Preparation Of Films Research Articles

Photoresponsive Dioxazaborocanes-Containing Oligomers.

The synthetic methodology for the preparation of photoresponsive dioxazaborocanes-containing oligomers is developed. It relies on the transformation of the (diisopropylamino)boryl group (-BH(NiPr2)) into a dioxazaborocane unit in the presence of β-aminodiols and involves a bis-borylated dithienylethene photochromic unit. The photophysical properties of the obtained oligomers are evaluated as well as their processability for the preparation of spin-coated films. The photomechanical behavior of the resulting films is assessed via displacement tracking profile.

Study on the Polymer Morphology and Electro-Optical Performance of Acrylate/Epoxy Resin-Based Polymer-Stabilized Liquid Crystals Based on Stepwise Photopolymerization.

Stepwise photopolymerization is a miraculous strategy modulating the polymer skeleton and electro-optical properties of light modulators based on liquid crystal/polymer composites. However, owing to the indistinct polymerization mechanism and curing condition discrepancy, the required polymer structures and electro-optical properties are hard to be controlled precisely. Herein, a novel polymer-stabilized liquid crystal film based on acrylate/epoxy resin is proposed, fabricated and the relationships between preparation process, polymer content, polymer morphology and electro-optical properties are studied. The in-situ photopolymerization of acrylate/epoxy resin liquid crystalline polymer is fulfilled using cation photo-initiator UV 6976. The distinct photopolymerization speed between acrylate and epoxy resin benefits the polymer morphology control, and with accurate containment of the polymerization process and polymer composition, the superior electro-optical properties at a higher polymer content are acquired. The polymer morphology and electro-optical properties are influenced by the polymer content and mass ratio between acrylate and epoxy resin. The best electro-optical properties among samples are attained by controlling the mass ratio between acrylate and epoxy resin to 1:1, integrating higher densities of scattering centers and lower anchoring effect. With higher polymer content, the strategy of increasing the mass ratio of E6M benefits the improvement of E-O properties for alleviating polymer density. This work provides insights to stepwise polymerization of liquid crystalline monomers and offers a fancy strategy for the preparation of novel liquid crystal dimming films.

CHARACTERIZATION OF COATINGS PREPARED FROM PREVULCANIZED NR/POLYANILINE LATEX

ABSTRACT Latex consisting of a NR/polyaniline (NR/PAni) blend is used in the preparation of thin elastic films. In this study, NR/PAni latex blends with different amounts of doped PAni and surfactants (sodium dodecylbenzene sulfonate [SDBS] and sodium dodecyl sulfate [SDS]) were prepared through prevulcanization. The films were prepared from prevulcanized latexes by casting in a petri dish or with the spin coating method. The conditions suitable for prevulcanization were investigated. The effect of doped PAni amounts and the surfactants SDBS and SDS on the mechanical, electrical conductivity, and physico-chemical surface properties and morphologies of NR/PAni films were characterized. The results indicated that PAni doped with dodecylbenzene sulfonic acid (DBSA) was well dispersed in NR latex in the presence of 0.01 mol/w% of SDBS. The highest amount of doped PAni that was dispersed was 17 w/w%. The properties of the blend of NR and DBSA-doped PAni were superior to those of the other blends. The compatibility between SDBS and DBSA was the dominant factor in improving the properties of the film prepared from the prevulcanized NR/PAni latex blend.

Formulation and evaluation of melatonin as fast dissolving oral strips using combined polymers

