Structure Of Films Research Articles

The Impact of Adding Dioxane Derivatives to Polyurethane Structures on their Performance and Degradation in the Environment

AbstractThe novel dioxane-polyether polyurethanes underwent a 12-month outdoor soil burial test to look into how they would degrade in a natural setting. The structure, thermal properties, surface features, and mechanical strength of the polyurethane films were compared. The initial chemical structure and subsequent chemical alterations were identified using FTIR spectroscopy. The polyurethane samples were less thermally stable throughout the duration of the soil burial test, according to TG/DTG curves. According to all findings, polyurethanes containing 1,3-dioxane-5,5-dimethanol exhibit excellent physical characteristics and mild degradation levels after being buried in soil for a year. These polyether urethanes can break down if the rigid domain structure is exposed to moisture and if microorganisms can spread into the polymer matrix. The physical properties, surface features, and degradation of polyether polyurethanes can be improved by varying the molar ratios of the hard segment components and the dioxane derivative structures.

An investigation of the filtration performance and mechanism of oil-solid mixed particles on filter materials with different wettability

In the process of air filtration, filter materials may encounter oil-solid mixed particles from various sources such as industry and household, and the influence of filter material with different wettability on the filtration performance of oil-solid mixed particles has not been fully reported. The objective of this study was to prepare filter materials with varying wettability properties and investigate their filtration performance for oil-solid mixed particles with diverse oil contents. In this study, four filter materials were prepared using the impregnation method, exhibiting 0° (superoleophilic), 46° (oleophilic), 90° and 122° (oleophobic) oil contact angles. The oil-solid mixed particles with varying oil contents were loaded on the four different filter materials. The loading behavior of the filter materials was characterized from two aspects: macroscopic loading behavior (changes in pressure drop and DHC) and microscopic particle deposition behavior. The results demonstrated that, under the conditions of 25% and 50% oil content, the enhanced liquid bridge force between the oil-solid mixed particles on the oleophobic filter material facilitated the formation of a loose and porous cake layer structure compared with other filter materials, resulting in a lower growth rate of pressure drop and a higher dust holding capacity (DHC). However, in 75% and 100% oil content environments, the superoleophilic filter material owned a remarkably high affinity for oil particles compared with other filter materials, leading to the gradual formation of an oil film structure on the filter material, yielding lower the growth rate of pressure drop and higher DHC. These findings shed light on the mechanism of particle deposition under diverse filtration conditions and are applicable to the filtration of various oil-solid mixed particles over a wide range of oil contents.

Largely enhanced Piezoelectric-Fenton capability in rationally designed PVDF/Fe2O3 flexible porous film

The burgeoning piezocatalysts have attracted huge attentions due to their ability to convert natural mechanical energy to degrade water pollutants. However, traditional powder-based piezocatalysts still face an inevitable bottleneck of the secondary pollution because of the diffusion of nanoparticles during the piezocatalysis process. In this work, novel porous polymer-based composite films combining Fenton fillers (α-Fe2O3) and ferroelectric polymer (polyvinylidene fluoride, PVDF) are prepared by rationally designed solution-casted method with a sacrificial “hard template” of table salt. The as-prepared porous PVDF/Fe2O3 film exhibits superior decomposition efficiency of organic pollutants under ultrasonication. Particularly, the easily recyclable porous film with optimized composition and spatial structure offers an ultrahigh rate constant of 0.0498 min−1, which means it can degrade 94.8% rhodamine B (RhB) in 60 min, exceeding that of most reported polymer-based piezocatalysts. Additionally, it has a comprehensive decomposition effect on dyes, antibiotics and natural water with a good cycle performance. The outstanding degradation performance is attributed to the massive hydroxyl radical generated from the enhanced Piezoelectric-Fenton effect, which is ascribed to the synergistic effect of improved piezoelectricity in PVDF, enhanced hydrophilicity and optimized spatial structures in the porous composite films.

