Oxygen and water vapor gas barrier poly(ethylene naphthalate) films by deposition of SiOx plasma polymers from mixture of tetramethoxysilane and oxygen

SiO_x films were deposited from a mixture of tetramethoxysilane (TMOS) and oxygen on poly(ethylene 2,6‐naphthalate) film using ion‐assisted plasma polymerization technique (Method II) and conventional plasma polymerization technique (Method I), and were compared in chemical composition and gas barrier properties. Methods I and II were different in electrical circuit between electrodes (anode and cathode) and electric power supply. In Method I, the anode electrode was grounded, and the cathode electrode was coupled to the discharge power supply. In Method II, the anode electrode was connected with the discharge power supply, and the cathode electrode was grounded. There was not large difference in SiO_x deposition rate between the plasma polymerizations by Methods I and II. Plasma polymers deposited from TMOS/O₂ mixtures by Method II possessed smaller C/Si and O/Si atomic ratios than those deposited by Method I and showed advantage in gas barrier properties. The oxygen and water vapor permeation rates were 0.08–0.13 cm³ m^?2 day^?1 atm^?1 at 30°C at 90% RH and 0.244–0.276 g m^?2 day^?1 at 40°C at 90% RH, respectively. From these results, it can be concluded that the ion‐assisted plasma polymerization is a useful technique for deposition of gas barrier SiO_x thin films. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 915–925, 2007     

Characterization of Yb2SiO5-based environmental barrier coating prepared by plasma spray–physical vapor deposition

Due to the high-input power compared to atmospheric plasma spraying (APS), plasma spray-physical vapor deposition (PS-PVD) can primarily achieve a splat-like deposition, allowing for the preparation of high-density environmental barrier coatings (EBCs). In this paper, dense Yb₂SiO₅-based coatings are prepared by PS-PVD at different substrate temperatures. It was found that the coating deposited at the substrate temperature of 700 °C contained a large amount of silicon-rich amorphous phase. When the substrate temperature increased to 1100 °C and a slow cooling process after deposition was involved, a coating with high crystallinity of ～77% and low porosity of less than ～2% was achieved. Phase evolution of the coatings was studied by a semi-in-situ high-temperature X-ray diffractometer. During the heating process, metastable phases X1-Yb₂SiO₅ and α-Yb₂Si₂O₇ emerged and transformed into stable phases following high-temperature treatment. Furthermore, the effects of long-term thermal aging at 1300 °C on the microstructure, phase composition, thermal conductivity, and hardness of the coating prepared at the substrate temperature of 1100 °C were found to be limited.     

Adhesion of extrusion‐coated polymer sealing layers to a fiber‐based packaging material with an atomic layer deposited aluminum oxide surface coating

Adhesion of extrusion‐coated polymer sealing layers on an atomic layer deposited (ALD) aluminum oxide (Al₂O₃) surface coating was investigated with a view to gain information on the applicability of ALD deposited barrier layers in fiber‐based packaging materials. The polymers used for the sealing layer were low density polyethylene (LDPE), polyethylene terephthalate (PET), and polylactide (PLA). They were extrusion‐coated onto the ceramic side of paper/PET/Al₂O₃ substrates, where the Al₂O₃ layer was a few tens of nanometers thick. According to the results, good adhesion was obtained for LDPE coating, whereas the other coatings showed a considerable lack of adhesion. Presumably, the oxidation faced by LDPE in the air gap of the extrusion‐coating process was able to create an extensive number of reactive sites that strongly bonded with the hydroxyl groups on the oxide surface of the substrate. With the PET and PLA coatings, such oxidation did not occur and the adhesion obtained remained at a relatively poor level. With all of the coatings, the adhesion levels were improved using corona discharge equipment as a pretreatment prior to the extrusion‐coating process. POLYM. ENG. SCI., 52:1985–1990, 2012. © 2012 Society of Plastics Engineers     

Intentional Polymer Particle Contamination and the Simulation of Adhesion Failure due to Transit Scratches in Ultra-thin Solar Control Coatings on Glass

