Film Coatings Research Articles

Enhanced mechanical and biocompatibility performance of Ti(1-)Ag(x) coatings through intermetallic phase modification

Advanced materials combining superior mechanical and biocompatibility performance are of significant interest to extend the lifetime of biomedical devices. In this work, Ag is alloyed with Ti to investigate the role of emerging Ti Ag intermetallic coatings with high mechanical hardness and exceptional biocompatibility. Thin films of Ti (1- x ) Ag (x) were deposited on 316 L steel and glass substrates using magnetron sputtering and subsequently heat-treated to aid Ti Ag intermetallic development. Mechanical properties were then measured and correlated to microstructural and morphological changes in the Ti Ag films. In the as-grown state, the Ti Ag matrix developed different intermetallic structures which increased the hardness of pure Ti films from 5 to >7 GPa. After heat treatment, a peak hardness of 7.39 GPa and elastic modulus of 105 GPa was achieved for a 43 at.% Ag film due to formation of the tetragonal Ti Ag phase and increase of upper surface oxides which act as dislocation barriers. However, at higher Ag concentrations, heat treatment leads to agglomeration of Ag around grain boundaries and decreases the crystallite size, leading to reduction in hardness to <3 GPa. The Ti rich films also depict better cytotoxicity performance following exposure to the L929 cell line, though excellent cell viability values >98% are observed for the entire Ti Ag range. While leached ion concentrations lower than 100 ppb demonstrate excellent biocompatibility of this Ti Ag alloy system. This work demonstrates the first successful attempt to develop biocompatible Ti Ag thin film coatings with high mechanical hardness with the potential to extend the lifetime of medical implants. • First study on biomechanical performance of Ti (1-x) -Ag (x) intermetallic films. • First report on external heat treatment to develop Ti Ag intermetallic thin films. • Ag addition causes transition to tetragonal Ti Ag structure with enhanced hardness. • Heat treatment leads to improved crystallinity and mechanical performance. • Ti Ag films exhibit excellent biocompatibility before and after heat treatment.

Antimicrobial and Gas Barrier Crustaceans and Fungal Chitin-Based Coatings on Biodegradable Bioplastic Films

Chitin nanofibrils (CN) can be obtained from crustaceans and fungal sources and can be used for preparing coatings for bioplastic films, that are fundamental for developing a safe and sustainable biodegradable food packaging. Coatings with different concentrations of CN from shrimps were applied on different bioplastic substrates, like Poly (butylene succinate-co-adipate)/Poly(3-hydroxybutyrate-co-3-hydroxyvalerate (PBSA/PHBV) blend, Polybutylene succinate (PBS), and Polybutylene adipate terephthalate/Poly(lactic acid) (PBAT/PLA) blend, but the adhesion to the substrates was scarce. On the contrary, the fungal-based CN showed a better adhesion. Additionally, it was found that the use of an additive based on oligomeric lactic acid was useful to prepare a coating with an improved adhesion to bioplastics. The gas barrier properties to oxygen and water vapour of coated and un-coated films were measured, revealing an improvement of these properties thanks to applied coatings, especially towards the oxygen. Antimicrobial properties and biodegradation capacity were also evaluated revealing an antibacterial effect of the coatings that did not significantly interfere with their biodegradability. The results are discussed and interpreted considering the correlation between composition and macromolecular structures with the observed functional properties.

Problems of Applying Film Coatings During Scale-up Technology

Introduction. Technology transfer is an integral part of the life cycle of any drug. The coating is a critical step in the production of coated tablets. The transfer of the film coating application process is often accompanied by the rejection of a part of the drug series due to various defects in the target surface.Aim. To classify the types of defects formed at the stage of “Application of the film shell” in the devices of the “Coater” drum type, to identify the causes of occurrence, to develop ways to eliminate these defects.Materials and methods. Film-coated tablets with INN diosmin, sildenafil, dipyridamole, atorvastatin, rosuvastatin as the object of the study were selected. The samples were obtained on a single-punch tablet press EP-1 (ERWEKA GmbH, Germany) and coated with a film shell in a coating unit of the type "copper" BGB-1 (Chongqing Jinggong Pharmaceutical Machinery Co., Ltd., China).Results and discussion. Appearance defects are classified according to the degree of criticality: critical (influx, chipping, recess, rupture, delamination, breaking, rubbing, sticking, pigmentation, discoloration, scratches, crack), significant (build-up, inclusion), minor defect. The main causes of the defect have been established: the property of the core tablet (for example, poor adhesive properties, hydrophobicity), technological parameters of the process (the speed of rotation of the drum, the speed of spraying, the pressure on the spray, the pressure on the formation of the torch, the temperature of the incoming air. The main consequences of the occurrence of each type of defect are considered, among which are insignificant (not affecting the quality) and critical (affecting the quality indicators of "dissolution").Conclusion. In the course of the study, the types of critical and significant defects, the causes of occurrence and ways to eliminate these defects are considered.

