability characteristics and thermal conductivity of Ga30Sb70/Sb80Te20 nanocomposite multilayer films were investigated by isothermal resistance and transient thermoreflectance (TTR) measurements, respectively. The crystallization temperature and activation energy for the crystallization can be modulated by varying the layer thickness of Ga30Sb70. A data retention time of ten years of the amorphous state [Ga30Sb70 (3nm)/Sb80Te20 (5nm)]13, [Ga30Sb70 (5nm)/Sb80Te20 (5nm)]10, and [Ga30Sb70 (10nm)/Sb80Te20 (5nm)]7 was estimated when ambient temperature is 137, 163, and 178°C, respectively. Ga30Sb70/Sb80Te20 nanocomposite multilayer films were found to have lower thermal conductivity in both the amorphous and crystalline state compared to Ge2Sb2Te5 film, which will promise lower programming power in the phase-change random access memory. [Copyright &y& Elsevier]

The crystallization temperatures of SiO2/Sb80Te20 nanocomposite multilayer films can be modulated by varying the layer thicknesses of SiO2 and Sb80Te20. The reversible phase transition between amorphous and crystalline states can be achieved by using picosecond laser pulses with different fluences. Compared with conventional Ge2Sb2Te5, SiO2/Sb80Te20 multilayer films possess a faster crystallization speed. The existence of a periodic multilayer structure was confirmed by X-ray reflectivity and transmission electron microscopy characterizations. [ABSTRACT FROM AUTHOR]

Abstract: Au nanoparticles (NPs) were synthesized in the one-pot procedure in water at room temperature with the wheel-shaped VV–VIV mixed-valence tungstovanadate [P8W48O184{V4 VV2 IVO12(H2O)2}2]32− (V12) acting as both reducing and stabilizing agents. The V12 stabilized Au NPs (Au@V12 NPs) were characterized by SEM, TEM, DLS, UV–vis spectroscopy, XPS, and XRD analyses and the negatively charged surface of the Au@V12 NPs was proved by the zeta potential analysis. Based on the layer-by-layer assembly (LbL), the Au@V12 NPs-containing multilayer films have been fabricated on ITO-coated glass slide and quartz substrates with poly(ethyleneimine) (PEI). The regular growth of the multilayer films was monitored by UV–vis spectroscopy and cyclic voltammetry, the composition was characterized by XPS. The Au@V12 NPs based composite films showed electrocatalytic activities towards the reduction of dioxygen and the oxidation of methanol. This approach is expected to open the way towards procedures aimed at the one-step fabrication of Au NPs and polyoxometalates (POMs) into the multilayer films. [Copyright &y& Elsevier]

Abstract: We report on the enhancement in impedance and the break-down behavior of room temperature deposited single and multi-layer metal/oxide films of comparable thicknesses. Aluminum–alumina and chromium–chrome oxide thin film structures grown by sputtering were explored as model systems in this study. Electrochemical impedance spectroscopy measurements showed that the resistance of the structure increases with an increase in the number of metal/oxide bi-layers while the total thickness was kept constant. The resistance of the multi-layer system was over an order of magnitude higher than the single bi-layer for an equivalent total thickness for the case of thin film Al–Al2O3. In addition, potentiodynamic polarization measurements exhibited a consistent and reproducible improvement in the break-down potential with an increase in the number of layers. Similar results are obtained for the case of the chromium–chromium oxide bi-layer system as well. Combination of interfaces and lateral current spreading in the multi-layer structure leads to superior overall break-down resistance suggesting the concept of in-situ sacrificial layers for corrosion protection. [Copyright &y& Elsevier]

Abstract: A glucose-sensitive multilayer film was fabricated by the layer-by-layer (LbL) assembly method with positively charged 21-arm poly[2-(dimethylamino)ethyl methacrylate] (star PDMAEMA) and negatively charged insulin and glucose oxidase (GOD) in the form of {(Star PDMAEMA/Insulin)4 + (Star PDMAEMA/GOD)4 + Star PDMAEMA}. The multilayer film shows an on-off regulation of insulin release in response to stepwise glucose challenge in vitro. It is found that the unique structure of star PDMAEMA and interdiffusion of charged insulin are the main factors to control the on-off status of the film. Reversible surface morphology transitions of the multilayer film were also observed, revealing a phase separation and large-scale reorganization process. Furthermore, the multilayer film could continuously release enough insulin in vivo after being subcutaneously implanted in streptocozotin-induced diabetic rats and reduce the blood glucose level for at least two weeks. It is indicated that such system may have substantial potential as a glucose-sensitive carrier for insulin due to its distinct mechanism. [Copyright &y& Elsevier]