Hydrogenated graphene systems: A novel growth and hydrogenation process

Octadecylphosphonic acid self-assembled monolayers were used as a combined carbon and hydrogen source to grow graphene films on sapphire substrates via hot filament chemical vapor deposition. The functionalized substrates were sealed with a thin Cu film and heated to 950°C under Ar flow. After synthesis, the Cu was etched away. The graphene samples then underwent a hydrogenation treatment in the same reactor setup, exposed to a CH4/H2 gas mixture at 820°C for 2 hours. The structure and properties of the graphene films before and after hydrogenation were characterized. Raman spectroscopy was employed to probe the defect-related bands and C-H bonding. X-ray diffraction provided insights into the crystalline structure and interlayer spacing. The ferromagnetic response was measured using a PPMS system across a range of temperatures and magnetic fields. XPS was used to assess the chemical composition and bonding. This multi-step process enabled a detailed evaluation of the novel synthesis protocol and its effects on the resulting hydrogenated graphene material.

Fabrication of chitosan-based fluorescent hydrogel membranes cross-linked with bisbenzaldehyde for efficient selective detection and adsorption of Fe2+

Chitosan, as a natural biomass material, is green, recyclable, sustainable and well biocompatible. The molecular chain is rich in active groups such as amino and hydroxyl groups, and its preparation of fluorescent probes has the advantages of biocompatibility and efficient detection performance. In this study, a bis(benzaldehyde) (BHD) fluorescent functional molecule was designed. Then a series of fluorescent chitosan-based hydrogel films (CSBHD) were prepared using chitosan as raw material and BHD as cross-linking agent. As a fluorescent probe for metal ions, CSBHD was able to efficiently detect Fe2+ with a linear correlation of fluorescence intensity in the range of 0–160 μM, and the limit of detection (LOD) was 0.55 μM. Moreover, it has excellent adsorption performance for Fe2+ ions, with a maximum adsorption capacity of 223.5 g/mg at 500 mg/L Fe2+ concentration. Finally, we characterised the structure and microscopic morphology of CSBHD films and found that CSBHD as a hydrogel film has a high cross-linking density, good water resistance, excellent thermal stability, strong resistance to swelling, and excellent stability in cycling tests. Hence, it has great potential for application in adsorption and detection of Fe2+ ions. It also provides a good strategy for the application of chitosan based fluorescent probe materials in environmental monitoring and heavy metal ion adsorption.

UV-Radiation and TiO2 Nanoparticles Effects on Physical Properties of PVA/CMC/TiO2 Nanocomposite Films

Fabrication of nanocomposite films of polyvinyl alcohol/carboxymethyl cellulose (PVA/CMC) blended with Titanium dioxide nanoparticles (TiO2 NPs) by a modest solution casting technique is investigated. Also, TiO2 NPs and UV-irradiation effects for different intervals (12, 26, 40, and 48 hours) on the morphology (FESEM), structure (XRD), composition (FTIR) and optical properties (UV-Vis) of as-prepared films are inspected. FESEM images display that the morphology of PVA/CMC/TiO2 nanocomposite films is altered due to the strong influence of TiO2 NPs and UV exposure. The XRD spectra indicate that the amorphous phase of the samples has changed (decline or enhancement) due to UV exposure. The FTIR spectra demonstrate that the UV-irradiation period had a favourable impact on polymer structure by exhibiting some interesting IR peaks. Furthermore, the UV-Vis examination illustrates that the increased UV-irradiation times (12 h to 40 h) and TiO2 NPs addition improved the absorption intensity of the as-prepared films. Interestingly, the Energy gap Eg of the nanocomposite films was tuned from 4.47 eV to 5.01 eV with increased irradiation time (12 h to 40 h). In contrast, due to a higher increased UV-irradiation time of 48 h, the Energy gap Eg value of nanocomposite film was decreased to 4.62 eV. That can be attributed to the strong effect of UV exposure, which influenced the creation of structural defects. Finally, these findings prove that the PVA/CMC/TiO2 nanocomposite films have an amazing chance to be used in important optoelectronic applications.