THE ANTI-INFLAMMATORY TABLET FORMULATION OF COLEUS (PLECTRANTHUS SCUTELLARIODES) LEAVES EXTRACT USING KOLLICOAT®PROTECT COATING

Objective: The purpose of this study was to find the concentration of weight gain on the use of Kollicoat®Protect to produce coleus leaf extract film-coated tablets with good physical properties.&#x0D; Methods: Coleus extract was obtained by maceration using 70% ethanol. Tablet cores were prepared using the wet granulation method, then evaluated (uniformity of weight, size, hardness, friability, and disintegration time). Coated tablets were made in four variations of polymer weight gain, i.e. 5, 6, 7, and 8%. To determine the effect of the weight gain concentration of Kollicoat®Protect an evaluation of the coated tablets was carried out, i.e. the uniformity of weight, size, hardness, disintegration time, and physical appearance of the film-coated tablets.&#x0D; Results: The four variations (Film Coated Tablet, FCT 5, 6, 7, and 8%) in weight gain of film-coated tablets showed the physical appearance results per the applicable requirements. However, the physical observation test at room temperature showed the instability of the film-coated tablet. The qualitative analysis of thin-layer chromatography showed that the productive substances in the extracts, tablet cores, and film-coated tablets were still contained even though they had undergone several formulation stages.&#x0D; Conclusion: Film-coated tablets met the standards of the Indonesian Pharmacopoeia and the United States Pharmacopeia. After two weeks, there was slight instability in film-coated tablets at room temperature storage. The extract, tablet core, and film-coated tablet contain flavonoids.

Self-growing nano-liquid-crystal film from dynamic swollen hydrogel substrates.

A hydrogel which spontaneously swells in an aqueous polymer solution was observed to produce a new hydrogel film coated on its swollen surface. Here, inspired by this phenomenon, we theoretically formulate the dynamics of isotropic-to-nematic (I-N) phase transition caused by swelling a hydrogel substrate (HS) in a dilute nanoplatelet suspension, and quantitatively characterize a self-growing nano-liquid-crystal (NLC) film coated on the swollen HS surface. We show that as the HS gets softer, the resulting NLC film can form earlier and achieve greater thickness (up to hundreds of micrometers). Our results and the existing experiments confirm that the growth dynamics of the NLC film or hydrogel film is exclusively regulated by the swelling behaviors of the HS instead of suspension configurations, e.g., I-N phase transition or sol-gel transition, suggesting a universal signature for the solutes ranging from molecules to colloids. However, both the maximum thickness of the NLC film and the corresponding characteristic time rely highly on the inherent elasticity of the HS and nanoplatelet aspect ratio. We demonstrate that the swelling quasiequilibrium state rather than the equilibrium state of the HS is more qualified to formulate a condition which is practically significant in preestimating the moment when the maximum thickness of the NLC film appears. Our theoretical framework serves as a robust paradigm to extensively rationalize (bio)film coatings which self-integrate with diverse nanostructural configurations via swelling-induced phase transition.