Background and objective: Fast-dissolving oral thin film (FDOF) is a novel and most advanced form of solid dosage form that dissolves or disintegrates in 1 minute when put in the mouth without water or chewing. Pre-gastric absorption of FODFs from the mouth, pharynx, and esophagus as saliva flows down into the stomach would improve the therapeutic benefit of the drug as oral films disintegrated in the mouth. The study is designed and purposed to use most water soluble, best type and concentration of polymers to be selected for use in combination to formulate melatonin oral thin films. Different types of synthetic water soluble polymers were utilized the preparation of films (hydroxypropyl methyl cellulose HPMC15M, sodium carboxy methyl cellulose NACMC). Methods: Solvent casting method was performed for preparation of twelve placebo films at the beginning, to obtain and select suitable polymer type and concentration for use in combination to be formulated for drug loading. The films were evaluated for their characteristics like mechanical properties (thickness and folding endurance), surface pH and disintegration time. Percentage of release and assay of melatonin was taken. Comparison studies were performed on melatonin films from this study with melatonin oral disintegrating tablets release profiles. Best batch could be selected. Drug-excipient compatibility carried out as pre formulation study to see whether there is interaction between the drug and excipients used. Results: Results from FT-IR showed no interaction between melatonin and polymers used, the prepared formulations were clear, transparent, non-sticky and easily removed from the plate surface with the thickness ranging from (0.04-0.07) mm depending on the polymer concentration. The times required for the films to disintegrate was ranging from 21-26 seconds, and the majority of melatonin was released within first 2 minutes within the dosage form. Conclusion: Melatonin can be formulated as fast dissolving oral films using combination of water-soluble polymers by solvent casting method to obtain ease of administration without using water during administration, fast onset of action resulted from rapid disintegration.

Preparation and Characterization of Chitosan-Gelatin Film for Wound Dressing

This study aims to explore the effect of various components of chitosan gelatin on its characteristics. The method used was drying at room temperature using petridish for 2-3 days, by mixing all raw materials with chitosan : gelatin weight ratio of 1:0, 0:1, 1:1, 1:2, and 2:1. The dried film was taken and tested for film characteristics. The analysis conducted was FTIR analysis, swelling analysis, and degradation analysis. The results of the swelling analysis showed that the more the addition of gelatin composition, the percentage of swelling increased as shown in the ratio of 1:2, namely 85.178%, 144.072%, 102.068%, 184.660%, 135.272%. Meanwhile, the degradation test results showed that the chitosan and gelatin films with various composition variations increased as the test time progressed. FTIR analysis revealed that gelatin (Ge), chitosan (Ch), and chitosan-gelatin mixture (Ch-Ge) with 1:1 ratio had similar absorption peaks.

Interfacial Assembly of Free-Standing Polymer-Phenolic Films for Antibacterial and Antiultraviolet Applications.

We report a facile interfacial assembly strategy for the preparation of flexible polyphenol-based films for antibacterial and antiultraviolet applications. The free-standing films can be instantaneously formed via spraying tannic acid (TA) at the surface of carboxymethyl chitosan (CMCS) solutions. Compared with the traditional casting-evaporation procedure on solid substrates, the liquid interfacial assembly method for the construction of free-standing films is rapid and facile, which prevents the interface separation procedure from the substrates. The thickness and mechanical properties of the films are well controlled by changing the incubation time. The low-field nuclear magnetic resonance was used to analyze the water distributions inside the films and to distinguish the cross-linked structure of CMCS-TA films with different thicknesses, revealing the dynamics of the film formation process. Importantly, the films exhibit outstanding antibacterial and antiultraviolet properties, which are promising in the applications of wound dressings. This study provides a new avenue for the assembly of flexible free-standing films with multifunctionality via a facile and low-cost fabrication process.

Understanding vapor phase growth of hexagonal boron nitride.

Hexagonal boron nitride (hBN), with its atomically flat structure, excellent chemical stability, and large band gap energy (∼6 eV), serves as an exemplary 2D insulator in electronics. Additionally, it offers exceptional attributes for the growth and encapsulation of semiconductor transition metal dichalcogenides (TMDCs). Current methodologies for producing hBN thin films primarily involve exfoliating multi-layer or bulk crystals and thin film growth via chemical vapor deposition (CVD), which entails the thermal decomposition and surface reaction of molecular precursors like ammonia boranes (NH3BH3) and borazine (B3N3H6). These molecular precursors contain pre-existing B-N bonds, thus promoting the nucleation of BN. However, the quality and phase purity of resulting BN films are greatly influenced by the film preparation and deposition process conditions that remain a substantial concern. This study aims to comprehensively investigate the impact of varied CVD systems, parameters, and precursor chemistry on the synthesis of high-quality, large scale hBN on both catalytic and non-catalytic substrates. The comparative analysis provided new insights into most effective approaches concerning both quality and scalability of vapor phase grown hBN films.