Sustainable Prelithiation Strategy: Enhancing Energy Density and Lifespan with Ultrathin Li‐Mg‐Al Alloy Foil

Sustainable Prelithiation Strategy: Enhancing Energy Density and Lifespan with Ultrathin Li‐Mg‐Al Alloy Foil

Design of CuS composite carbon-based Ni Al-LDH multifunctional phase change composite with electromagnetic shielding performance and heat storage capacity

CuS-based composites are widely used in the fields related to photothermal energy storage and electromagnetic shielding and are excellent candidates for composites with phase change materials. To meet the requirements of micro-integration and electromagnetic resistance of electronic products and optimize the thermal management of electronic products, it is necessary to prepare new flexible composite phase change materials. In this paper, through the design of MPC@Ni Al-LDH/CuS double-layer structure, two-step vacuum filtration method is used, and the highly conductive materials CuS and MPC are introduced into the manufacture of PCM films. With the help of Ni Al-LDH, flame retardancy is introduced. The electromagnetic wave absorption performance is enhanced, and the existence of nano-cellulose (CNF) makes the film have excellent mechanical properties. Ni Al-LDH/MPC and CuS substrates with stable and high mechanical properties are prepared by ultrasonic treatment. According to scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) and thermogravimetry (TG) characterizations, PEG successfully entered the MPC/CuS skeleton by vacuum filtration, and flexible phase change composite bilayers (MLPC) were obtained. Due to the synergistic effect of structure and components, the obtained composite film has many different excellent functions. Specifically, when MPC@Ni Al-LDH is 15 wt%, the phase transition enthalpy, thermal conductivity, electromagnetic shielding, and electrical conductivity are 146.8 J/g, 1.07 W/m·K, 38.8 dB and 126.4 S/m, respectively. The 3600 s infrared temperature measurement results show that the sample has stable thermal properties. Due to the presence of CuS, when MPC@Ni Al-LDH is 5 wt%, its absorbance can be kept at 1.51 L/(g·cm), and its photothermal conversion efficiency can reach 90.6 %. The MPC/CuS structure in the composite film provides many heat transfer channels, which reduces the phonon scattering in the heat transfer process and significantly increases thermal conductivity. Therefore, this multifunctional flexible phase change film can be used in photothermal conversion devices and for thermal management of electronic equipment, and it has broad application prospects in wearable equipment design due to its excellent electromagnetic shielding ability and infrared thermal stealth ability.

A new method for characterizing the atomic composition distribution and interface structure of ultrathin multilayer films using molecular dynamics simulation assisted ARXPS

Characterizing ultrathin multilayer films' atom distribution and interface structure remains challenging. This paper innovatively characterized the chemical composition and distribution of Pt/Co/W ultrathin multilayer films by ARXPS. Molecular dynamics simulated the growth process of films to correspond to that in experiment. The results show that through ARXPS, the actual structure of Pt (2 nm)/Co (t = 0.5–3 nm)/W (2 nm) film could be obtained. For Pt (2 nm)/Co (2 nm)/W (2 nm) film, the actual structure was Pt/Co (1.73 nm)/W (0.78 nm)/WO3 + WO2 (1.48 nm). W at the top layer significantly diffused to the bottom layers, and oxidized W reduced from the surface to the interior of multilayer films. Molecular dynamics simulation confirmed that the interdiffusion degree of Co and W atoms was improved with the increase of Co atoms. The growth modes of Co and W layers were respectively layer-by-layer and island. As the number of Co atoms increased, the relative surface roughness of Co and W layers and the relative interface roughness of Co/W were increased. The in-plane magnetic anisotropy and coercivity were respectively enhanced and decreased due to the change in the surface/interface structure. This paper provides a new idea for analyzing ultrathin multilayer films' atom distribution and interface structure.

Preparation of fluorinated polysiloxane and its application in modified polyacrylates

AbstractPolyacrylate materials are widely used in textile adhesives, functional finishing agents, architectural coatings, and other fields. In order to improve their hydrophobicity and flexibility, a novel fluorinated polysiloxane was prepared by acid catalyzed bulk ring opening reaction with octamethylcyclotetrasiloxane (D4), tetramethyltetravinylcyclotetrasiloxane (), and methyltrifluoropropylcyclotrisiloxane (), and its structure was characterized. Then, as a modified monomer, the fluorinated polysiloxane modified polyacrylates was prepared by miniemulsion polymerization. The effects of fluorinated polysiloxane monomers with different vinyl content and molecular weight on the properties of emulsion, film structure and film hydrophobicity were studied. The results showed that when using fluorinated polysiloxane monomer with Mn = 6235, vinyl content of 0.33 mmol/g, and fluorine content of 7.40 mmol/g for modification, the water contact angle on the surface of the adhesive film reached 100.4°, and the water absorption rate was 8.1%, resulting in the best effect. Used for textile printing, the color fastness to dry and wet friction after fabric printing could reach level 4, and the hand feel was soft.

