Smooth Film Surface Research Articles

Significant impact of melt-blend and hot-press technique operating condition on polyethylene/thermoplastic starch/aloe vera gel film properties

Melt-blend and hot-press techniques were among the most popular methods for producing polyethylene/thermoplastic starch (PE/TPS) polymer blends. However, different operating conditions contributed to the various quality of film made. Thus, this paper focuses on determining the most suitable operating conditions involving melt-blend and hot-press techniques on specific PE/TPS/aloe vera gel (AV) film formulations. Thus, this study determines the best operating condition for producing PE/TPS/AV blend. One-factor-at-a-time (OFAT) method was implemented under six operating conditions: different melt-blending temperatures, pre-heating, hot-pressing pressure, temperature and duration, and cooling application. The result demonstrated that the best melt-blending temperature was 170 °C, having the highest tensile strength (TS) performance. Pre-heating application reduced the thickness, which is suitable for applying single-used plastic and more economical than thicker film. Importantly, this study found the lowest pressure to obtain a smooth surface of film without stickiness during the peeling process from the steel plate after applying the hot-press technique. The same condition faced at 130 °C, hot-pressing temperature produced a smooth and clear film structure. The pro-longed hot-pressing duration reduced the bonding strength of the polymer matrix. Finally, a fast-cooling rate enhances the TS of the film. Therefore, the melt-blending and hot-pressing operating conditions significantly impact the physical and mechanical properties of PE/TPS/AV film. The results of this study are valuable for understanding that each formulation needs a specific processing condition essential as an initial assumption in simulation processes.

Solution-processed Er3+-Doped GeS2 chalcogenide glass films with NIR photoluminescence towards functional flexibility and integration.

Rare-earth doped chalcogenide films are major components in flexible and integrated photonic and optoelectronic devices for modern communication systems, metrology, and optical sensing. However, it is still challenging to develop a high concentration of rare-earth doping chalcogenide film with a smooth surface to realize efficient photoluminescence (PL). Here, we demonstrate that Er3+-doped GeS2 films are prepared by spin-coating based on a two-step dissolution process. Such a two-step process provides the high solubility of Er3+ in GeS2 films and exhibits efficient emission at ∼1.5 µm crossing the telecommunication C-band. The highest PL emission intensity is obtained in GeS2 films doped with 1.4 mol% of Er3+, and this PL in GeS2 films is reported for the first time. We propose adjustments of annealing parameters for improving the PL characteristics in such materials. Through the control precision of the heating rate and annealing temperature, the smooth surface of GeS2 films enables efficient photo-luminescence. This two-step dissolution-based strategy would pave a new path to design luminescent chalcogenide films for application in flexible and integrated optoelectronics and photonics.

One-Step Fabrication Bioinspired Flexible Hierarchical Micro-Nano Structures with Different Morphologies.

In this study, different flexible structures that are morphologically like the micro-nano pillars, setae, and cilia on many natural organism surfaces are created with a novel fabricating strategy to explore the phenomenon and mechanism of static and dynamic droplets forming on them. Just by adjusting the mold pattern during fabrication, different micro/nanomorphologies including micro-nano pillar, filament, or flake arrays could be conveniently obtained on a pristine smooth film surface. Due to the existence of uniformly distributed hierarchical micro-nano structure arrays that are composed of top-down nanoscale filamentous tips, micro block bases, and grooves on the film, air trapped in arrays connects the atmosphere continuously and forms a successive air-pocket layer, which greatly reduces the solid-liquid interfacial fraction and endows the micro-nanotextured film with the capability of superhydrophobicity, low-adhesion, self-cleaning, anti-icing, and deicing characteristics. Through various mechanical and chemical tests, the film has demonstrated its robustness, making it highly suitable for a wide range of practical engineering applications.

Characterization of Nano-SiO2/Zein Film Prepared Using Ultrasonic Treatment and the Ability of the Prepared Film to Resist Different Storage Environments.