Abstract: A simple mathematical model to predict the oxygen permeability coefficient of multilayer films is presented in this work. Four multilayer systems and the corresponding monolayer films were tested: OPP/OPP (oriented polypropylene), PPcoex/PPcast (co-extruded and casted polypropylene, respectively), PET/PPcast (polyethylenterephthalate and casted polypropylene, respectively) and OPA/OPA/PE (oriented polyamide and polyethylene, respectively). To validate the model, oxygen permeability tests were conducted at 23°C. In particular, the oxygen permeability coefficients of the monolayer films were firstly measured and then used to predict that of the multilayer film. This value was compared with that measured and the percentage error calculated. In the case of the PET/PPcast and OPA/OPA/PE systems, the oxygen barrier properties were measured and predicted at water activity ranging from 0% to 90%. Results showed that the percentage error between the experimental data and the predicted values by the model was close or below to 10% in most of the cases. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the effect of modulation period (Λ) on Ti/TiN multilayer films deposited on high-speed-steel (HSS) substrates using pulse biased arc ion plating is reported. The crystallography structures and cross-sectional morphology of Ti/TiN multilayer films were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM), respectively. Their mechanical properties were determined via nanoindentation measurements, while the film/substrate adhesion via the scratch test. It was found that the highest hardness value reached 43GPa for the modulation period of 54nm, while the film/substrate adhesion also reached the highest value of 83N. Furthermore, the hardness enhancement mechanism in the multilayer films is discussed. [ABSTRACT FROM AUTHOR]

Abstract: The transmission of p-polarized plane wave through Ag/SiO2 multilayer films perforated with periodic subwavelength air slits is investigated by using the finite-difference time-domain (FDTD) method. The results show that the optical transmission property is mediated by the interference among the propagating coupled-SPP modes along the lateral direction inside the SiO2 layers and the conditions of Fabry–Pérot–like resonance along the longitudinal direction together. When some geometric parameters are suitably initialized, the high transmission peaks can split into more peaks as the functional layer (metal/dielectric/metal sandwich stack) number increases, and the wavelength of the same-order transmission peak exhibits a red shift as the grating period increases. [ABSTRACT FROM AUTHOR]

Abstract: The amorphous-to-crystalline transition of Ge/Sb2Te3 nanocomposite multilayer films with various thickness ratios of Ge to Sb2Te3 were investigated by utilizing in situ temperature-dependent film resistance measurements. The crystallization temperature and activation energy for the crystallization of the multilayer films increased with the increase in thickness ratio of Ge to Sb2Te3. The difference in sheet resistance between amorphous and crystalline states could reach as high as 104 Ω/□. The crystallization temperature and activation energy for the crystallization of Ge/Sb2Te3 nanocomposite multilayer films was proved to be larger than that of conventional Ge2Sb2Te5 film, which ensures a better data retention for phase-change random access memory (PCRAM) use. A data retention temperature for 10 years of the amorphous state [Ge (2nm)/Sb2Te3 (3nm)]40 film was estimated to be 165°C. Transmission electron microscopy (TEM) images revealed that Ge/Sb2Te3 nanocomposite multilayer films had layered structures with clear interfaces. [Copyright &y& Elsevier]