Tantalum-doped tin oxide thin films using hollow cathode gas flow sputtering technology

SnO2 and tantalum doped SnO2 (TTO) thin films were prepared using reactive hollow cathode gas flow sputtering (GFS) on glass substrates. An in-situ heating process under vacuum preceded the sputtering. The resistivity of the tin oxide films was reduced to a remarkable low of 2.02 × 10−3 Ω cm, with a carrier concentration of 2.55 × 1020 cm−3 and a mobility of 12.11 cm2V−1s−1. As the substrate temperature increased, the film resistivity decreased. Notably, at a substrate temperature of 270 °C, the effect of Ta doping on the film resistivity and carrier concentration was significantly stronger compared to higher temperatures. Elevating the substrate temperature and Ta doping resulted in a lower refractive index (n). This effect was consistently strong at higher temperatures, attributed to the higher film-free carrier concentration (4.54 × 1020 cm−3) compared to lower temperatures (2.35 × 1020 cm−3). The film's structure was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and atomic force microscope (AFM). The preferred direction of film growth was discussed. The successful and reproducible fabrication of tin oxide films underscores the advantages of gas flow sputtering (GFS) technology. GFS offers stable operating conditions across various oxygen flow levels without requiring target oxidization control, as is required in magnetron sputtering when managing gas status and film quality.

Electrospun thermoplastic polyurethane membrane decorated with carbon nanotubes: A platform of flexible strain sensors for human motion monitoring

A piezoresistive flexible strain sensor was developed using thermoplastic polyurethane elastomers (TPU) as the matrix and carbon nanotubes (CNTs) as conductive fillers. Sensitivity, strain range, and tensile cycling stability were concurrently considered during its design. Electrospun TPU fiber membranes were prepared via electrospinning in this experiment, with controllable fiber diameter achieved by adjusting the rotational speed of the electrospinning receiving drum. CNTs were incorporated into a flexible polymer substrate through suction filtration to create the strain sensor. The support structure of the electrospun film served as a carrier for uniformly adhering conductive particles. Well-dispersed conductive CNTs could more easily achieve uniform loading through the pore size of the electrospun fiber film, thereby forming a conductive layer. This study initially determined the influence of TPU content in the spinning solution on the morphology of the electrospun membrane. Subsequently, the effects of CNT content and electrospinning receiving drum rotational speed on the microstructure of TPU electrospun membranes were investigated, along with their impact on the microstructure, mechanical properties, and sensing performance of CNTs/TPU (CT) flexible strain sensors. The results indicate that the electrospun fiber membrane prepared under the conditions of TPU mass fraction of 20 wt% and rotational speed of 100 r/min has a larger average fiber diameter and a more stable scaffold structure. The CNTs/TPU (CT) sensor, prepared by filtering 10 mL of CNTs with a concentration of 2 mg/mL, exhibited the best mechanical properties, with a tensile strength and elongation at break of 6.22 MPa and 575 %, respectively. Additionally, it demonstrated high sensitivity (GF = 420.17 at 200 % strain) and excellent durability stability (300 cycle tests), enabling quick and accurate responses to movements of various parts of the human body, thereby meeting the basic usage requirements of flexible strain sensors.

Influence of synchronized pulse bias on the Microstructure and Properties of CrSiN nano-composite ceramic films deposited by MIS-HiPIMS