This study has developed, ultrasound-assisted, a novel food packaging film (U-zein/SiO2) for food packaging applications. Incorporating an optimal concentration of 18 mg/mL of nano-SiO2 and subjecting the film to 10 min of ultrasonic treatment resulted in a remarkable increase of 32.89% in elongation at break and 55.86% in tensile strength. In addition, the incorporation of nano-SiO2 effectively reduces the water content and solubility of the composite film, resulting in improved water/oxygen barrier properties. These physiochemical properties were further improved with the application of ultrasound. The analysis of attenuated total reflectance-Fourier transform infrared, X-ray diffraction, differential scanning calorimetry, and scanning electronic microscope demonstrated that the ultrasound treatment improved the hydrogen bonds, improved thermal stability, molecular arrangement, structure stability, and intermolecular compatibility of the composite film, resulting in enhanced physio-mechanical properties of the film. In addition, the ultrasound treatment led to a smoother film surface and reduced the pores on the film's cross-section. Moreover, the U-zein/SiO2 film exhibited excellent mechanical and water/oxygen barrier properties in different storage environments over a period of 30 days. These results offer sound theoretical support for the practical application of the prepared preservative film.

Construction of Al-BTA passivation film on the surface of electrolytic copper foil and study of corrosion resistance mechanism

The use of chromates in copper foil metal passivation is becoming increasingly limited due to the emphasis on green production concepts. Thus, it is important to develop a chromium-free passivate that is both environmentally friendly and sustainable. Al(OH)3 passivation films were constructed on the surface of electrolytic copper foils by a simple impregnation method using NaAlO2 as the passivator, and it was found that the addition of a small amount of 1,2,3-benzene propyl triazole (BTA) could significantly improve the corrosion resistance of the passivation film. The passivation mechanism of the composite passivation film was investigated by electrochemical and related characterization tests. The results indicated that the self-corrosion current density (icorr) of the Al-BTA composite passivation film was reduced by two orders of magnitude to 4.375 × 10−7 A/cm2 compared to bare copper, which was better than that of the single aluminum-based passivation film at 5.562 × 10−6 A/cm2. In addition, the smooth and dense surface of the Al-BTA composite passivation film effectively blocked the erosion of corrosive media and protected the copper foil substrate, which has certain prospects for industrial applications.

High-performance ultraviolet Cs3Cu2I5 photodetector derived from two-step annealing process

Perovskite based ultraviolet photodetectors have great potential in fire warning, disease treatment and missile guidance, etc. owing to its high mobility, large absorption coefficient and solution processability. However, poor stability and toxic lead element hinder it further applications in current stage. Recently, all-inorganic lead-free perovskite Cs3Cu2I5 demonstrates great potential in ultraviolet detection for its outstanding long-term stability and suitable bandgap. Nevertheless, pinholes and roughness of film lead to leakage current and lower carrier mobility, restricting detection performance. Herein, a two-step annealing method was introduced to optimize the nucleation and crystallization of Cs3Cu2I5 grains. Owing to the improvement of grain quality, fewer pinholes and precipitated phases occurred during crystallization process, thus, resulting in compact and smooth film surface. The hole and electron mobilities of the two-step annealed film were promoted up to 0.697 cm2/(V·s) and 1.579 cm2/(V·s) respectively. As a consequence, the constructed Cs3Cu2I5 photodetector exhibits high on/off ratio of 6.3 × 104, a shorter response time of 26.2 ms (τrise)/49.9 ms (τfall), external quantum efficiency of 3.04%, moderate responsivity of 8.46 mA/W and detectivity of 3 × 1013 Jones. Basing on these merits, an ultraviolet imaging was demonstrated. This work provides an effective but simple strategy to endow Cs3Cu2I5 photodetector with improved performance for further applications in the future.

Impact of metal doping on the physical characteristics of anatase titanium dioxide (TiO2) films