Preparation of 2D AlxGa1-xN film via printing liquid metals

AlGaN film is a promising barrier layer widely used in high electron mobility transistor. Facile preparation of 2D AlGaN with high quality is still a challenge for traditional process. In this work, high quality 2D AlxGa1-xN (mixture of AlN and GaN) is synthesized by using liquid alloy printing technique and post nitriding treatment. The prepared 2D AlxGa1-xN shows good crystallinity and ultra-wide bandgap of 5.55 eV. Besides, the 2D AlxGa1-xN is a n-type semiconductor and can act as channel layer in field effect transistor. This novel process provides a facile way to obtain 2D AlxGa1-xN film, which will have a potential application in AlGaN/GaN heterostructure field effect transistors.

Micropatterning of LaCoO3 thin films through a novel photosensitive sol-gel lithography technique and their magnetic properties

This paper presents a study on the microstructure and magnetic properties of LaCoO3 (LCO) thin films, and also the micropatterning of LCO thin films using a novel photo-sensitive sol-gel lithography method. It is found that higher heat-treatment temperature can promote the healing of cracks and filling of pores, resulting in refining the grains, and improving the density of LCO film. The film treated at 850 °C has a larger nucleation energy, which makes the distribution of nucleation sites more uniform, promoting the healing of cracks and filling of pores, refining the grains, and improving the density of LCO film. LCO precursor sol, metal chelates with UV photosensitivity were synthesized by adding BzAcH photosensitizer. LCO micro-arrays with diameters of 50 μm, as well as other fine patterns with a minimum line width of about 2 μm were successfully prepared by a UV mask lithography technique. In contrast, our novel lithography method eliminates the need for photoresist, as the fine pattern is formed during the preparation of the LCO gel film, which is the advantages of our lithography method over traditional techniques.

Scalable In-situ Microfibrillar dielectric films: Achieving exceptional energy density and efficiency

It is a formidable challenge to develop a feasible strategy for the scalable fabrication of all-organic dielectrics with simultaneous improvements in both discharged energy density (Ud) and efficiency (η). Herein, an innovative technology of “melting extrusion-hot stretching-quenching” was put forward for the large-scale preparation of all-organic polymer dielectric films, where polymethyl methacrylate (PMMA) was miscible with polyvinylidene fluoride (PVDF) to form single dispersed phase in the polypropylene (PP) matrix and in-situ transformed into microfibrils with the aid of elongational flow field. Thereby, a simultaneous enhancement in the dielectric constant and breakdown strength was achieved and the as-prepared PP-based all-polymer dielectric film exhibited an unprecedented ultrahigh Ud of 9.6 J cm−3 and an exceptional η of 90.9 %. Experimental verification and computational simulation confirmed that the formation of highly oriented PMMA/PVDF microfibrils and well-aligned interfaces are constructive to enhancing breakdown strength by suppressing electric field distortion. The highly oriented dipoles in PVDF and PMMA, coupled with the eliminated ferroelectric behavior of PVDF, synergistically contributed to the heightened Ud and η. The approach presented in this work opens up a promising avenue for the large-scale production of all-organic capacitor films with enhanced Ud and η, heralding a new era of advanced dielectric materials.

Enhanced dipole-interaction in Nd-Dy-Fe-Co-B/Fe composite thick stacked trilayer

It is crucial to better understand the magnetization reversal process between soft and hard magnets and to achieve a high maximum energy product in thick composite multilayers. In this study, we find that the exchange interactions dominate in soft–hard-magnetic composite bilayers, while dipole interactions are predominant in soft–hard-magnetic composite trilayers. Based on the first-order reversal curve, magnetization reversal models are developed for both the thick composite bilayer and trilayer. Dipole interactions play an important role in the long range, resulting in higher coercivity and remanence in the thick trilayer. A multilayer in a stacked trilayer structure is achieved, which is composed of thick films with a perpendicular magnetic anisotropy at a thickness of up to 16 μm. The enhanced dipole interactions lead to a remanent polarization of 1 T and a maximum energy product of 22.5 MGOe. This work contributes to the preparation of thick films with a high maximum energy product for applications in magnetic microelectromechanical systems.