The major in-service failure mechanism of modern solar control coatings for the architectural glass can be mechanical (e.g., scratch damage). Many of these coatings are multilayer structures of less than 100 nm thickness and different coating architectures are possible (i.e., different layer materials, thickness and stacking order). For high-performance solar control coatings deposited by physical vapour deposition processes the active layer is a thin silver coating (approx. 8 nm thick) surrounded by antireflection coatings (e.g., ZnO, SnO₂) and barrier layers (e.g., TiO _x N _y ). Scratches are often found during delivery of the coated glass (called transit scratches) and it has been determined that the cause of the scratches was the polymer balls sprayed onto the glass to separate sheets while in transportation. This study has developed a simulation test for the transit scratches and has determined that the adhesion of layers within the multilayer stack is critical in determining performance. To test the adhesion of the coatings, coated samples have been subjected to scratch tests using a range of indenters and the most visible damage has been characterised. Through-thickness cracks were observed and it was seen that the coating was stripped by the balls at the weakest point in the coating stack. Microanalysis reveals this weakest point to be the silver/zinc oxide interface in the materials analysed in this study.     

Plasma sprayed nanostructured GdPO4 thermal barrier coatings: Preparation microstructure and CMAS corrosion resistance

Nanostructured GdPO₄ thermal barrier coatings (TBCs) were prepared by air plasma spraying, and their phase structure evolution and microstructure variation due to calcium–magnesium–alumina–silicate (CMAS) attack have been investigated. The chemical composition of the coating is close to that of the agglomerated particles used for thermal spraying. Nanozones with porous structure are embedded in the coating microstructure, with a percentage of ~30%. CMAS corrosion tests indicated that nanostructured GdPO₄ coating is highly resistant to penetration by molten CMAS at 1250°C. Within 1 hour heat treatment duration, a continuous dense reaction layer forms on the coating surface, which are composed of P–Si apatite based on Ca_2+xGd_8?x(PO₄)_x(SiO₄)_6?xO₂, anorthite and spinel phases. This layer provides effective prevention against CMAS further infiltration into the coating. Prolonged heat treatment densifies the reaction layer but does not change its phase composition.     

Suppression of radiation‐induced oxidation of polymers by sputtered silicon oxide coating

Oxygen barrier coating on polymers was attempted to obtain polymeric composite materials with improved radiation resistance. Silicon oxide (SiO_1.6) films ranging from 120 to 240 nm thick were formed on polypropylene (PP) and polyethylene (PE) by radio frequency (RF) magnetron sputtering. Oxygen permeability after SiO_1.6 deposition was reduced significantly in all samples studied, indicating that silicon oxide is a useful gas barrier. The oxygen permeability coefficient of deposited films for PP was 1.7–2.2 × 10^?14 cm³‐cm/cm²/s/cmHg and that for PE was 2.8–4.8 × 10^?13 cm³‐cm/cm²/s/cmHg. We studied the effect of such films on the radiation resistance of polymers in the presence of oxygen by microscopic infrared (IR) absorption spectroscopy. Silicon oxide films 180 nm thick were deposited on the surfaces of PP and PE, and the formation of carbonyl groups after irradiation in air was measured as a function of depth from the surface. Results compared with those for uncoated PE and PP showed that the radiation‐induced polymer oxidation is dramatically suppressed by silicon oxide coating. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 186–190, 2002     

Advanced anticorrosive coatings prepared from electroactive epoxy–SiO2 hybrid nanocomposite materials