This study focuses on the synthesis of anatase titanium dioxide (TiO2) films doped with metals (Mg, Ni, and Sn) using the sol–gel dip coating technique. The main objective was to investigate the chemical, crystal, and morphological structure of the Mg-, Ni-, and Sn-doped TiO2 films. The doping mechanism between the metals and the TiO2 films was confirmed through Fourier-transform infrared (FTIR) spectroscopy, which revealed characteristic absorption bands associated with the doping process. Additionally, X-ray diffraction (XRD) patterns confirmed that all films maintained an anatase phase, indicating the preservation of the desired crystal structure. Furthermore, the introduction of Mg and Sn metals into the TiO2 film resulted in a decrease in the crystallite size, reducing it from 53 to 16 nm and 24 nm, respectively. Conversely, the incorporation of Ni into the TiO2 film increased the crystallite size to 72 nm. Moreover, the presence of these metals in the TiO2 film contributed to a smoother film surface, thereby enhancing the hydrophilicity of the films. The optical bandgap of the TiO2 films decreased with the introduction of Mg, Ni, and Sn, exhibiting values of 3.24 eV, 3.11 eV, and 3.15 eV, respectively, compared to the original value of 3.33 eV. Additionally, the electrical conductivity (σ-value) increased upon the introduction of Mg, Ni, and Sn, reaching values of 0.25 mS.cm−1, 0.37 mS.cm−1, and 2.5 mS.cm−1, respectively. Overall, this work provides insights into the chemical, crystal, and morphological characteristics of Mg-, Ni-, and Sn-doped TiO2 films.

Enhancing Photovoltaic Performance and Stability of Perovskite Solar Cells through Single-Source Evaporation and CsPbBr3 Quantum Dots Incorporation

This study investigates the potential of inorganic perovskite CsPbBr3 as a photovoltaic material, highlighting its superior stability compared to that of organic–inorganic hybrid perovskite materials. Conventional methods for preparing CsPbBr3 perovskite films, such as the two-step method and the dual-source thermal evaporation method, face challenges in obtaining high-purity films due to the decomposition of precursor films and the formation of multiple heterogeneous phases. To address this issue, we synthesized CsPbBr3 powder material using thermal evaporation deposition, which effectively suppressed decomposition and the formation of heterogeneous phases. Consequently, we achieved uniform and dense CsPbBr3 perovskite films. By incorporating energy-band engineering modification with CsPbBr3 quantum dots (QDs), the all-inorganic perovskite solar cells (PSCs) attained a power conversion efficiency (PCE) of 7.01% under standard solar illumination conditions. The device PCE remained at 93% of its initial efficiency under 30% relative humidity conditions for over 100 days, showcasing its durability. The developed method produced an average grain size of 800 nm, resulting in a smooth and uniform film surface, thereby demonstrating the method’s high repeatability. Additionally, the optimized PSCs exhibited a high open-circuit voltage (VOC) with the champion device reaching a VOC of 1.38 V and a PCE of 7.01%. This research presents a robust, efficient, and cost-effective approach for fabricating high-quality all-inorganic PSCs.

Uncovering solvent-engineering mechanisms in Y6:PM6 solar cells

Additives, like 1-chloronaphtalene (CN), are commonly used in Y6:PM6 solar cells as they lead to an increased power conversion efficiency. In this work, we investigate the influence of CN during spin coating of Y6:PM6 dissolved in chloroform via an in situ transmission setup. We show that, in the presence of CN, the film formation of Y6:PM6 can be divided into two parts: one related to the evaporation of chloroform and one related to the evaporation of CN. This is mostly related to Y6 being dissolved in CN. We find that even for low CN concentration, the film formation is not completed for several minutes after the spin coating process. Furthermore, the removal of CN is needed to achieve a smooth film surface. We demonstrate that this fast removal can be achieved by spin coating the electron transport layer PDINN from methanol. The methanol is acting as an anti-solvent for the CN, leading to its removal from the film. Using this approach, solar cells fabricated with a high CN concentration of 5% feature a comparable performance to ones with more common concentrations between 0.5% and 1%.

Potential use of propolis-loaded quaternized chitosan/pectin hydrogel films as wound dressings: Preparation, characterization, antibacterial evaluation, and in vitro healing assay

Quaternized chitosan (QCS) was blended with pectin (Pec) to improve water solubility and antibacterial activity of the hydrogel films. Propolis was also loaded into hydrogel films to improve wound healing ability. Therefore, the aim of this study was to fabricate and characterize the propolis-loaded QCS/Pec hydrogel films for use as wound dressing materials. The morphology, mechanical properties, adhesiveness, water swelling, weight loss, release profiles, and biological activities of the hydrogel films were investigated. Scanning Electron Microscope (SEM) investigation indicated a homogenous smooth surface of the hydrogel films. The blending of QCS and Pec increased tensile strength of the hydrogel films. Moreover, the blending of QCS and Pec improved the stability of the hydrogel films in the medium and controlled the release characteristics of propolis from the hydrogel films. The antioxidant activity of the released propolis from the propolis-loaded hydrogel films was ∼21–36 %. The propolis-loaded QCS/Pec hydrogel films showed the bacterial growth inhibition, especially against S. aureus and S. pyogenes. The propolis-loaded hydrogel films were non-toxicity to mouse fibroblast cell line (NCTC clone 929) and supported the wound closure. Therefore, the propolis-loaded QCS/Pec hydrogel films might be good candidates for use as wound dressing materials.