Confinement Effect in Multilayer Films Made from Semicrystalline and Bio-Based Polyamide and Polylactic Acid.

Bio-based multilayer films were prepared by using the innovative nanolayer coextrusion process to produce films with a number of alternating layers varying from 3 to 2049. For the first time, a semicrystalline polymer was confined by another semicrystalline polymer by nanolayering in order to develop high barrier polyamide (PA11)/polylactic acid (PLA) films without compromising thermal stability and mechanical behavior. This process allows the preparation of nanostratified films with thin layers (down to nanometric thicknesses) in which a confinement effect can be induced. The stratified structure has been investigated, and the layer thicknesses have been measured. Barrier properties were successfully correlated to the microstructure, as well as the thermal behavior, and mechanical properties. The layer continuity was fully achieved for most of the films, but some layer breakups have been observed on the film with the thinnest PLA layer (2049-layers film). Coextruding PLA with PA11 has induced an increase in PLA crystallinity (from 4 to 16%) along with an increase in thermal stability of the multilayer films without impacting PA11 properties. Gas barrier properties were driven by the PLA confined layers due to the microstructural rearrangement by increasing crystallinity, whereas water barrier properties were governed by the PA11 confining layers due to its lower water affinity. As a consequence, a decrease of water permeability (up to 11 times less permeable for the 6M film) but an increase of gas barrier properties (barrier improvement factor (BIF) of 66% for the 0M film for N2 and BIF of 36% for the 6M film for CO2 for instance) were evidenced as the layer number was increased. This study paves the way for the development of ecofriendly materials with outstanding barrier performances and highlights the importance of nonmiscible polymers adhesion at melt state and additives presence.

Influence of Deposition Parameters on the Plasmonic Properties of Gold Nanoantennas Fabricated by Focused Ion Beam Lithography.

The behavior of plasmonic antennas is influenced by a variety of factors, including their size, shape, and material. Even minor changes in the deposition parameters during the thin film preparation process may have a significant impact on the dielectric function of the film, and thus on the plasmonic properties of the resulting antenna. In this work, we deposited gold thin films with thicknesses of 20, 30, and 40 nm at various deposition rates using an ion-beam-assisted deposition. We evaluate their morphology and crystallography by atomic force microscopy, X-ray diffraction, and transmission electron microscopy. Next, we examined the ease of fabricating plasmonic antennas using focused-ion-beam lithography. Finally, we evaluate their plasmonic properties by electron energy loss spectroscopy measurements of individual antennas. Our results show that the optimal gold thin film for plasmonic antenna fabrication of a thickness of 20 and 30 nm should be deposited at the deposition rate of around 0.1 nm/s. The thicker 40 nm film should be deposited at a higher deposition rate like 0.3 nm/s.

Preparation of zein active films with antimicrobial and antioxidant properties by incorporating gallic acid loaded γ-CD-MOF for pork preservation

The growing concerns over food contamination caused by microorganisms, coupled with the worsening environmental impact of petroleum-based plastics have drawn significant attention to eco-friendly materials in food packaging. Herein, cyclodextrin-metal-organic framework (CD-MOF) was prepared as promising nanocarrier for the natural product gallic acid (GA). Then, the prepared material (GA@CD-MOF) was incorporated into zein matrix to obtain Zein-GA@CD-MOF films. Further studies showed that the composite films possessed great potential for food packaging, offering excellent UV-light blocking, water resistance, and mechanical properties. Notably, Zein-GA@CD-MOF films demonstrated superior antimicrobial activity (44.56%–77.97% against Escherichiacoli O157:H7 and 28.36%–59.49% against Salmonellaenterica) and sustained antioxidant properties for 100 days, which correlated with the sustainable release effect of GA. Furthermore, the exceptional biosafety of GA@CD-MOF has been confirmed through cytotoxicity and hemolysis assays. Pork preservation experiments illustrated that the obtained films could retard protein degradation, microorganism growth, and lipid oxidation, extending the shelf-life by 9 days at 4 °C. These findings suggest that Zein-GA@CD-MOF films has promising application prospects in pork preservation packaging.