Abstract: The shelf life of a food product is largely determined by its chemical and microbiological stability. In this respect, the gas composition surrounding a packaged product plays a major role. Modified Atmosphere Packaging (MAP) is a packaging technique that usually reduces the headspace oxygen to a preferable minimum for most food products. Besides the residual oxygen, the O2-permeability of the packaging material is also important, as it determines the amount of oxygen permeating into the package during storage. This paper describes the development of a practical software simulation tool to predict the amount of oxygen permeating into the headspace during storage for a variety of multilayer packaging configurations. The simulation tool gives access to simulation models for mono- and multilayer films, trays covered with top foils and bottles with caps. The user can compose his/her own (multilayer) packaging material and check the oxygen ingress over time for different temperature conditions for all packaging configurations. Industrial relevance: The software simulation tool is of industrial relevance to food companies, as they can use it to select or compare different films, but also to underpin their choice for a certain packaging material with regard to the sensitivity of the food product to oxygen and the desirable shelf life. The simulation program also provides food companies with information about the influence of storage conditions, like time and temperature, on the ingress of oxygen in their food package throughout the storage-distribution chain. On the other hand, it can also be used by packaging suppliers to predict the oxygen permeability in the optimization process of new films and as a client support tool. [Copyright &y& Elsevier]

Abstract: Depending on the resistivity and transmittance, transparent conductive oxides (TCO) are widely used in thin film optoelectronic devices. Thus doped In2O3 (ITO), ZnO, SnO2 are commercially developed. However, the deposition process of these films need sputtering and/or heating cycle, which has negative effect on the performances of the organic devices due to the sputtering and heat damages. Therefore a thermally evaporable, low resistance, transparent electrode, deposited onto substrates room temperature, has to be developed to overcome these difficulties. For these reasons combination of dielectric materials and metal multilayer has been proposed to achieve high transparent conductive oxides. In this work the different structures probed were: MoO3 (45nm)/Ag (x nm)/MoO3 (37.5nm), with x =5–15nm. The measure of the electrical conductivity of the structures shows that there is a threshold value of the silver thickness: below 10nm the films are semiconductor, from 10nm and above the films are conductor. However, the transmittance of the structures decreases with the silver thickness, therefore the optimum Ag thickness is 10nm. A structure MoO3 (45nm)/Ag (10nm)/MoO3 (37.5nm) resulted with a resistivity of 8×10−5 Ωcm and a transmittance, at around 600nm, of 80%. Such multilayer structure can be used as anode in organic solar cells according to the device anode/CuPc/C60/Alq3/Al. We have already shown that when the anode of the cells is an ITO film the introduction of a thin (3nm) MoO3 layer at the interface anode (ITO)/organic electron donor (CuPc) allows reducing the energy barrier due to the difference between the work function of ITO and the highest occupied molecular orbital of CuPc [1]. This property has been used in the present work to achieve a high hole transfer efficiency between the CuPc and the anode. For comparison MoO3/Ag/MoO3/CuPc/C60/Alq3/Al and ITO/MoO3/CuPc/C60/Alq3/Al solar cells have been deposited in the same run. These devices exhibit efficiency of the same order of magnitude. [Copyright &y& Elsevier]

The magnetic and structural properties of atomic-scale [Fe/Pt]18 and [Fe/Pt/Ag]18 multilayer films annealed at 350 and 400°C have been investigated. The results indicate that, by introducing thin Ag addition layers, the ordering temperature of FePt with nominal 7.4-nm thickness (excluding Ag thickness) can be significantly reduced to 350°C, at which a relatively large coercivity is achieved. When annealing temperature increases to 400°C, the atomic-scale [Fe/Pt]18 and [Fe/Pt/Ag]18 multilayer films show (001) orientation. The reduced diffusion length of atoms in atomic-scale multilayer films and an enhanced atomic diffusion coefficient produced by Ag doping led to the low-temperature ordering and (001) orientation of L10 FePt phase. [ABSTRACT FROM AUTHOR]

Thin multilayer films of alternating ultrathin Ni and Ag layers ( L(Ni)=11,15,30 Å, bulk and $L(\mathrm{Ag})=50~{\AA})$ have been prepared by evaporation in ultrahigh vacuum under controlled conditions and have been studied by the magnetic measurements. The critical temperature TC is studied as a function of the surface exchange interaction ( JS). The dependence of TC on the thickness L of the film has been investigated. A critical value of the surface exchange interaction in the film, above which the surface magnetism appears, is obtained. The shift of the critical temperature TC( L) from the bulk value $[\frac{T_{\mathrm{C}}(\infty )}{T_{\mathrm{C}}(L)}-1]$ can be described by a power law L− λ , where $\lambda =\frac{1}{\nu_{\mathrm{b}}}$ is the inverse of the correlation length’s exponent. The effective critical exponent associated with the magnetization M( β) is deduced for different thicknesses of Ni layers, and the thickness L(Ag) was being kept constant at 50 Å. [ABSTRACT FROM AUTHOR]

