Multilayer Film Structures Research Articles

Development of multilayer films with improved aroma barrier properties for durian packaging application

The symmetrical A/B/A structure of multilayer blown films was fabricated in this study. The immiscible low‐density polyethylene/polylactic acid (LDPE/PLA) blend was set as a core (B) layer and LDPE was used as skin (A) layers. The compositions of PLA in the core layer were varied from 20 to 50 wt%. The thickness of each layer was 10 μm (total film thickness of ~ 30 μm). In a blown film co‐extrusion process, the morphology of the fiber/ribbon‐like structures of LDPE/PLA blend was developed. Such structures had interesting effects on gas permeability and aroma barrier properties of the films. For instance, multilayer LDPE films containing 40 and 50 wt% PLA (P40 and P50) showed the reduction of oxygen permeability (PO2) approximately 20% and 43%, respectively, compared with the neat LDPE film. A long tortuous path for gas and aroma transportation through film thickness was created from the developed ribbon‐like structures of the PLA minor phase. For durian packaging application, fresh‐cut durian of 300 g was packed in the developed multilayer films, LDPE, and HDPE (Control), stored at 4°C for 7 days. Results demonstrated that the steady‐state condition of 10% to 13% O2 and 8% to 10% CO2 was achieved in all packages except in the HDPE. Moreover, the P40 and P50 films exhibited an outstanding aroma barrier property for three major durian volatiles: diethyl sulfide, ethyl propanoate, and 2‐ethyl‐1‐hexanol. Overall results clearly indicated that the multilayer LDPE films containing PLA exhibited a significantly improved aroma barrier performance with optimum gas permeability desirable for modified atmosphere packaging to retain quality of fresh‐cut durian throughout the storage period.

Chemical Bonding and Electronic Structure in CdS/GO and CdSSe/GO Multilayer Films

The local atomic structure of multilayer films of graphene oxide, cadmium sulfide, and cadmium sulfide–selenide was analyzed by X-ray absorption fine structure spectroscopy. The films were prepared...

Structure and Dynamic Stability of a Multilayer Na Film on the Cu(001) Surface

Mechanisms of atomic layer-by-layer formation of the equilibrium structure of multilayer Na film on the Cu(001) surface have been studied taking into account relaxation and dynamic (phonon) processes. It has been shown that the atomic rearrangement of the substrate-commensurate с(2 × 2) superstructure of the first Na monolayer to a bcc (110)-oriented structure begins with the second monolayer. The dynamic contribution to the formation of the structure of the growing Na film has been estimated. It has been shown that phonon modes select exponentially observed structures from statically favorable structures. All calculations have been performed with interatomic potentials constructed with the embedded atom method. The comparison of the calculated vibrational frequencies with the existing experimental data has demonstrated their good agreement.

Optical Properties of Multilayer BaTiO3/SiO2 Film Structures Formed by the Sol–Gel Method

Multi-layer film structures BaTiO3/SiO2 with a thickness of ~1 μm containing up to 14 pairs of layers were synthesized by the sol–gel method with sequential heat treatment. It is shown that the synthesized structures are X-ray amorphous. The formation of bands in the transmission and reflection spectra caused by interference effects is demonstrated. A more regular structure exhibits a photon band gap (opacity band) in the visible range with main minimum at 636 nm and corresponding maximum in the reflection spectra. Dispersion characteristics of barium titanate films with different concentrations of initial sols were studied and an increase in the refractive index with an increase in the concentration of sol was demonstrated. For a sol with a concentration of 60 mg/mL, the refractive index in the spectral range of 390–1600 nm is 1.88–1.81. The prospects of sol–gel technology for the formation of BaTiO3/SiO2 structures for nanophotonics and solar radiation converters are discussed.

A novel optical ε-near-zero material realized by multi-layered Ag/SiC film structures

The design of novel epsilon-near-zero (ENZ) medium is always the one of focus in electromagnetic field. It is an important and universal method to realize ENZ material by multi-layered isotropic film structures based on the equivalent medium theory. However, the ENZ material designed based on this theory is anisotropic and ε-near-zero is only along a specific direction, which greatly limits its application scope. Therefore, the realization of truly isotropic equivalent ENZ medium is significant for the development of novel optical devices. In this paper, we modify the equivalent medium theory, derive the equivalent parameters formula of multi-layered structure of anisotropic alternating films firstly, and a novel multi-layered Ag/SiC film structures is designed to realize an isotropic equivalent optical ENZ medium based on the above theory. This work perfects the equivalent medium theory system, provides theoretical guidance to improve the design and preparation of optical ENZ material in the future, and the film structure mentioned in this work has also significance for the realization of specific optical ENZ material.