A series of electroactive epoxy/amino-SiO₂ nanocomposite materials containing conjugated segments of electroactive amino-capped aniline trimer (ACAT) unit were successfully prepared. First of all, the amino-modified silica (AMS) particles of ∼50 nm in diameter were synthesized by performing the conventional base-catalyzed sol–gel reactions of tetraethyl orthosilicate (TEOS) in the presence of (3-aminopropyl)-trimethoxysilane (APTES) molecules. Subsequently, the AMS nanoparticles were blended into the epoxy ring-opening polymerization reactions between amino-terminated aniline trimer (ACAT)/T-403 and DGEBA, leading to the formation of electroactive epoxy resin–silica hybrid nanocomposites (EES). Furthermore, the redox behavior of as-prepared EES materials was identified by the electrochemical cyclic voltammetry studies. It should be noted that the as-prepared electroactive hybrid materials in the form of coating on cold-rolled steel (CRS) electrode were found to be much superior in corrosion protection over those of non-electroactive epoxy (NEE) and electroactive epoxy (EE) materials based on a series of electrochemical corrosion measurements in saline. The possible mechanism for the advanced enhancement of corrosion protection of EES coatings on CRS electrode could be interpreted as follows: (1) electroactive epoxy coatings may act as physical barrier coating; (2) redox catalytic capabilities of ACAT units existed in electroactive epoxy may induce the formation of passive metal oxide layers on CRS electrode, as further evidenced by SEM and ESCA studies; (3) well-dispersed AMS nanoparticles in EES matrix could act as effective hinder to enhance the oxygen barrier property of electroactive epoxy matrix, the result could be demonstrated by gas permeability analysis (GPA). Electroactive epoxy/SiO₂ nanocomposites were identified by a series of electrochemical measurements such as corrosion potential (E_corr), polarization resistance (R_p), corrosion current (I_corr) and electrochemical impedance spectroscopy (EIS) studied in 5 wt% NaCl electrolyte.     

Deposition and Analysis of Al‐Rich c‐AlxTi1−xN Coating with Preferred Orientation

Metastable c‐Al_xT_1?xN is an important and well‐established hard coating in the tool industry. To improve the mechanical and thermal properties, Al‐rich c‐Al_xTi_1?xN coatings with controllable preferred crystal orientations were fabricated via low‐pressure chemical vapor deposition (LP‐CVD) in an industrial plant, using an AlCl₃–TiCl₄–NH₃–Ar–H₂ precursor system. The c‐Al_xTi_1?xN coatings with (100)‐ and (111)‐preferred orientations and average x values of 0.82 and 0.73, respectively, comprised c‐Al(Ti)N/c‐Ti(Al)N nanolamellae with average compositions of c‐Al_0.9Ti_0.1N/c‐Al_0.6Ti_0.4N and c‐Al_0.80Ti_0.20N/c‐Al_0.50Ti_0.50N; the average lamellar periods were 7.7 and 4.5 nm, respectively. High‐resolution transmission electron microscopy indicated that the c‐Al(Ti)N/c‐Ti(Al)N nanolamellae were modulated along the <100> direction, implying coherent spinodal decomposition of c‐Al_xTi_1?xN in the as‐deposited state. The hardness of the c‐Al_xTi_1?xN coatings varied from 33 to 36 GPa, depending on the (100)‐ or (111)‐preferred orientation. Residual stress measurements in the as‐deposited state showed tensile stress values of 1.8 and 4.6 GPa for the (100)‐ and (111)‐oriented c‐Al_xT_1?xN coatings, respectively. This stress may be generated by the difference in the thermal expansion coefficient of the c‐Al_xT_1?xN coating and the carbide substrate and by coherency stress in the c‐Al(Ti)N/c‐Ti(Al)N nanolamellae. In situ high‐temperature X‐Ray diffraction results revealed high thermal stability up to 1000°C.     

Investigation of the corrosion protection of SiOx-like oxide films deposited by plasma-enhanced chemical vapor deposition onto carbon steel

The paper reports on the corrosion behavior of carbon steel coated with thin SiO_x-like oxide films. The SiO_x-like coatings were deposited by plasma-enhanced chemical vapor deposition (PECVD) and their thickness was varied between 20 and 200 nm. The coated carbon steel interfaces were investigated for their corrosion protection efficiency when immersed in an aqueous saline solution of 3% NaCl. FTIR measurements and electrochemical impedance spectroscopy (EIS) experiments revealed that thin SiO_x-like coating layers (20 nm thick) do not prevent the carbon steel from corrosion, while thicker silica layers (d ≥ 100 nm) protect efficiently carbon steel interfaces in highly saline media with a protection efficiency of about 96% for a 200 nm thick coating.     