In this study, CrSiN nano-composite ceramic films with optimized structure were prepared at low temperature using MIS-HiPIMS technique, owing to improved utilization of the high ionization characteristic of HiPIMS under specially designed synchronized pulsed-bias working mode. The correlations of the synchronized pulsed-bias width, the chemical composition, microstructure evolution, mechanical properties and tribological behaviors were studied systematically. According to the results, the waveforms of the pulsed bias experienced obvious fluctuating periods, indicating fluctuating intensities of positive ions arrived at the substrates. Meanwhile, the fluctuating duration increased with increasing synchronized pulse-width, providing an effective way of adjusting the energetic-ion flux for improved bombardment of the growing film. Therefore, obvious microstructure refinement of the as-deposited CrSiN films had been achieved. Due to optimized ion bombardment, the CrSiN films evolved from a coarse and transgranular columnar structure to a more densified columnar structure with the mixture phases of hcp-Cr2N, fcc-CrN as well as a-Si3N4. Moreover, the hardness and elastic modulus of the CrSiN films were also elevated significantly, to the maximum values of 20.2 GPa and 348.3 GPa, respectively. Furthermore, with the best mechanical properties as well as the highest density, the optimized CrSiN film deposited at 400 μs also displayed the most excellent wear resistance, with the wear rate as low as 9.1 × 10−16 m3/N.m. This study not only proposes a method of optimizing the structure and tribological properties of CrSiN nano-composite ceramic films at relatively low temperature, and also enriches the property database of CrSiN films which could expand their application in fields involving thermal-sensitivity materials.

Porous PbBr2 films modulation by indium tribromide additive for the fabrication of SnO2-based CsPbBr3 perovskite solar cells

The achievement of complete conversion of PbBr2 films presents a significant challenge in the development of CsPbBr3 films with consistent growth, comprehensive coverage, and controllable components. To address this challenge, introducing a porous structure in the planar PbBr2 film is advantageous for facilitating the immersion of CsBr precursor, thereby reducing impurity phase formation and mitigating strain caused by the film volume expansion. In order to accomplish this, indium tribromide (InBr3) was employed as an additive and the InBr3(DMF)3 adduct was utilized to expedite the release of organic molecules in PbBr2(DMF), resulting in the transformation of planar PbBr2 film into porous structures. The growth orientation of PbBr2 crystals was altered by this transformation, effectively suppressing the generation of metallic Pb impurities in the film. Additionally, it not only optimizes the morphology of CsPbBr3 film but also reduces impurity phase. As a result, the InBr3:CsPbBr3 perovskite solar cell achieved an efficiency of 7.28 %. The majority of In3+ ions were concentrated near the buried interface between SnO2 and InBr3:CsPbBr3, leading to significant improvements in both non-radiative recombination defect states within the perovskite film and electron injection and collection capabilities within the device.

Enhancement of remnant polarization in ferroelectric HfO2 thin films induced by mechanical uniaxial tensile strain after the crystallization process

The effect of strain on the ferroelectricity of HfO2 thin films after crystallization was investigated by applying uniaxial mechanical strains to Au/HfO2/TiN metal–ferroelectric–metal (MFM) capacitors. The remnant polarization (2P r) of MFM capacitors increased when tensile strain was applied during polarization switching. This phenomenon should not be attributed to phase transformation from the non-ferroelectric to the ferroelectric phase, taking account of the fast relaxation of 2P r after removal of the mechanical strain and the fact that the crystal structure of HfO2 thin films evaluated by grazing incidence X-ray diffraction measurement was not changed by the tensile strain.

In situ and ex situ investigation on the product films evolution of pipeline steel under AC interference and high cathodic protection conditions

An in situ Raman measurement set-up coupled with AC interference and CP circuits was developed to provide more intuitive detection data for combined action AC and CP corrosion processes. Combined with XPS, AFM and other ex situ surface analyses and electrochemical tests, the evolution of composition, structure and electrochemical properties of surface film is studied. Initially, a passive film is formed on specimen surface, which undergoes successive redox processes. Eventually, the passive film evolves into magnetite and rust, and hydrogen evolution produces mechanical damage to rust layer. Based on this, the model for the evolution of AC corrosion is constructed.

Microstructure evolution and corrosion behavior of TIG welded joint of a new Mg[sbnd]Gd[sbnd]Nd[sbnd]Zn[sbnd]Zr alloy during post-weld heat treatment