A facile method toward potentially next-generation bacteria detectors using polymer/MWCNT/Au nanocomposite films: a possibility to detecting ability through the shift in resonance frequency

The global market demands for new disposable wireless sensors for food, clinical, tissue, and drug industries in the near future. Gelatin-based multi-layer films were successfully prepared using a room temperature solution casting method. Anticipating future developments, we have looked at the potential applications of cost-effective passive RFID tags in the detection of bacteria (here trypsin was used for biosensing tests) in body fluids, foods, medicines, and much more. This paper is concerned with the measurement of the dielectric constant of materials remotely by using the frequency shift of RFID tags, in the first step. In continue, we establish a setup along with a novel multi-layer structure of gelatin films determining whether there exists any bacterium in a biological fluid or not, by using a physical approach. For this, penetration of bacterium through gelatin multi-layer films causes the RFID tags to be exposed to the biological fluid changing the dielectric constant, detected as a frequency shift. Samples were characterized utilizing FTIR, XRD, TGA, FESEM, tensile, and VNA analyzes. Our proposed wireless biomimetic sensor is able to detect trypsin within a few minutes. The immediate application of our designed biosensor is for the elderly and infants diapers, but further applications in biomedicine, biomedical engineering, food industry, and things like that can be anticipated.

The effect of multilayered film structure on the dielectric properties of composites films based on P(VDF-HFP)/Ni(OH)2

High dielectric constant ceramics fillers are widely used as fillers in polymer matrix to prepare high performance dielectric composites. Homogeneous filler distribution in these composites films is found to be quite difficult to achieve balance between high dielectric constant and high breakdown strength. Herein, multilayer structured composites films containing nickelous hydroxide (Ni(OH)2) as fillers, with different multilayered structures were designed and prepared, including 2–5 layers structure with various filler distribution. The effects of multilayer structure on the dielectric performance are explored by keeping the overall filler content constant. Combined with computer simulation, it is suggested that the variation in filler distribution in these films can effectively redistribute electric field intensity. Meanwhile, the dielectric constant and breakdown strength of the overall composites can be adjusted by changing the volume ratio between high filler content layer and low filler content layer. It is noted that at least 1/3 of the overall film volume should be occupied by a high breakdown strength layer to keep rather high overall breakdown strength. Moreover, high dielectric constant layer should be the outer layers to achieve overall high dielectric constant. Among all the layered structures investigated, the maximum energy density of 6.03 J/cm3 is obtained for film with a 3-layer nonsequential arrangement structure, which is 68% higher than single layer film with identical composition. This study provides some reference value for the preparation of multilayered dielectric polymer composites films for energy storage applications.

Tvrdoća i procena adhezije jednoslojnih i višeslojnih tankih filmova nikla elektrohemijski deponovanih na silicijumskim podlogama sa i bez ultrazvučnog mešanja

Composite systems of monolayer and multilayer nickel films electrochemically deposited on single crystal (100)-oriented silicon wafers were fabricated with and without the ultrasonic agitation. The hardness and adhesion behaviour of these composite structures were characterized by Vickers microindentation test. The dependence of composite microhardness and film adhesion on the structure of the film and mixing conditions of electrolyte were analysed. Mathematical models of Chicot-Lesage and Chen-Gao were applied to experimental data in order to obtain the film hardness and adhesion parameter respectively. It is confirmed that the mechanical properties of composite systems of nickel thin films on silicon substrate can be enhanced by formation of multilayer film structure by ultrasound-assisted electro-deposition and by reducing the layer thickness in the multilayer film.

Optimization of multilayer film structure for hybridization of central receiver system and photovoltaic generation

Optimization of multilayer film structure for hybridization of central receiver system and photovoltaic generation

Electromechanical bending microactuator as optical shutter

This paper presents the design, fabrication methods and characterization of a thin film electromechanical optical shutter. The overlap of the optical channel 1.4 mm high is provided by a multilayer film structure of the cantilever, which profile is determined by the residual internal stresses of the films. In the process of design analysis, the actual parameters of the strained structural layers, the temperature dependence of the curvature, the undamped natural frequencies and the damping parameters of the film cantilever were determined. Correlation of the data shows that the experimental results fit the theoretical data sufficiently closely. The developed control circuit is designed to compensate for the induced dielectric polarization and prevent the control voltage rise and the cantilever sticking effect. The design presented in this publication enables development of a simple and effective electromechanical optical shutter having interruption aperture height which exceeds 1.4mm.