Oxygen barrier property of synthesized polyacrylate coatings containing inter-chain cross-linking architecture on PET film

A series of coatings which applied for improving the oxygen barrier property of polyethylene terephthalate (PET) film were prepared based on the copolymerization of methyl methacrylate, methyl acrylate, diallyl maleate, and maleic acid (MA). The chemical structures of the coatings were characterized by Fourier Transform Infrared spectrometer. The curing behavior was analyzed by differential scanning calorimetry. The oxygen permeability (Po₂) was measured by gas permeability tester . The molecular weight was investigated by gel permeation chromatography (GPC). Po₂ is inversely proportional to the oxygen barrier property that the decrease of Po₂ indicates the improvement of oxygen barrier property. The coating containing inter-chain cross-linking structure formed by the dehydration of carboxylic acid improves the oxygen barrier property of PET film greatly. With the increasing content of MA, the oxygen barrier capability of coated PET film is enhanced according to the Po₂ decreasing from 1.450 to 0.8956. The Po₂ of coated PET film is minimized by selecting N-methyl pyrrolidone as solvent for polymerization. The GPC results indicate that the oxygen barrier of novel coated PET film can be obtained when the weight average molecular weight (Mw) is up to the stipulated value.     

Deposition of HMDSO-based coatings on PET substrates using an atmospheric pressure dielectric barrier discharge

This paper presents results on the formation of coatings in an atmospheric pressure dielectric barrier discharge using hexamethyldisiloxane (HMDSO) as gaseous precursor. Plasma-polymerized films are deposited onto polyethylene terephthalate (PET) films using argon and argon/air mixtures as carrier gases. The chemical and physical properties of the obtained coatings are discussed in detail using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). FTIR and XPS results show that the composition of the gas phase and the chemical structure of the obtained coatings are clearly correlated. When pure argon is used as working gas, the film is polymeric with a structure close to [(CH₃)₂–Si–O]_n, which means that the deposited films resemble PDMS. However, if plasma-polymerization occurs in argon/air mixtures, the deposited film is silica-like containing only few carbon atoms. These dense SiO_x coatings generally exhibit high barrier properties, while pure HMDSO-derived films might be of importance for selective permeation. From this point of view, the capability of controlling the film composition by varying the operation conditions opens interesting perspectives.     

Understanding the Formation of Vertical Cracks in Solution Precursor Plasma Sprayed Yttria‐Stabilized Zirconia Coatings

Yttria‐stabilized zirconia (YSZ) deposition by the solution precursor plasma spraying (SPPS) route has been of interest for potential thermal barrier coating (TBC) applications. It has been surmised that realization of unique microstructural features like vertical cracks, nanosized pores and fine splats in the TBCs can significantly enhance coating durability and performance. However, satisfactory control over the YSZ coating microstructure has been elusive in the absence of an adequate understanding of the mechanism responsible for coating deposition in SPPS. This study demonstrates the ability to tailor microstructure of deposited YSZ coatings over a wide range, from nano‐porous coatings to a vertically cracked microstructure. Varying of precursor flow rate has been shown to dictate the pyrolysis events occurring in situ and, adopting this approach, YSZ coatings with widely varying microstructural features have been developed. The coatings have been characterized in detail and the observations correlated with in‐flight particle generation and splat formation. These studies also provide useful insights into the possible origin of vertical cracks in the coating for which a mechanism is proposed.     

Synthesis and anticorrosive properties of electroactive polyimide/SiO2 composites

In this study, a series of electroactive polyimide/SiO₂ (EPIS) composite materials containing conjugated segments of electroactive amino‐capped aniline trimer (AT) unit were successfully prepared. First of all, the amino‐modified silica (AMS) particles of ∼100 nm in diameter were synthesized by performing the conventional base‐catalyzed sol–gel reactions. Subsequently, the AMS nanoparticles were blending into the polymerization reactions between AT and 4,4′‐(4,4′‐isopropylidenediphenoxy)‐bis(phthalic anhydride), leading to the formation of EPIS composites. The as‐prepared EPIS materials in the form of coating on cold‐rolled steel (CRS) electrode were found to be much superior in corrosion protection over those of non‐electroactive polyimide and EPI materials based on a series of electrochemical corrosion measurements in saline. The significant enhancement in corrosion protection of EPIS coatings on CRS electrodes might probably be attributed to the redox catalytic property of organic EPI inducing the formation of passive metal oxide layer and the barrier property of well‐dispersed AMS nanoparticles existed in EPI matrix. POLYM. COMPOS., 35:617–625, 2014. © 2013 Society of Plastics Engineers     