Synthesis and characterization of chitosan/cellulose blend reinforced with copper oxide nanoparticles as moisture barrier film

Bio-based plastics emerged as eco-friendly and resource-efficient substitutes for petroleum-based counterparts. Despite the continuous efforts to develop these alternatives, their inferior performance, most notably mechanical and moisture barrier aspects, limits their application. Material hybridization, like polymer blending and nanocomposite technology, are among the methods employed to improve the properties of bioplastics. This present work focuses on synthesizing bioplastic films with 30/70, 50/50, and 70/30 chitosan to cellulose (CH/CE) percent weight ratios. FTIR analysis of the blend films revealed interaction between NH2 and OH, confirming the compatibility between chitosan and cellulose. Analysis of variance showed increasing cellulose content significantly (p < 0.05) enhanced the resistance to swelling. The 30/70-CH/CE film exhibited the least swelling, which is 65.5% lower than the pure chitosan film. Moreover, copper oxide nanoparticles (CuO NPs) were prepared as reinforcement due to its hydrophobicity. Structural and morphological analyses of hydrothermally synthesized CuO nanoparticles confirmed monoclinic and urchin-like structure. Varying amounts of CuO NPs, i.e., 1%, 3%, and 5% w/v were added to the 30/70-CH/CE films to further enhance the moisture barrier properties. The best barrier performance was attained at 5% w/v, indicated by the smallest % swelling (93.25%) and largest contact angle measurement (89.32°). This could be related to the morphological change from fibrous to smoother film surface with increasing amount of CuO NPs. Results suggest the potential of the chitosan/cellulose polymer blend and the copper oxide nanoparticle-reinforced films for moisture barrier applications.

Interactions of Catalytic Enzymes with n-Type Polymers for High-Performance Metabolite Sensors.

The tight regulation of the glucose concentration in the body is crucial for balanced physiological function. We developed an electrochemical transistor comprising an n-type conjugated polymer film in contact with a catalytic enzyme for sensitive and selective glucose detection in bodily fluids. Despite the promise of these sensors, the property of the polymer that led to such high performance has remained unknown, with charge transport being the only characteristic under focus. Here, we studied the impact of the polymer chemical structure on film surface properties and enzyme adsorption behavior using a combination of physiochemical characterization methods and correlated our findings with the resulting sensor performance. We developed five n-type polymers bearing the same backbone with side chains differing in polarity and charge. We found that the nature of the side chains modulated the film surface properties, dictating the extent of interactions between the enzyme and the polymer film. Quartz crystal microbalance with dissipation monitoring studies showed that hydrophobic surfaces retained more enzymes in a densely packed arrangement, while hydrophilic surfaces captured fewer enzymes in a flattened conformation. X-ray photoelectron spectroscopy analysis of the surfaces revealed strong interactions of the enzyme with the glycolated side chains of the polymers, which improved for linear side chains compared to those for branched ones. We probed the alterations in the enzyme structure upon adsorption using circular dichroism, which suggested protein denaturation on hydrophobic surfaces. Our study concludes that a negatively charged, smooth, and hydrophilic film surface provides the best environment for enzyme adsorption with desired mass and conformation, maximizing the sensor performance. This knowledge will guide synthetic work aiming to establish close interactions between proteins and electronic materials, which is crucial for developing high-performance enzymatic metabolite biosensors and biocatalytic charge-conversion devices.

