Coatings

3840 KiB

Open AccessCommunication

Local Electrical Response in Alkaline-Doped Electrodeposited CuInSe₂/Cu Films

by Javier A. Barón-Miranda, Octavio Calzadilla, Liliana E. Arvizu-Rodríguez, Jose L. Fernández-Muñoz, Cesia Guarneros-Aguilar, Fabio Chale-Lara, Ulises Páramo-García and Felipe Caballero-Briones

Coatings 2016, 6(4), 71; https://doi.org/10.3390/coatings6040071 - 20 Dec 2016

Cited by 2 | Viewed by 5647

Abstract

The local electrical response in alkaline-doped CuInSe₂ films prepared by single-step electrodeposition onto Cu substrates was studied by current-sensing atomic force microscopy. The CuInSe₂ (CIS) films were prepared from single baths containing the dopant ions (Li, Na, K or Cs) and [...] Read more.

The local electrical response in alkaline-doped CuInSe₂ films prepared by single-step electrodeposition onto Cu substrates was studied by current-sensing atomic force microscopy. The CuInSe₂ (CIS) films were prepared from single baths containing the dopant ions (Li, Na, K or Cs) and were studied by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and photocurrent response. Increased crystallinity and surface texturing as the ion size increased were observed, as well as an enhanced photocurrent response in Cs-doped CIS. Li- and Na-doped films had larger conductivity than the undoped film while the K- and Cs-doped samples displayed shorter currents and the current images indicated strong charge accumulation in the K- and Cs-doped films, forming surface capacitors. Corrected current-sensing AFM IV curves were adjusted with the Shockley equation. Full article

(This article belongs to the Special Issue Thin Films and Patterned Structures by Electrochemical Methods)

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17297 KiB

Open AccessArticle

Durability Analysis and Experimental Validation of Environmental Barrier Coating (EBC) Performance Using Combined Digital Image Correlation and NDE

by Ali Abdul-Aziz and Adam C. Wroblewski

Coatings 2016, 6(4), 70; https://doi.org/10.3390/coatings6040070 - 16 Dec 2016

Cited by 8 | Viewed by 6424

Abstract

To understand the failure mechanism or to predict the spallation life of environmental barrier coatings (EBC) on fiber reinforced ceramic matrix composites, the fracture strength of EBC and the process of the crack growth in EBC layers need to be experimentally determined under [...] Read more.

To understand the failure mechanism or to predict the spallation life of environmental barrier coatings (EBC) on fiber reinforced ceramic matrix composites, the fracture strength of EBC and the process of the crack growth in EBC layers need to be experimentally determined under standard or simulated engine operating conditions. The current work considers a multi layered barium strontium aluminum silicate (BSAS)-based EBC-coated, melt infiltrated silicon carbide fiber reinforced silicon carbide matrix composite (MI SiC/SiC) specimen that was tensile tested at room temperature. Numerous tests were performed under tensile loading conditions, and the specimen was loaded until failure under pre-determined stress levels. The specimen was examined with optical microscopy, scanning electron microscopy (SEM), computed tomography (CT) scan, and digital image correlation (DIC) camera. Observation from the computed tomography scanning, the SEM, and the optical microscopy did not offer conclusive information concerning the cracks that spawned during the tests. However, inspection with the DIC camera offered some indication that cracks had developed and allowed their detection and the location of their initiation site. Thus, this study provides detailed discussion of the results obtained from the experimental investigation and the nondestructive evaluation (NDE), and it also includes assessment of the stress response predicted by analytical modeling and their impact on EBC durability and crack growth formation under complex loading settings. Full article

(This article belongs to the Special Issue Five Years of Coatings: Coatings Science and Technology for the 21st Century)

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137 KiB

Open AccessErratum

Erratum: Panagopoulos, C.N., et al. Wear Behaviour of Nanostructured Polymer-Based Safety Films on Soda-Lime Glass. Coatings 2016, 6, 26

by C. N. Panagopoulos, E. P. Georgiou, G. S. Tradas and K. I. Giannakopoulos

Coatings 2016, 6(4), 69; https://doi.org/10.3390/coatings6040069 - 14 Dec 2016

Viewed by 3262

Abstract

n/a Full article

(This article belongs to the Special Issue Five Years of Coatings: Coatings Science and Technology for the 21st Century)