The corrosion behavior of the tungsten inert gas (TIG) welded Mg3Nd3Gd0.2Zn0.5Zr alloy with different post-weld heat treatments was systematically investigated. The results show that the corrosion resistance of the sand-cast base material (BM) was inferior to that of the fusion zone (FZ), which was attributed to the larger grain size and exacerbated galvanic corrosion caused by coarser Mg3(Nd, Gd) eutectic phases and numerous β precipitates. It is found that post-weld solid-solution (T4) treatment could significantly enhance the corrosion resistance of the joint due to the dissolution of the cathodic second phases and the denser protective film abundant in RE oxides generated in corrosive solution. The precipitation of nanosized phases and ZnZr clusters would slightly increase the susceptibility to localized corrosion of the peak-aged (T6) joint. As the main corrosion products, MgO and Mg(OH)2 are distributed throughout the whole corrosion film, while RE oxides and RE hydroxides are mainly distributed in the inner layer, which can be explained by inward oxidation and replacement reactions between RE elements and MgO/Mg(OH)2. Based on the composition and structure of the corrosion product film, a physical model has been proposed for depicting the microstructure evolution associated with the corresponding corrosion behavior of the joints. This work could promote the applications of welded MgRE alloy joint in some corrosion environments.

Large anomalous Nernst conductivity of L10-ordered CoPt in CoPt composition-spread thin films

Abstract We demonstrate a high-throughput experimental characterization of anomalous Nernst conductivity (αxy A ) of L10-ordered CoPt using Co1–x Pt x composition-spread thin films on MgO(100) substrates. The compositional dependence of the anomalous Nernst effect (ANE), anomalous Hall effect (AHE) and Seebeck effect is systematically measured. As increasing the Pt concentration, the crystal structure in the composition-spread film grown at 500 °C changes from fcc Co, A1-disordered CoPt, L10-ordered CoPt, A1-CoPt to fcc Pt. The largest αxy A of 2.52 A m–1 K–1 is obtained in L10-CoPt for Pt-rich composition of x = 70%, which is larger than that for an additionally fabricated nearly stoichiometric L10-Co48Pt52 reference uniform film. The contribution from direct conversion of a temperature gradient to a transverse charge current through αxy A is dominant to the total anomalous Nernst coefficient compared to the AHE-related contribution. From a scaling analysis of the AHE, the intrinsic contribution is found to be dominant for x = 70%. A theoretical calculation for αxy A of L10-Co50Pt50 agrees with the experimental αxy A value for the nearly stoichiometric reference film by considering on-site Coulomb interaction for Co atoms. We also point out the possible electron doping effect by the addition of Pt in L10-CoPt, which could explain the larger αxy A for the off-stoichiometric Pt-rich composition than that for the nearly stoichiometric one. Our experimental and theoretical results suggest the potential of L10-CoPt with a large αxy A originating from the intrinsic mechanism for future thermoelectric applications.

The study on the splicing seam of mini‐light‐emitting‐diode display screen

AbstractWhen viewing the mini‐LED display screen from a large angle, the seam appearing at the edge of the module can disrupt the uniformity of the entire screen's bright state. This paper studies the formation mechanism of bright and dark seam and color seam from the perspectives of spatial frequency and packaging structure, derives the formula for spatial frequency, analyzes the optical path at the splicing position, and designs a reasonable packaging film structure to solve the color seam.

Specificity of electrophysical and gas-sensitive properties of nanocomposite ZnO–TiO2 films formed by solid-phase pyrolysis

ZnO–TiO2 thin films containing 0.5 mol%, 1.0 mol%, and 5.0 mol% ZnO were synthesized by oxidative solid-phase pyrolysis. The materials contained anatase and rutile phases with particle size of 6–13 nm, as confirmed using X-ray phase analysis and scanning electron microscopy. When a certain number of ZnO crystallites appeared in the TiO2 film structure in the temperature range of room temperature to 220 °C, a two-level response of the film resistance was observed, differing by approximately 10%, as obtained by electrophysical measurements. The two-level response correlates with the formation of two donor energy levels of 0.28 and 0.33 eV in the band structure of the ZnO–TiO2 films. The donor level with a higher activation energy corresponded to the Ti vacancy (V−Ti), and that with a lower activation energy corresponded to the Zn vacancy (V−Zn). Two levels of gas-sensitive properties were noted for 0.5ZnO–TiO2, 1ZnO–TiO2, and 5ZnO–TiO2 under the influence of 50 ppm NO2 at 250 °C. Such two-level responses can be ascribed to the pinning of the Fermi level on ZnO and TiO2 nanocrystallites. The mechanism of the beak-shaped and two-level responses of sensors based on composite nanomaterials when exposed to various gases was elucidated.