Influence of mechanical properties of coating and substrate on wear performance of HDLC and TiN-coated AISI 5140 alloy steel

This paper investigates the mechanical and wears resistance properties of AISI 5140 alloy steel coated with thin films of hydrogenated diamond-like carbon (HDLC) and titanium nitride (TiN). HDLC and TiN films were sputtered onto AISI 5140 alloy steel samples using the magnetron sputtering technique. In addition to coatings, the metallic substrates were also evaluated for hardness and wear resistance. The findings on wear losses, patterns, and wear trace widths were determined after the wear tests. In tribological tests, a variety of wear patterns were observed on both thin film coatings. The primary wear mechanisms of TiN coatings were found to be tribochemical wear, substrate material loss, and wear debris. However, the HDLC coating experienced wear due to ploughing action, with minor patches of the thin film being removed from the underlying material, but scanning electron microscopy observations showed no detectable wear. Using Raman spectroscopy, the structural properties of HDLC were analyzed, and the findings were compared to those of wear patterns. The results showed that the coating significantly improved the wear resistance of the AISI 5140 alloy steel and that the TiN-coated AISI 5140 alloy steel sample was more comparable to wear than the HDLC-coated AISI 5140 alloy steel sample. It is also shown that, as compared to an uncoated metallic substrate, the resilience of thin film coated components is a key factor impacting component life.

Effect of Deposition Temperature on the Surface, Structural, and Mechanical Properties of HfO2 Using Chemical Vapor Deposition (CVD)

A high-temperature-resistant and high-performance hafnium oxide (HfO2) coating for aerospace engines was developed. HfO2 thin film coatings were prepared by chemical vapor deposition (CVD) at 1200, 1250, 1300, and 1350 °C, respectively. The crystal structure and surface morphology of the HfO2 thin films at different deposition temperatures were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The effect of deposition temperature on the mechanical properties of the HfO2 thin films was studied by means of the drainage method and nanoindentation. The results showed that the HfO2 coatings deposited at different deposition temperatures are monoclinic crystal structures, and the surface morphology changes from cellular particles to columnar particles, and finally, to a loose and porous layered structure. When the deposition temperature is 1300 °C, the density of the HfO2 film is the highest, 9.62 ± 0.03 g/cm3, and the hardness is the highest, 7.33 ± 0.04 GPa. A HfO2 coating with the best comprehensive mechanical properties was prepared by changing the deposition temperature, which provided an experimental basis for the application of a HfO2 coating in the aerospace field.

Outside Front Cover: Plasma Process. Polym. 11/2022

Outside Front Cover: Plasma polymers have long been of interest as thin film coatings on biomedical devices and products, to generate desirable surface properties for favourable bio-interfacial interactions. The cover image symbolically depicts plasma's versatility in its ability to modify biomedical surfaces for various purposes. From its role in fundamental research on cell-interfacing surfaces and its use in modifying laboratory materials, plasma's utility is also apparent in the development of commercial healthcare products. This article is part of the virtual issue on Plasmas for Biointerfaces, volume 19, issue 10. Further details can be found in the article by Bryan R. Coad, Pietro Favia, Krasimir Vasilev, and Hans J. Griesser (e2200121) (© Image provided by Bryan Coad)

Coatings from high-entropy alloys: State and prospects

The authors made a brief review of recent publications by foreign and domestic researchers on the structure, phase composition, and properties of films and coatings of five-component high-entropy alloys (HEA) on various substrates and modification of the HEA surface by various types of processing. The main methods of applying films and coatings are considered: magnetron sputtering, thermal sputtering, laser sputtering, and electrodeposition. Particular attention is paid to the deposition of coatings on stainless steels and titanium alloys. The positive change in the tribological, strength properties, and corrosion resistance of film coatings in a wide temperature range is analyzed and possible causes of the observed effects are discussed. The role of solid solution strengthening, formation of fine-grained structure, and the formation of oxide layers enriched with one of the HEA components were taken into account. The authors identified new methods for applying coatings from HEA and subsequent processing. Using Nb and Ti doping as an example, their role in increasing microhardness, wear resistance, and reducing the friction coefficient in coatings were revealed. Electrolytic polishing, electroerosive machining, mechanical polishing and their combination are considered among the methods of HEA surface treatment. A number of works propose a method of powder borating to increase the surface strength and wear resistance of HEAs. The paper considers analysis of works on electron-beam processing as one of the promising and high efficient methods of HEA surface hardening.