3303 KiB

Open AccessArticle

Characterization and Photovoltaic Properties of BiFeO₃ Thin Films

by Yasuhiro Shirahata and Takeo Oku

Coatings 2016, 6(4), 68; https://doi.org/10.3390/coatings6040068 - 08 Dec 2016

Cited by 18 | Viewed by 7231

Abstract

Bismuth ferrite (BiFeO₃) thin films were prepared by a spin-coating method. Crystal structure and optical properties of the BiFeO₃ films were evaluated using X-ray diffraction. The lattice constants, crystallite size, and energy gap of BiFeO₃ films depended on the [...] Read more.

Bismuth ferrite (BiFeO₃) thin films were prepared by a spin-coating method. Crystal structure and optical properties of the BiFeO₃ films were evaluated using X-ray diffraction. The lattice constants, crystallite size, and energy gap of BiFeO₃ films depended on the concentration of the BiFeO₃ precursor solution. BiFeO₃/CH₃NH₃PbI₃ photovoltaic devices were fabricated to investigate photovoltaic properties of BiFeO₃. Current density–voltage characteristics of the photovoltaic devices showed rectifying behavior, indicating that BiFeO₃ worked as an electron transport layer in CH₃NH₃PbI₃-based photovoltaic devices. Full article

(This article belongs to the Special Issue Five Years of Coatings: Coatings Science and Technology for the 21st Century)

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6506 KiB

Open AccessArticle

The Microstructure and Wear Resistance of a Copper Matrix Composite Layer on Copper via Nitrogen-Shielded Arc Cladding

by Yinan Li, Xianbao Liu, Zhikang Zhou, Lei Zhang and Zilong Peng

Coatings 2016, 6(4), 67; https://doi.org/10.3390/coatings6040067 - 06 Dec 2016

Cited by 6 | Viewed by 5270

Abstract

A TiN and TiN·Ti₂Cu reinforced copper matrix composite layer was cladded onto a T3 copper substrate to improve the anti-wear performance of copper products by means of the nitrogen-shielded gas tungsten arc cladding method (N₂-GTAC). Better than the traditional [...] Read more.

A TiN and TiN·Ti₂Cu reinforced copper matrix composite layer was cladded onto a T3 copper substrate to improve the anti-wear performance of copper products by means of the nitrogen-shielded gas tungsten arc cladding method (N₂-GTAC). Better than the traditional preparation method of TiN, the TiN particles in the cladding layer were in situ generated using N atoms of shielding gas and Ti atoms of pre-deposited metal powders. In addition, the composite phase TiN·Ti₂Cu occurred in the cladding layer, which also had a positive effect on anti-wearing. As Ti increased, the amount and grain size of TiN·Ti₂Cu and TiN increased as a result. The hardness of the cladding layer increased with the increasing amount of reinforced phase generated in the layer. The hardness of the layer reached a maximum of 410 HV, which is nearly 5.1 times greater than that of copper. The TiN·Ti₂Cu- and TiN-reinforced phases improved the wear resistance of the cladding layers. The cladding layer with 15 wt % Ti had the longsest launch stage (600 s) and the lowest fiction coefficient (0.56). Full article

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4740 KiB

Open AccessArticle

Improving the Performance of Clear Coatings on Wood through the Aggregation of Marginal Gains

by Philip D. Evans, Stephan Vollmer, Joseph Doh Wook Kim, George Chan and Sara Kraushaar Gibson

Coatings 2016, 6(4), 66; https://doi.org/10.3390/coatings6040066 - 26 Nov 2016

Cited by 19 | Viewed by 10250

Abstract

Remarkable increases in the performance of complex systems can be achieved by a collective approach to optimizing individual factors that influence performance. This approach, termed the aggregation of marginal gains, is tested here as a means of improving the performance of exterior clear-coatings. [...] Read more.