Development of A Comprehensive Biological Hazard‐Proof Packaging Film with Insect‐Repellent, Antibacterial, and Antifungal Activities

A multifunctional film with insect-repellent and antimicrobial activities was developed. Star anise (Illicium verum Hook. f.) oil (SO) proved to be effective in repelling Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) larvae and was selected as an insect-repellent agent. Thymol, a compound that demonstrated strong growth inhibition activities against both Staphylococcus aureus and Penicillium roqueforti, was selected as an antimicrobial agent. Based on the release profile test of SO using various plastic films, polypropylene (30 μm; PP 30) and low-density polyethylene (20 μm; LDPE 20) were selected as laminated films for sustainable insect-repellent and strong antimicrobial effects, respectively. Further, polyethylene terephthalate (12 μm; PET 12) was selected as an intermediate barrier layer. Finally, structure of the multilayer film was designed as PP 30/SO/PET 12/thymol/LDPE 20. The developed film demonstrated insect-repellent activity for >3 weeks, antibacterial activity for >2 weeks, and antifungal activity for 1 week. The results indicated that the developed multilayer film structure possessed strong, sustained insect-repellent and antimicrobial effects, providing a new possibility for the industrial applications to food packaging. PRACTICAL APPLICATION: A multifunctional active packaging film with insect-repellent and antimicrobial activities was developed. Star anise oil and thymol that showed insect-repellent and antimicrobial activities (antibacterial and antifungal activities), respectively, were added in coating layers in the multilayer film structure. The developed multilayer film proved an efficient insect-repellent activity against Plodia interpunctella for >3 weeks. Also, strong antibacterial and antifungal activities of the developed multilayer film were proved against Staphylococcus aureus and Penicillium roqueforti, respectively. The developed film has a potential for the industrial use to the food packaging material.

Formation of a Domain Structure in Multilayer CoPt Films by Magnetic Probe of an Atomic Force Microscope

Abstract—A possibility of changing the magnetic type structure of multilayer CoPt films under action of the magnetic field of the atomic force microscope probe is demonstrated. A new method of non-contact magnetic-force measurements based on artificial increase in the electrostatic interaction between the probe and the film is proposed. This method enables one to controllably change the distance between a probe and a film, thus changing the strength of the magnetic interaction. Using it, one can create from a uniformly magnetized state both a labyrinth domain structure and isolated domains, which are apparently magnetic skyrmions.

Elastic and elastic-plastic analysis of multilayer thin films filled with heterogeneous materials

Due to the mismatch between the coefficients of thermal expansion (CTE) of two adjacent films, the residual stress was growing up during thermal cycling. The aim of this work is to extend the Stoney equation for the multilayer thin films with heterostructure (voids filled with gas or other solids) or unsmooth interface. The general theoretical models were built for elastic and elastic-plastic deformation in the multilayer films with void region filled with other solid or gas. The proposed closed solution (CS) was simplified for analyzing the micro/nano devices with the micromachined multilayered multilayer films structure that thin films locate on a much thicker substrate. One model of through silicon via (TSV) has been built and analyzed. Based on the finite element method (FEM) and the initial CS, a modified CS is built up. The influence of the location and thickness of void, CTE and Young’s modulus (YM) on the normal stress of the thin films was analyzed by the simplified CS and FEM. Based on the FEM and CS the linear and coupled relationship has been set up. With the FEM analysis, the equivalent CTE and YM influenced by the void can be described by equation. The difference of critical temperature for the film from elastic deformation to plastic deformation was studied.

Quality Control of a Multilayer Spin-Tunnel Structure with the Use of a Combination of Analytical Methods

Several experimental methods for controlling the quality of the multilayer film structures used for the fabrication of magnetic tunneling junctions (MTJs) are considered. A multilayer magnetoresistive structure of the following composition is deposited using magnetron sputtering on a Singulus Timaris cluster tool: Ta/CuN/Ta/NiFe/IrMn/CoFe/Ru/CoFeB/MgO/CoFeB/Ta/Ru. A layer-by-layer elemental analysis of the composition of the deposited structure is carried out by the time of flight (TOF) secondary ion mass-spectrometry on a TOF.SIMS 5 installation. A cross section of the structure is analyzed using transmission electron microscopy (TEM) (Tecnai G2 F20 U-TWIN). The crystal structure of the layers is characterized using X-ray diffraction. A comparison of the data obtained using different analytical methods lets us estimate the accuracy of the analysis and the quality of the structure intended for further MTJ fabrication.