Modification of polymethylmethacrylate under irradiation of the SEM electron beam

This paper is focused on the study of the modifications of polymethymethacrylate (PMMA) under irradiation of electron beams. PMMA is a well-known thermoplastic synthetic polymer, with unique features such as transparency, good tensile strength, and moldability. Its performance can be significantly modified through the realization of functionalized thin film coatings, ion irradiations, laser irradiations for different applications, such as flexible electronics, biomaterials, dielectric layers and sensors. The purpose of this paper is to describe the changes of the PMMA features as a function of the energy and fluence of electron beams. The morphology of the obtained structures is studied by electron scanning microscopy while the C/O atomic ratios are monitored by the energy dispersive X-ray spectroscopy.

Comparison of the Robustness of Pellet Film Coating with and without In-Process Coating Thickness Evaluation

The robustness of the pellet coating process with and without the use of an in-process coating thickness analyzer (PATVIS APA) was investigated. Pellets containing model drug were coated with a prolonged release film coating, using different process conditions. In the first set of experiments film coating was performed as process repetitions with unintentional variation of process parameters, and in the second set, controlled changes (inlet air humidity, gap between distribution plate and Wurster partition, starting pellet load) were made. Within the first set of experiments, the coating process endpoint was determined either via gravimetric consumption of coating dispersion or by means of in-line coating thickness monitoring. The release profiles of the pellets were analyzed and the density of coating calculated. Both methods of the process endpoint determination can be relatively robust in batch processing, if key factors influencing drug release profile are under control. PATVIS APA was shown to be a useful tool to better understand the coating process and can be helpful if coating process interruptions are encountered. Water content was shown to be the key factor influencing the drug profile, presumably by influencing the structure and thickness of the coating applied.

Modification of polymethylmethacrylate under irradiation of the SEM electron beam

This paper is focused on the study of the modifications of polymethymethacrylate (PMMA) under the irradiation of electron beams. PMMA is a well-known thermoplastic synthetic polymer, with unique features such as transparency, good tensile strength, and moldability. Its performance can be significantly modified through the realization of functionalized thin film coatings, ion irradiations, laser irradiations for different applications, such as flexible electronics, biomaterials, dielectric layers and sensors. The purpose of this paper is to describe the changes of the PMMA features as a function of the energy and fluence of electron beams. The morphology of the obtained structures is studied by electron scanning microscopy while the C/ O atomic ratios are monitored by the energy dispersive X-ray spectroscopy.

Tunable broadband absorption in continuous and porous textured Si/C bilayers: A comparative study

Effective light scattering, transmission and absorption play a pivotal role in optical devices. Significant progress has been recorded in this area via the application of surface texturing techniques and photo-friendly thin film coatings. Combining two facile and environmentally safe synthesis processes, a textured silicon (Si)/amorphous carbon (a-C) nanocomposite coating was formed on single crystal silicon substrates. A high purity silicon coating with the average thickness of 17 μm was formed via in situ magnesiothermic reduction reaction (MRR) of diatomaceous earth (DE) and spherical nanosilica at 750 °C and followed by a facile phase separation between polyacrylonitrile (PAN)/tetraethyl orthosilicate (TEOS) to create a porous a-C film. The porous/continuous PAN thin films were subsequently carbonized at 850 °C resulting in a textured Si/a-C film nanocomposite. Unlike polished or textured silicon surfaces, the a-C coated textured silicon surface showed high broadband absorption in excess of 60% in the range 300–1700 nm that compares well with most textured surfaces reported recently in the literature, and benefits from a facile and eco-friendly fabrication approach.

Fast and One-Pot Reductive Deposition of Continuous Uio-66 Films

UiO-66 (UiO stands for the University of Olso) film membrane is promising for molecular/ion separations owing to its sub-nano-sized pore apertures and superior chemical stability among the metal-organic framework (MOF) family, but the preparation of it remains difficult and challenging up to now. Here we report a fast and one-pot reductive deposition approach to the high-quality UiO-66 film coatings. In the deposition, the nitrate anions are introduced as pro-bases to accelerate the deprotonation of the ditopic linker-H2BDC (1,4-benzenedicarboxylic acid), which renders the continuous UiO-66 films coating in an hour. Importantly, the morphology of the deposited UiO-66 films can be well-tuned by the molar ratio of the ditopic linker to monotopic modulator because of their completing deprotonation process. The continuous, intergrown, and crystalline UiO-66 films can be obtained at optimized conditions (i.e., deposition temperature at 120 ℃, and the molar ratio of the linker to the modulator of 1:120). Besides, the proposed reductive deposition is also feasible for the fabrication of the analogues of UiO-66 with distinct ligands, like the Zr-fumaric films and Zr-naph (naph is the 1,4-naphthalenedicarboxylic acid) films. These deposited films can be prospective separation mediums for molecular sieving. Figure 1