The influence of molecular weight on the anticorrosion properties of chitosan coatings

The effort to replace toxic compounds with natural alternatives led to intensive investigations on the use of polysaccharides as coatings for corrosion protection. Biological macromolecules, such as chitosan, demonstrate great potential for the development of sustainable anticorrosion coatings. However, the role played by important properties, such as molecular weight, on the performance of the coatings, remains unclear. In this paper, the influence of molecular weight on the anticorrosion properties of chitosan coatings is investigated using AA2024-T3 aluminum alloy as substrate. Chitosan of three different molecular weights were used for the preparation of coatings and free-standing films, and their properties (morphology, swelling degree, and water contact angle) were evaluated. The corrosion performance of the coated samples was investigated by an atmospheric corrosion essay and by electrochemical impedance spectroscopy, in NaCl 3.5 % solution. The results show that the low-molecular-weight chitosan coatings present the lowest swelling degree (603 %), highest water contact angle (86.4°), lowest porosity, and superior performance in both corrosion tests, reaching impedances close to 105Ωcm2 even after seven days of exposure to corrosive solution.

Improved preparation of AgNW film and its application in flexible counter electrodes of dye-sensitized and perovskite solar cells

Silver nanowire (AgNW) has been wildly used to prepare flexible conducting substrate of electronic and optoelectronic devices. By coating a layer of carbon onto a polymer/AgNW substrate, a counter electrode (CE) was obtained and it offers the advantages of high flexibility, light weight, low cost, simple fabrication, and operating efficiently in dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs). By modifying the traditional unidirectional roll-coating process of AgNW to cross-directional coating, the morphology and distribution of the AgNW network was improved, which led to increased transmittance and electroconductivity, and subsequently improved cell efficiency of DSSCs and PSCs. The performance of the CEs and solar cells was further promoted by optimized fabrication process of the carbon layer. The as-prepared flexible CEs achieved great enhancement of cell efficiencies, and maximum power conversion efficiencies of 5.17% and 14.32% were obtained by DSSCs and PSCs, respectively.

The preparation of low-cost tungsten oxide films by solution-coating technique and NIR annealing for high-performance complementary electrochromic devices

Electrochromic devices can adjust their transparency by applying an electrical voltage and serve as intelligent window systems for managing incoming sunlight. In this study, we employed an environmentally friendly, large-area solution coating method to form tungsten oxide (WO3) thin films for the fabrication of electrochromic devices. We applied a WO3 precursor solution, with water as the primary solvent, onto ITO glass through blade coating and utilized near-infrared (NIR) light annealing for drying in order to rapidly optimize the film characteristics. The resulting WO3 film, combined with an ion storage layer – either sputtered NiO or blade-coated Prussian Blue (PB) - and injected with a UV-curable electrolyte, resulted in a complementary electrochromic device that exhibited good performance characteristics. For the device with NiO as the ion storage layer, the optical transmittance modulation (ΔT) can achieve 50 % at a wavelength of 680 nm, maintaining a ΔT of 45 % after 3000 coloration-bleaching cycles. For the device with PB as the ion storage layer, the ΔT achieved 64 % at 630 nm, maintaining a ΔT of 60 % after 3000 coloration-bleaching cycles. Therefore, we believe this WO3 solution coating technique combined with rapid NIR annealing technology holds promise as a low-cost and efficient method for the future production of electrochromic devices.