Electrochemical behaviour of thin films deposited by plasma DBD torch on copper: An O2-diffusion barrier

In the field of corrosion protection, the research of environmentally friendly coating processes is one of the research topics. The use of gaseous atmospheric plasma, especially dielectric barrier discharge (DBD) plasma is an interesting way to rapidly form a thin protective coating. The aim of this work is to characterize the electrochemical behaviour of a SiO_xC_yN_z film, formed from different organosilicon precursors, in neutral corrosive environment on copper. The film morphology and composition were determined by transmission electron microscopy (TEM) observations and X-ray photoelectron spectroscopy (XPS). The electrochemical behaviour of the different treated copper was studied by stationary techniques and electrochemical impedance spectroscopy (EIS). With the same plasma parameter, the kind of organosilicon precursor determines the chemical stability of the coatings in water, then their protective properties. When the SiO₂-like structure contains a low carbon level, the SiO_xC_yN_z films present a good stability in water, and acts clearly as an O₂ barrier membrane.     

Electrochemical investigations on the corrosion protection effect of poly(vinyl carbazole)‐silica hybrid sol–gel materials

A series of sol–gel derived organic–inorganic hybrid coatings consisting of organic poly (vinyl carbazole) (PVK) and inorganic silica (SiO₂), with 3‐(trimethoxysilyl)propyl methacrylate (MSMA) as coupling agent, were successfully synthesized. First of all, vinyl carbazole (VCz) monomers are copolymerized with MSMA by performing free‐radical polymerization reactions with AIBN as initiator. Subsequently, as‐prepared copolymer (i.e., sol–gel precursor) was further reacted with various feeding content of tetraethyl orthosilicate (TEOS) through organic acid (CSA)‐catalyzed sol–gel reaction to form a series of PVK‐silica hybrid (PSH) sol–gel materials. The as‐synthesized hybrid materials were subsequently characterized by Fourier‐Transformation infrared (FTIR) spectroscopy and solid‐state ²⁹Si NMR. It should be noted that the PVK‐SiO₂ hybrid (PSH) coating on cold‐rolled steel (CRS) electrode with low silica loading (e.g., 10 phr) was found to be superior in anticorrosion property over those of neat PVK based on a series of electrochemical measurements such as corrosion potential, polarization resistance, corrosion current, and electrochemical impedance spectroscopy in 3.5 wt% NaCl electrolyte. The better anticorrosion performance of PSH coatings as compared to that of neat polymer may probably be attributed to the stronger adhesion strength of PSH coatings on CRS electrode, which was further evidenced by Scotch tape test evaluation. Increase of adhesion strength of PSH coatings on CRS electrode may be associated with the formation of Fe–O–Si covalent bonds at the interface of PSH coating and CRS electrode based on the FTIR–RAS (reflection absorption spectroscopy) studies. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Deposition of graded SiO2/SiC coatings using high-velocity solution plasma spray

Carbon/carbon (C/C) composites are widely used in structural components, particularly in the aerospace and aeronautics sectors. However, the application of C/C composites is limited by low oxidation resistance at high temperatures. In order to overcome this problem, graded SiO₂/SiC coatings were deposited on C/C composites by a high-velocity solution plasma spray (HVSPS) process. Graded coatings were formed by reactions between the Si(OH)₄ sprayed liquid precursor and the C/C substrate; these reactions were promoted by the high temperature of the plasma torch. The morphologies, microstructures, and chemical compositions of the coatings were investigated by X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, and scanning electron microscopy/energy-dispersive X-ray spectroscopy. By altering the deposition time, the coating thickness was controlled, therefore demonstrating SiC formation and realizing graded SiO₂/SiC coatings.     