Effect of immersion time and pH variation on the inhibition of AA2198-T851 alloy by leaching of anticorrosion pigments from free-standing films of organic coatings

In this work, organic coating films loaded with leachable anticorrosive pigments, cerium 4-hydroxycinnamate (Ce(4OHCin)3) and strontium zinc phosphosilicate (SZP 391) were immersed in 3.5% NaCl solution at pH 3, pH 5.6, and pH 10. Extracts from each bulk solutions were taken after 24 h, 72 h, 168 h, 240 h, and 336 h to quantitatively measure the leaching of the inhibitive species as a function of time using inductively coupled plasma optical emission spectroscopy (ICP-OES). Other part of the extracts was also employed as test solution to monitor the inhibitive properties of the leached species on AA2198-T851 substrates using electrochemical impedance spectroscopy (EIS). After the immersion process, the unexposed and exposed film surfaces were characterized using optical microscopy, transmission, and scanning electron microscopy (TEM & SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). The leaching test results confirmed the release of inhibitive species from the coating films into the test solutions, whose rate increased with immersion time but decrease with increasing pH of the bulk solution. Greater leaching rate was observed at the lowest pH, whose release follows non-Fickian diffusion. Furthermore, the EIS results indicated significant protection of the alloy and the efficiency increased with increasing immersion time and decreasing pH. The extract with Ce(4OHCin)3 pigment shows comparatively higher release rate and better inhibitive properties, with the best at the lowest pH 3. This is attributed to its smaller cluster size and high solubility. The optical and electron Microscopy, XRD and FT-IR of coating films have further complemented the leaching process by revealing pores left behind due to dissolution of large clusters. The pores networks provided excellent transport path for both inward migration of aggressive solution and the release of dissolved inhibitive species.

Enhanced photocatalytic activity of highly transparent superhydrophilic doped TiO2 thin films for improving the self-cleaning property of solar panel covers

Undoped and metal doped nanocrystalline TiO2 transparent thin films were synthesized on glass substrates via sol-gel/dip-coating method. TiO2 thin film coatings can be applied to the surfaces of solar panels to impart self-cleaning properties to them. The structural and optical properties of few nanometer-thick films were characterized by XRD, SEM, CA, AFM, XPS, and UV–Vis spectrophotometry techniques. The stoichiometric TiO2 films crystallized in anatase phase, with a particle size of ∼100 nm, which were uniformly distributed on the surface. The prepared films with a roughness of ∼1–5 nm, increased the hydrophilicity of the glass surface. Reducing the amount of Ti precursor (X) favored the improvement of film quality. To improve the photocatalytic activity of the TiO2 thin film, it was doped with Ni, Cd, Mo, Bi and Sr metal ions. The effect of metal doping on the photocatalytic activity of the films was investigated using the degradation process of methylene blue (MB) dye as the model contaminant. Among the prepared coatings, the Sr–TiO2 film showed the highest efficiency for MB degradation. It increased the dye degradation efficiency of the films under both UV and Vis lights. The kinetic investigations also showed that the degradation of MB by TiO2 and M − TiO2 films obeyed the pseudo-first order kinetics.

Plasma polymerization for biomedical applications: A review

AbstractPlasma polymers have long been of interest as thin film coatings on biomedical devices and products, to generate desirable surface properties for favorable bio‐interfacial interactions. Plasma polymers have also been used as platforms for the covalent immobilization of bioactive molecules. More recently, additional aspects have been investigated, such as selective prevention of adhesion of microbial pathogens, either via plasma polymers per se or including antimicrobial drugs. Plasma polymers have also been investigated for the release of silver ions and small organic molecules. Complementing low‐pressure plasma approaches, processes at atmospheric pressure have attracted interest recently, including for nano/biocomposite coatings. This contribution reviews the use of plasma polymers for intended biomedical applications, with a focus on more recent topic areas.