Abstract: The degradation undergone by plastic films used for greenhouse coverage is the main cause of the worsening of the processability, of the mechanical properties and of the durability of secondary materials obtained by their recycling. This means that this secondary material cannot be processed to produce films for the same applications (closed-loop recycling). In this work different strategies are proposed to improve the processability, some mechanical properties and the resistance to photo-oxidation of these secondary materials. In particular, homopolymer blends or multilayer films where the secondary material is used in combination with virgin polymer give the best results. [Copyright &y& Elsevier]

Abstract: Light scattering losses from dielectric multilayer are becoming increasingly important for designing high precision performance optical devices. In this paper, we applied the bi-directional reflectance distribution function of optical multilayer and analyzed the total reflectance scattering losses based on both the completely correlated and non-correlated interface models to compare with a high reflection 17-layer optical multilayer deposited on roughness of 2.8nm substrates. The experimental result supports the completely correlated interface model as firstly the wavelength dependence is in good agreement with the phase change of the calculated result and secondly the calculated scattering intensity of the completely correlated interface scattering model is approximately the same as that of the measured scattering spectrum, while the intensity using the non-correlated interface scattering model is significantly higher than the measured result in the high transmission ranges and lower in the main band of the high reflection range. [Copyright &y& Elsevier]

Results of domain structures observation of individual Ni80 Fe20 and Co sublayers in sputter deposited (NIFe/Au/Co/Au)io multilayers, using an element-sensitive method: the photoemission electron microscopy combined with soft X-ray magnetic circular dichroism, are presented. Also, overall domain structures were studied with magnetic force microscopy. The studies allowed us to reveal submicron stripe domains in the investigated samples and the replication of the stripe domains from the Co layers with perpendicular anisotropy to the NiFe layers with easy-plane anisotropy. [ABSTRACT FROM AUTHOR]

Abstract: TiO2/hectorite multilayer films were prepared by the layer-by-layer self-assembly method on glass slides. The quality of multilayer formation was investigated by absorption spectrophotometry, X-ray diffraction (XRD), and electron diffraction (EDS). Evidence was found for the uniform deposition of different components. The increment of film thickness was constant and independent of the number layers deposited. Photocatalytic measurements were made with methylene blue (MB). The kinetic data were represented by the first-order kinetic model. Degradation was continuously monitored by UV-spectrometry. Significant photodegradation of MB was only found in the presence of the multilayer films. [Copyright &y& Elsevier]

Abstract: Polypropylene/high density polyethylene (PP/HDPE) multilayer as well as monolayer films were prepared to develop microporous membranes using cast film extrusion followed by stretching. The effects of draw ratio (DR), cooling air flow rate (AFR), and annealing on the crystalline structure and orientation of the monolayer and components in the multilayer films were investigated using wide angle X-ray diffraction (WAXD) and Fourier transform infrared (FTIR). Annealing and high DR and AFR enhanced the crystal alignments significantly. However, the orientation of the PP and HDPE in the multilayer film was slightly lower compared to the monolayer films. The amount of lamellae formation, long period spacing (L p ), and lamellae thickness (l c ) were obtained via small angle X-ray scattering (SAXS). A significant influence of annealing on L p and l c was observed for the PP. The row-nucleated lamellar crystallization and transcrystallization observed in the surface and cross-section of the films, respectively, are discussed. Scanning electron microscopy (SEM) images of the membrane surface and cross-section obtained for the cold and hot stretch ratios of 55% and 75%, respectively, showed larger pores and higher porosity for the HDPE layer compared to the PP. As the level of the applied extension during cold stretching increased, the water vapor transmission rate (WVTR) of the HDPE monolayer improved while the effect was inversed for the PP single layer. In addition, compared to the monolayer membranes, the multilayer ones showed smaller WVTR. Tensile properties of the precursor films and microporous membranes in the machine and transverse directions (MD and TD, respectively) as well as puncture resistance in the normal direction (ND) were evaluated. [Copyright &y& Elsevier]