Large ammonium cation-induced controlled mixed-phase of CsPbBr3 perovskites for color tunable perovskite light-emitting diodes

Color tunability is a unique advantage of perovskite light-emitters for next-generation display technologies because controlled dimension and phase of metal halide perovskites can vary the optoelectronic properties of perovskite light-emitting diodes (PeLEDs). Herein, we demonstrate a color tuning of green-emitting CsPbBr3–based PeLEDs to sky-blue by employing n-butylammonium bromide (BABr). The incorporation of BABr, a large ammonium cation, in CsPbBr3 facilitates the formation of 2-dimensional (2D) perovskite structure with band-gap widening that corresponds to fluorescence peak shift from 513 to 406 nm. In addition, the incorporation of BABr is found to restrict the quick nucleation and rapid growth of CsPbBr3 crystals to allow subsequent growth of 2D structure with lower n-phases, affording a smooth and uniform film surface. As a result, the optoelectronic properties of the CsPbBr3-based PeLEDs were significantly improved by BABr with a brightness of 5260 cd m–2, peak external quantum efficiency of 6.72 % and a maximum current efficiency of 27.78 cd A–1. Moreover, the BABr addition also induced a facile color conversion from green to sky-blue, suggesting remarkable potential toward high-performance PeLEDs with tunable emission colors for next-generation display technologies.

Effect of polyvinyl alcohol to starch ratio on the nutrient release and water absorption behaviour of slow release fertiliser

In the present study, polyvinyl alcohol (PVA) has been blended with starch to confine the fertiliser particles in the polymer matrix. NPK fertiliser particles have been embedded in polymer matrix by a solution casting method. Different weight ratios of PVA to starch, that are 7:3, 5:5 and 3:7 have been investigated. Morphologies of the samples have been studied using optical microscopy. Higher content of PVA in composition leads to a smooth surface of film. The prepared samples have been characterised by ionic conductivity measurements and water absorption tests to estimate the fertiliser release rate and water retention capacity, respectively. Sample containing higher content of PVA shows lower change in ionic conductivity and hence, lower release of nutrients in 24 h of soaking in distilled water. Among the three samples, composition having PVA to starch ratio of 5:5 shows uniform surface, higher water retention characteristics and thereby, better slow release capabilities.

Influence of the cooling rate in annealing post-treatment on small molecule with siloxane side chains for solution-processed organic field-effect transistors

In this study, a donor-acceptor-type small molecule possessing a narrow bandgap with siloxane-terminated side chains, namely, S-LBG, was synthesized and characterized to be used as a semiconducting layer in organic field-effect transistors (OFETs). The diketopyrrolopyrrole (DPP)-based small molecule contains silaindacenodithiophene as an electron-donor core and 2-(1,1-dicyanomethylene)rhodanine as an electron-accepting end group. S-LBG films show highly crystalline structures after thermal annealing treatment owing to the strong intermolecular interactions between its siloxane side chains; furthermore, a smooth-surface film with a large polycrystalline grain size can be fabricated by controlling the cooling rate after annealing. Solution-processed OFETs using cooled S-LBG films at a rate of 1 °C/min and exhibits a high hole mobility of 0.102 cm2 V−1 s−1 with a π–π stacking distance of 0.659 nm.

Production and characterization of biodegradable bi-layer films from poly(lactic) acid and zein

Recently, packaging industry has turned to biodegradable packaging, and poly(lactic acid) has become the most remarkable polymer. However, the high oxygen permeability of PLA films significantly limits their use. Therefore, this study, it was aimed to improve the oxygen barrier properties of PLA films without adversely affecting the mechanical and water vapor barrier properties. Biodegradable PLA-Zein bi-layer films were produced by changing PLA and zein thickness. Transparent and UV barrier bi-layer films were obtained. Mechanical properties of PLA films were improved by the production of bi-layer films. Water vapor permeability of bi-layer films increased whereas the permeance decreased with zein coating of PLA. Multi-criteria decision hierarchy was used to select the best bi-layer films based on mechanical, permeance, and opacity results. Oxygen barrier properties of PLA film significantly improved by zein coating, and hydrophobicity of PLA film was not affected by zein coating. The crystallization and melting temperatures of films decreased when compared to PLA films, supporting the mechanical results. Homogeneous, non-porous, and smooth film surface was obtained and zein layer was in good compatibility with PLA layer. These results suggest that zein coatings could be used to decrease oxygen permeability of PLA films without negatively affecting other properties.