Polyelectrolyte complexes of sulfoethyl cellulose–chitosan: effect of the structure on separation properties of multilayer membranes

Membranes of a Simplex type with diffusion layers from sulfoethyl cellulose (SEC) and chitosan were investigated. Aromatic poly (amide imide) (PAI-O) synthesized by the low-temperature polycondensation from dicarboxyphenylphtalimide dichloranhydride and 4,4′-diaminodiphenyl ether was used for the support preparation of the composite membrane. Porous support films with an average pore size in the skin layer of 8 nm, were obtained from PAI-O under conditions of a phase-inversion process. Transport characteristics of membrane samples obtained were tested in processes of the aqueous ethanol pervaporation. All membranes are selective in the isolation of water from 96 wt% ethanol solution. In the case of the SEC layer at the top of composite membrane the selectivity is very high and a water concentration in the permeate reaches 100 wt%. The most selective membranes contained PEC based on counter-ions with the same degree of substitution of hydroxyl groups. The structure and morphological features of multilayer films studied by X-ray diffraction method, scanning electron microscopy and energy-dispersive X-ray microanalysis were discussed in view of a ratio of ionogenic groups of polyelectrolytes and a concentration of their solutions. The boundary of the counterion layers was visualized, as well as the polyelectrolyte complex (PEC). A formation of the PEC layer in the film obtained on a glass plate was shown to occur with the ordering of chitosan chains resulting both hydrated and anhydrous polymorphs, while the formation of the same film on the PAI-O substrate led only to the anhydrous form of chitosan.

The Impact of Nonequilibrium Conditions in Lung Surfactant: Structure and Composition Gradients in Multilamellar Films.

The lipid–protein mixture that covers the lung alveoli, lung surfactant, ensures mechanical robustness and controls gas transport during breathing. Lung surfactant is located at an interface between water-rich tissue and humid, but not fully saturated, air. The resulting humidity difference places the lung surfactant film out of thermodynamic equilibrium, which triggers the buildup of a water gradient. Here, we present a millifluidic method to assemble multilamellar interfacial films from vesicular dispersions of a clinical lung surfactant extract used in replacement therapy. Using small-angle X-ray scattering, infrared, Raman, and optical microscopies, we show that the interfacial film consists of several coexisting lamellar phases displaying a substantial variation in water swelling. This complex phase behavior contrasts to observations made under equilibrium conditions. We demonstrate that this disparity stems from additional lipid and protein gradients originating from differences in their transport properties. Supplementing the extract with cholesterol, to levels similar to the endogenous lung surfactant, dispels this complexity. We observed a homogeneous multilayer structure consisting of a single lamellar phase exhibiting negligible variations in swelling in the water gradient. Our results demonstrate the necessity of considering nonequilibrium thermodynamic conditions to study the structure of lung surfactant multilayer films, which is not accessible in bulk or monolayer studies. Our reconstitution methodology also opens avenues for lung surfactant pharmaceuticals and the understanding of composition, structure, and property relationships at biological air–liquid interfaces.

Al2O3 thin film multilayer structure for application in RRAM devices

This study investigated the effect of resistive switching on Pt/Al2O3/Cu/Al2O3/ITO multilayer structures grown by RF/DC magnetron sputtering. A reproducible unipolar switching free forming was found only for the negative voltage. The SET and RESET processes occurred at very low voltage values, which may be advantageous for practical applications. The ON/OFF ratio was approximately five orders of magnitude for more than 103 s, which is desirable for nonvolatile memories such as resistive random-access memories (RRAMs). We explain the unipolar behavior of the characteristic (I–V) curves in terms of the formation and rupture of conductive filaments, connected via a Cu metal layer.

LASIE: Large Area Spectroscopic Imaging Ellipsometry for Characterizing Multi-Layered Film Structures

In this investigation, we describe a spectroscopic imaging ellipsometry for large area measurements, named as large area spectroscopic ellipsometry (LASIE). LASIE uses a broadband light source and an imaging spectrometer in order to obtain the spectral-spatial intensity images corresponding to a measurement line of a specimen and it can characterize the 3D multi-film structures with the aid of lateral scanning. Opposed to the typical high resolution imaging ellipsometry with the small field of view (FOV), LASIE uses a low magnification imaging lens to enlarge the measurement area and line profiles of multi-layered film structure can be reconstructed at a single operation based on the operation of the spectroscopic imaging spectrometer. In the experiment, 3- and 4-layered film specimen were measured after the system calibration and the 3D film thickness profiles of all film layers were obtained with 1 nm repeatability.