Abstract: For a-axis oriented and c-axis in-plane aligned YBa2Cu3O7− δ /artificial pinning center (Y123/APC) alternately-layered thin films, effects of the APC materials on the multilayer structures are discussed. Pr123, (Y1− x Pr x )123 and Gd2CuO4(Gd214) were used as APCs. The multilayer structure was observed for Y123/Pr123 films and Y123/Gd214 films. However, some grains are also grown in the Y123/Gd214 film. For the Y123/Pr123 multilayer film, each Pr123 layer act as two-dimensional APCs (2D APCs) in the magnetic field angular dependences of the critical current density. The growth mechanism of the multilayer structure in the Y123/2D APC films is discussed by a transmission electron microscopy and an atomic force microscope. It is found that two conditions are needed to obtain the c-axis correlated pinning effects by 2D APC in the a-axis oriented and c-axis in-plane aligned Y123/APC multilayer films: the same structure as Y123; Y-free APC materials. [Copyright &y& Elsevier]

Abstract: The layer-by-layer (LbL) adsorption technique allows construction of polyelectrolyte (PE) multilayer films with precisely defined properties and that opens a wide range of applications, where such materials can be used. One of the most important factors governing structure and interfacial properties of polyelectrolyte films is electrolyte concentration and pH of the PE solutions. In the present work we have focused our attention on multilayer films formed using combination of weak polyelectrolytes, PAH/PAA, whose charge can be tuned during the film preparation by pH of their solutions. PE films were formed by LbL technique on silicon wafers, Si/SiO2, and were characterized by ellipsometry, neutron reflectometry and AFM. Additionally quartz crystal microbalance (QCM) was used to determine mass of the films formed on the gold covered QCM crystals. We have found that the thickest films were formed when both polyelectrolytes were weakly charged, while the thinnest films were obtained for fully charged PAH and PAA. However, for the combination of weakly and strongly charged polyelectrolyte the non-monotonic increase of film thickness with a number of deposited PE layers was observed. We hypothesize, that it results from PE reorganization and formation of surface complexes during adsorption of polyelectrolyte layers. [Copyright &y& Elsevier]

Abstract: Stable, monodisperse CdTe quantum dots (QDs) capped with mercaptosuccinic acid were prepared facilely in aqueous medium, which were deposited on the quartz slides to form multilayer films by electrostatic interactions with poly(dimethyldiallyl ammonium chloride) (PDDA). The PDDA/QDs multilayer films are easily fabricated and show high photostability. The fluorescence of the multilayer films could be quenched effectively by Hg (II) ions without obvious shift in maximum photoluminescence emission wavelength, which can be used for the detection of Hg (II) ions. The electron transfer process between the capping ligands and Hg (II) ions should be mainly responsible for the remarkable quenching effect of Hg (II) ions. Under optimal conditions, the quenched fluorescence intensities of multilayer films are perfectly described by modified Stern–Volmer equation with the concentration of Hg (II) ions ranging from 0.01μM to 1μM. [Copyright &y& Elsevier]

The irreversibility temperatures were measured for a-axis oriented and c-axis in-plane aligned Y123/Pr123 multilayer films in various magnetic fields. Pr123 layers act as two-dimensional (planer) c-axis correlated artificial pinning centers (APCs) in the multilayer films. In the irreversibility field -temperature (Birr T) curves, the crossover was observed near matching field Bφ, for the multilayer films, when the magnetic fields were applied parallel to the c-axis of the film (B//c). It is suggested the vortex state in Y123 films with two-dimensional APCs is Bose glass below the crossover field. The Birr T curves under B//a shifted toward lower temperature and magnetic field regions. [ABSTRACT FROM AUTHOR]

The fabrication of an electrode modified with cadmium selenide/methylene blue{CdSe/MB}n multilayer films is introduced via assembling layer-by-layer CdSe and methylene blue on the glassy carbon electrode surface. The multilayer films have been investigated by scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The electrode exhibited a good stability for the simultaneous determination of guanine and adenine in DNA. The experimental parameters were optimized and the limit of detection (S/N = 3) for guanine and adenine was 0.3 ng·mL−1 and 0.9 ng·mL−1, respectively, under the optimum conditions. A direct electrochemical method for simultaneous determination of guanine and adenine in DNA is presented. [ABSTRACT FROM AUTHOR]