Effect of Annealing Temperature on the Structural, Optical, and Electrical Properties of Al-Doped ZrO2 Gate Dielectric Films Treated by the Sol–Gel Method

In this article, we report the preparation of Al-doped ZrO2 (AZO) thin films by the sol–gel method. The electrical properties, microstructure, and optical properties of AZO high-k gate dielectric films at different annealing temperatures were systematically investigated. XRD results confirm that the AZO film was amorphous at a temperature of 600 °C, and Al doping raises the crystallization temperature of ZrO2. AFM and FESEM show a smooth surface of AZO film without cracks. As the annealing temperature increased from 600 to 900 °C, all of the films had similar RMS roughness under 1 nm, the film thickness decreased accordingly, the bandgap value increased from 5.77 to 5.82 eV, the valence band shift (ΔEv) increased, and the conduction band shift (ΔEc) decreased. XPS analysis showed that silicates were formed at the AZO/Si interfacial layer. Electrical performance tests showed that high-temperature annealing can effectively improve the electrical properties, as shown by the increase in dielectric constant (k) and the decrease in flat-band voltage (ΔVfb). However, an increase in leakage current density with increasing annealing temperature was observed due to the decrease in ΔEc and the appearance of crystallization caused by the increase in annealing temperature.

Air entrainment dynamics of aqueous polymeric droplets from dilute to semidilute unentangled regimes

Recent studies have revealed the air-cushioning effect of droplet impact upon various surfaces and although pure water droplets have extensively been studied, the air entrainment dynamics for aqueous polymeric droplets was the focus of this study. Herein, droplets of low to moderate Weber numbers, We ∼ O(1−10), displayed air film thickness gradients which was strongly influenced by the viscoelastic properties of the aqueous polymeric droplets in the dilute to the semidilute unentangled regimes. Aqueous polyethylene oxide droplets impacting a smooth thin oil film surface formed a submicrometer air layer, moments prior to impact, which was tracked by a high-speed total internal reflection microscopy technique. The radial changes in the air film thickness were related to the polymer concentration, thus providing an alternative tool for comparing the rheometer-derived overlap concentrations with a contactless optical technique.

Evaluating surface smoothness of composite film of well-dispersed silica particles

ABSTRACT The surface smoothness of a composite film of polyimide and silica particles was evaluated by changing the dielectric constant based on the gap between the film surface and electrode surface. The silica particles were modified by different treatments, then mixed with the polyimide to prepare the particle composite films. The experimental results showed that even in the films with well-dispersed particles, a more suitable dispersion state exists based on the surface roughness. Moreover, an increase in the surface smoothness of the film will increase the dielectric constant of the composite films. The feasibility of this new evaluation method was confirmed after evaluating films with different smoothness and the results of the film surface smoothness scans were compared. This method allows for a fast, large-scale determination of samples and is independent of the film transparency.

Reprint of: Improving oxidation and wear resistance of TiB2 films by nano-multilayering with Cr

Alternating TiB2-DCMS and Cr-HiPIMS layers are used to fabricate TiB2/Cr multilayer films with varying the Cr interlayer thickness, 2 and 5 nm, and the substrate bias during growth of Cr interlayers from floating, to −60 V and −200 V. The effects of multilayer structure on mechanical properties, static oxidation, and tribological behavior of the TiB2/Cr multilayers are investigated. The results reveal that TiB2 nanocolumns renucleate at each Cr interface maintaining smooth film surface and film density. Interlaying with Cr with thicknesses of 2–5 nm improves the resistance to oxidation at 500–600 °C as compared to TiB2 monolayer. The increase of the thickness of the Cr interlayers from 2 to 5 nm decreases the hardness of the multilayer slightly but deteriorates the wear rate significantly. The friction coefficients at 500 °C are lower than those at RT due to boric acid liquid lubrication induced by surface oxidation. The TiB2/Cr multilayer films show higher wear resistance than TiB2 monolayer. The multilayer films with 2 nm-thick Cr deposited at −60 V have the lowest recorded wear rates. Irradiation with 200 eV Cr+ leads to interface mixing, resulting in the formation of B-deficient TiBx phase (x < 2) and higher wear rates compared to multilayers grown at −60 V.