Controlled Synthesis of Chromium-Oxide-Based Protective Layers on Pt: Influence of Layer Thickness on Selectivity

Chromium-oxyhydroxide (CrxOyHz)-based thin films have previously been shown in photocatalysis and industrial chlorate production to prevent unwanted reduction reactions to occur, thereby enhancing the selectivity for hydrogen evolution and thus the overall process efficiency. Here, a highly reproducible synthesis protocol was developed to allow for the electrodeposition of CrxOyHz-based thin films with controlled thickness in the range of the sub-monolayer up to (&gt;4) multilayer coverage. Electrodeposited CrxOyHz coatings were electrochemically characterized using voltammetry and stripping experiments, allowing thickness-dependent film selectivity to be deduced in detail. The results are discussed in terms of mass transport properties and structure of the electrodeposited chromium oxyhydroxide films. It is shown that the permeation of diatomic probe molecules, such as O2 and CO, was significantly reduced by films as thin as four monolayers. Importantly, it is shown that the prepared thin film coatings enabled prolonged hydrogen oxidation in the presence of CO (up to 5 vol.%), demonstrating the benefits of thin-film-protected electrocatalysts. In general, this study provides insight into the synthesis and use of thin-film-protected electrodes leading to improvements in (electro)catalyst selectivity and durability.

Detrimental Effect of the Film Coat Chemistry and Thickness on the Physical Stability of Amorphous Solid Dispersions in Tablet Formulations

Amorphous solid dispersions (ASDs) have been widely utilized to enhance the bioavailability of pharmaceutical drugs with poor aqueous solubility. The role of various excipients on the amorphous drug to crystalline form conversion in ASDs has been widely documented. However, there has been no published study to investigate the role of film coating material on the physical stability of an ASD based tablet formulation, to the best of our knowledge. Here we show that the film coating can potentially have a detrimental impact on the physical stability of spray dried intermediates (SDI) in tablet formulations. The impact of the film coating on the physical stability of SDI was found to be related to the film coat material composition, and an increase in the film coating thickness led to a reduction in the physical stability of SDI in tablets. Oral compressed tablets in which the film coat material was “mixed-in” with the formulation blend showed a similar or worse physical stability than film coated tablets, further underscoring the film coat material impact on physical stability, independent of the film coating process. This study demonstrates a need for careful consideration of the film coat material selection for ASD based pharmaceutical product development.

Surface Structuring and Thin Film Coating through Additive Concept Using Laser Induced Plasma of Mg Alloy: A Comparison between the Presence and Absence of Transverse Magnetic Field (TMF)

In the present study, the influence of a 1.1 tesla Transverse Magnetic Field (TMF) on Laser-Induced Breakdown Spectroscopy (LIBS) of Mg-alloy plasma has been explored. The Mg plasma was produced using an Nd: YAG laser (1064 nm, 10 ns) at an intensity of 2 GW/cm2. Inert gases of Ar, Ne, and He were filled as environmental gases at pressures ranging from 1 to 100 Torr. Optical emission spectra from laser-produced plasma were detected with the help of a spectrometer, and plasma parameters such as excitation temperature (Texc) and electron number density (ne) were evaluated. Enhancement in the Mg plasma’s Texc and ne in the presence of TMF was noticed under all experimental conditions, including different ambient gases with varying pressures and time delays (0.42 µs–9.58 µs). Plasma confinement by applied TMF was analytically evaluated through thermal beta (βt) values, which were &lt;1 under all circumstances. The highest Texc and ne values (17,259 K and 11.5 × 1017 cm−3) for Mg-alloy plasma were obtained with ambient Ar in TMF, while the lowest values (8793 K and 1.0 × 1017 cm−3) were obtained in presence of He gas in the absence of TMF. SEM analysis was used to determine the surface structure of laser-ablated Mg alloy in the presence and absence of TMF. It revealed that the formation of cones, cavities, and non-uniform melting are characteristic features of ambient Ar, while spikes and cavities are prominent features in Ne gas environments. Conical spikes and dendrites are distinct features when ambient He is present. In comparison with the field-free condition, distinct and well-defined structures were observed in the presence of TMF. By controlling LPP parameters, the surface structuring of Mg alloy can be controlled. The optimization and enhancement of LPP parameters make it a highly useful tool for thin film deposition, coatings of multilayers, and ion implantation/doping.