Formulation and evaluation of bioadhesive buccal Films of Domperidone co-crystals by using Tamarind kernel powder as mucoadhesive polymer

As solubility plays key role in drug dissolution and bioavailability lots of techniques to enhance solubility are evolved. One of the techniques is co crystallization. The main aim of the work is to enhance the solubility of domperidone by co crystallization using coformers like Para amino benzoic acid and succinic acid. The cocrystals were evaluated for melting point and solubility enhancement. these cocrystals were used to prepare buccal films by solvent casting method. In the preparation of buccal films Tamarind kernel powder obtained from the seeds of Tamarind is used as mucoadhesive polymer and Hydroxy propyl methyl cellulose as film former, Polyethylene glycol 6000 as plasticizer, dehydrated banana powder as super disintegrant, sodium saccharin as sweetener and mixture of ethanol and water as solvents. The mucoadhesive strength of Tamarind kernel powder was determined using modified physical balance method. Four buccal films were prepared in which PDBF1 and PDBF2 are the two buccal films prepared using cocrystals of domperidone and Para amino benzoic acid and other two buccal films SDBF1 and SDBF2 with cocrystals of domperidone and Succinic acid. The buccal films were evaluated for different tests like folding endurance, swelling index and Surface pH. In vitro diffusion studies were conducted by Franz diffusion cell using egg membrane as semipermeable membrane and phosphate buffer of pH 7.4. The buccal films prepared with cocrystals of domperidone and succinic acid at weight ratio 1:2 has shown 86%drug release. The work has concluded that there is fold increase in aqueous solubility of Domperidone and the optimized formula is SDBF2 and Tamarind kernel powder can be used as mucoadhesive polymer in novel drug delivery systems. Keywords: co crystals, solvent evaporation, muco adhesive, buccal films, solvent evaporation

Regulation of Brightness Attributes of High-Stability Carbon Quantum Dots Applicable in LED Digital Color Display.

Fluorescent carbon dots (CDs) attract much attention due to high stability and low toxicity. For high brightness, multi-color emission and fluorescence stability, polystyrene (PS)/CDs composite films were prepared. First, three types of CDs and three PS/CDs films were prepared. Then, three light-emitting-diode (LED) devices were achieved. Compared to CDs solutions, CDs filled films show almost unchanged photoluminescence (PL) spectra. PL peaks of blue, green and red films appear at 462nm, 544nm and 603nm, separately. Blue CDs lead to highest photoluminescence quantum yields (PLQYs) of 76% (solution) and 49% (film). A certain level of thermal stability and fluorescent reversibility of blue film were verified. After 60 days of air exposure, PL intensities of blue and green films reach 97% and 93% of original values, separately. Improving work time cannot vary PL wavelengths of devices. For blue-emitted device, PL intensity reaches 55% of original value after working for 600min. For green-emitted device, PL intensity reaches 80% after working for 300min. The novelty is effective PS encapsulation and uniform dispersion of CDs to yield favorable fluorescence properties of devices. This work inspires ideas for large-scale preparation of fluorescent films for LED digital color display.

Molecular dynamics simulation of hybrid structure and mechanical properties of DLC/Ni-DLC thin films

To improve the mechanical properties of the rolling body surface of wind power bearings, extend its service life. In this study, a large-scale molecular/atomic parallel processor LAMMPS was introduced, and then the process of magnetron sputtering technology in the preparation of DLC/Ni-DLC thin films on the 42CrMo substrate material was simulated. The effects of deposition parameters such as sputtering temperature, sputtering voltage, deposition air pressure, and Ni doping on the residual stress, film base bonding, and organizational structure of the thin films were investigated. The simulation results show that for different deposition parameters, the atomic tensile and compressive stresses existed simultaneously in DLC/Ni-DLC films, and the residual stresses were between − 0.504–5.003 Gpa and − 2.11–0.065 Gpa, respectively; the doping of Ni effectively improved the distribution of hybrid structure and the mechanical properties of the DLC films, and the ratio of the sp3 hybrid structure in the film organization was about 2.56 times higher than that of the non-doped films, and the membrane base bonding force was increased by 32.78% and the residual stress is reduced and transitioned from tensile stress to compressive stress. In addition, it was observed that the thickness of the mixed layer of DLC/Ni-DLC films with the substrate was not increased after the thickness of the mixed layer was extended to about 2 nm. Nickel doping and reasonable control of deposition parameters help to reduce the residual stress and improve the bonding strength of the film by changing the organizational structure of the film, which provides an important theoretical and scientific basis for the preparation of low-stress, high-performance and long-life DLC films and the wide application of rolling bodies for wind power bearings under complex working conditions.