Two-Dimensional Proton Conduction in Biomimetic Polymer Electrolytes Prepared the Polymer Nanosheet Multilayer Film

1．Introduction Organic materials which efficiently transport protons are used in various energy harvesting such as fuel cells and ATP production. Recently, it has been reported that proton transport in the organic materials can be controlled by electric field. [1] In general, protons are transported in two dimension in the protonic transistor, which suggest the importance of fabricating two dimensional proton conductive channel. Biological membrane is a good example for such two dimensional proton conduction. Thus we mimicked the proton conduction at the biological membrane by using polymer nanosheet multilayer film. [2] [3] In this study, we introduce amphoteric group, phosphonic acid to the polymer nanosheet multilayer film. The proton conductivity through the interlayer of the multilayer film was studied by impedance spectroscopy and the mechanism of two dimensional conduction was proposed. 2．Experiment N-dodecylacryamide-co-phosphonic acid copolymers, [p(DDA/VPA)] (Fig. 1) were synthesized by free radical copolymerization of DDA with VPA in ethanol. The monolayer properties of p(DDA/VPA) were investigated by π−A isotherm measurements. The polymer was depositioned on a substrate using the Langmuir-Blodgett (LB) method and film was characterized by X-ray diffraction (XRD) measurement. p(DDA/VPA) was deposited on the substrate with comb-type Au electrode to study the proton conductivity by impedance measurements. 3．Result and discussion The syntheses of p(DDA/VPA) copolymer were confirmed from 1H-NMR and FT-IR. The mole fractions of VPA in the copolymers (n) were determined to be 0.19〜0.52, by elemental analysis. π-A isotherms in all copolymers showed a steep rise in surface pressure and relatively high collapse pressure, indicating that the copolymers formed a densely packed polymer monolayer. The average limiting surface area of VPA suggested that the VPA units were located below the water surface. The lamellar structure of the nanosheet multilayer film prepared using the LB was confirmed by X-ray diffraction measurement. Because the interlayer space increased with n, p(DDA/VPA) formed a multilayer in which a phosphonic acid group is sandwiched between hydrophilic sites (Fig. 2). The proton conductivity parallel to the lamellar plane direction increased with VPA content until n = 0.41 and became 2.6 × 10-2 S cm-1 at 60 ˚C and 98% RH(Fig. 3). Interestingly, the conductivity of n = 0.45 decreased to 1.0×10-2 S cm-1 nevertheless the number of proton source was increased. From the result, we suggest that there is an optimal distance of acid group to achieve a high proton conduction in two dimensional nanospaces. [4] 5．Acknowledgments This work was supported by the Research Program “Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials” within the “Network Joint Research Center for Materials and Devices”. 6．References [1] C. Zhong, et al. Nat. Comm, 2011, 2, 476. [2] T. Sato et al., Langmuir, 2017, 33 (45), 12897–12902. [3] T. Sato et al., Langmuir, 2015, 31 (18), 5174–5180. [4] V. B. P. Leite et al., Phys. Rev. E, 1998, 57, 6835-6839 Figure 1

3D inverse opal nanostructured multilayer films of two-component heterostructure composites: A new-generation synthetic route and potential application as high-performance acetone detector

The preparation of highly ordered porous semiconducting metal oxides (SMOs) films is a hot issue in the field of chemical sensor. Herein, we successfully fabricated 3D inverse opal (IO) ZnO-In2O3 composites multilayer films (MFs) via a novel strategy that combing ultrasonic nebulization deposition technique with polystyrene (PS) spheres template. Such one-step synthetic method is advantageous to achieve the construction of large-scale interconnected macro-porous (pore size: ∼170 nm) structure in composites materials, which is beneficial for facilitating gas molecule transport into the sensing layers and accelerating the surface reactions process. More significantly, by using this method, the large-scale 3D IO MFs made in this work can be easily transferred onto any target substrates without being destroyed. Due to the IO multilayer films structure and abundant heterointerfaces, the 3D IO ZnO-In2O3 MFs-based gas sensor exhibited higher response toward acetone at lower operating temperature, better selectivity and long-term stability, faster recovery speed and lower detection limit. Consequently, the approach described herein is more suitable for the synthesis of porous composites materials films, in order to fabricate high performance chemical sensor.