New formation process of plating thin films on several substrates by means of self-assembled monolayer (SAM) process

This review describes our recent works on the preparation of Ni-alloy films deposited by electroless deposition as a diffusion barrier layer for ultra large-scale integration (ULSI) interconnects by using an all-wet process.In this process, we create a novel wet fabrication process including a self-assembled monolayer (SAM) as an attachment technique between diffusion barrier layer and a substrate. Our proposal process was applied to the substrates of SiO₂/Si and both organic (methyl silsesquioxane) and inorganic (hydrogen silsesquioxane) low-k dielectrics. The key technique of this proposed process is using SAM as a catalyst trapping layer. The Ni-alloy films such as NiB were deposited on catalyzed SiO₂ or low-k substrates. The electrolessly deposited NiB films were found to exhibit sufficient thermal stability and an acceptable barrier property for preventing Cu diffusion into the SiO₂ and low-k dielectrics.     

Development of antibacterial silver treatments on HDPE nets for agriculture

The defense mechanism of crops associated with the use of polymeric nets and fabrics is only physical and, hence, ineffective against the bacterial contaminations. The presence of an antibacterial agent associated with the use of conventional agro‐textiles can represent a great advantage in the prevention of plant diseases and for food safety. The aim of this work was the development of antibacterial silver‐coated HDPE nets for an innovative application such as agriculture. Antibacterial coatings on high‐density polyethylene nets were obtained by a patented nanosilver deposition technique based on the in situ photo‐reduction of a silver solution. The concentration of silver deposited was defined by testing different silver solutions from a biological point of view. Moreover, in order to improve the adhesion of the silver coating to the substrate, the nets underwent low‐pressure plasma treatment before the silver deposition. The materials were characterized in terms of quality of the coating through scanning electron microscopy, and in terms of antibacterial capability on Gram positive and Gram negative bacteria through qualitative and quantitative microbiological tests. The most effective process parameters were defined and the importance of performing plasma pretreatment on this specific substrate was assessed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41623.     

Electrochemical investigation of the influence of thin SiOx films deposited on gold on charge transfer characteristics

The paper reports on the investigation of the electrochemical behavior of a thin gold film electrode coated with silicon dioxide (SiO_x) layers of increasing thickness. Stable thin films of amorphous silica (SiO_x) were deposited on glass slides coated with a 5 nm adhesion layer of titanium and 50 nm of gold, using plasma-enhanced chemical vapor deposition (PECVD) technique. Scanning electrochemical microscopy (SECM) and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical behavior of the interfaces. In the case of SECM, the influence of the SiO_x thicknesses on the electron transfer kinetics of three redox mediators was investigated. Normalized current-distance curves (approach curves) were fitted to the theoretical model in order to find the effective heterogeneous first order rate constant (k_eff) at the sample. EIS was in addition used to confirm the diffusion barrier character of the SiO_x interlayer.     

Surface modification of silicone rubber by ion beam assisted deposition (IBAD) for improved biocompatibility

We studied the preparation of antimicrobial silicone rubbers of improved interfacial strength, which could be formed with the ion beam assisted deposition (IBAD) technique for coating metallic or inorganic materials (silver (Ag), Copper (Cu), and Hydroxyapatite(HAp)/TiO₂) on the silicone surface. Those coating materials provide high product safety as well as outstanding antimicrobial activity. The deposition methodology is composed of pre‐etching with oxygen gas, vaporizing the coating materials, and post‐treatment with Ar ion. With the evaporation of the coating materials, the Ar beam was focused on the substrate to assist deposition. It was found out that the ion assisting depositions in the IBAD process give a prominent enhancement in adhesion between silicone rubbers and coatings of Ag and Cu. The HAp/TiO₂ coating layer was easily dissolved in aqueous saline solution. All deposited layers display high antimicrobial activities against Staphlococcus aureus (ATCC 6538) and Escherichia coil (ATCC 25,922), showing 99.9% reduction of bacteria, respectively. In a cytotoxicity test, the Ag and HAp/TiO₂ coated silicone shows a decrease of cytotoxicity, while the Cu coating leads to a slight increase of cytotoxicity. The result on the surface modifications of silicone rubber will be employed in further study for applications of medical or rehabilitation devices. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1095–1101, 2005