Remarkable increases in the performance of complex systems can be achieved by a collective approach to optimizing individual factors that influence performance. This approach, termed the aggregation of marginal gains, is tested here as a means of improving the performance of exterior clear-coatings. We focused on five factors that influence clear-coating performance: dimensional stability of wood; photostability of the wood surface; moisture ingress via end-grain; coating flexibility and photostability; and finally coating thickness. We performed preliminary research to select effective wood pre-treatments and durable clear-coatings, and then tested coating systems with good solutions to each of the aforementioned issues (factors). Red oak and radiata pine panels were modified with PF-resin, end-sealed, and thick acrylic, alkyd or spar varnishes were applied to the panels. Panels were exposed to the weather and the level of coating defects was assessed every year over a 4-year period. All of the coatings are performing well on PF-modified pine after 4 years’ outdoor exposure. In contrast, coatings failed after 2 years on unmodified pine and they are failing on PF-modified oak. We conclude that our approach shows promise. Future research will build on the current work by developing solutions to additional factors that influence clear-coating performance. Full article

(This article belongs to the Special Issue Five Years of Coatings: Coatings Science and Technology for the 21st Century)

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10728 KiB

Open AccessArticle

Corrosion Testing of Thermal Spray Coatings in a Biomass Co-Firing Power Plant

by Maria Oksa, Jarkko Metsäjoki and Janne Kärki

Coatings 2016, 6(4), 65; https://doi.org/10.3390/coatings6040065 - 24 Nov 2016

Cited by 12 | Viewed by 7427

Abstract

Large-scale use of biomass and recycled fuel is increasing in energy production due to climate and energy targets. A 40% cut in greenhouse gas emission compared to 1990 levels and at least a 27% share of renewable energy consumption are set in EU [...] Read more.

Large-scale use of biomass and recycled fuel is increasing in energy production due to climate and energy targets. A 40% cut in greenhouse gas emission compared to 1990 levels and at least a 27% share of renewable energy consumption are set in EU Energy Strategy 2030. Burning fuels with high content of corrosive species such as chlorine and heavy metals causes deterioration of boiler components, shortened lifetime, limited availability of a plant and hence higher maintenance and investment costs and lower thermal and economic efficiency. Coatings can be applied to protect the critical boiler components against high temperature corrosion. In this study, five thermal spray coatings were tested in an actual biomass co-firing boiler for 1300 h with a measurement probe. The coatings were analyzed after the exposure by metallographic means and scanning electron microscope/energy-dispersive X-ray spectroscope (SEM/EDX). The deposits formed on the specimens were analyzed by X-ray fluorescence. At 550 °C, the coatings showed excellent corrosion performance compared to reference material ferritic steel T92. At 750 °C, tube material A263 together with NiCr and NiCrTi had the highest corrosion resistance. To conclude, thermal spray coatings can offer substantial corrosion protection in biomass and recycled fuel burning power plants. Full article

(This article belongs to the Special Issue Five Years of Coatings: Coatings Science and Technology for the 21st Century)

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Open AccessArticle

Structural Study of Silica Coating Thin Layers Prepared from Perhydropolysilazane: Substrate Dependence and Water Penetration Structure

by Tomotake Niizeki, Sachiko Nagayama, Yoshio Hasegawa, Noboru Miyata, Masae Sahara and Kazuhiro Akutsu

Coatings 2016, 6(4), 64; https://doi.org/10.3390/coatings6040064 - 19 Nov 2016

Cited by 14 | Viewed by 7690

Abstract

The structure of perhydropolysilazane (PHPS)-derived silica (PDS) waterproof thin layers synthesized by curing at 60 °C for 1 h and allowed to stand for 48 h at 20 °C on various kinds of substrates was studied. Neutron reflectivity (NR) analysis suggested that uniform [...] Read more.

The structure of perhydropolysilazane (PHPS)-derived silica (PDS) waterproof thin layers synthesized by curing at 60 °C for 1 h and allowed to stand for 48 h at 20 °C on various kinds of substrates was studied. Neutron reflectivity (NR) analysis suggested that uniform PDS thin layers were synthesized on the substrates, and the density of the layers varied depending on the type of substrate. Additionally, since the change in PDS density is correlated with the pK_a value of the OH group on the substrate, it can be suggested that the acidity of the substrate would be one of the main factors determining the density of the coated PDS thin layers. For the water penetration structure study, NR analysis revealed that the depth of water penetration into the PDS layers was below 500 Å, and the hydration number of the SiO₂ molecule was estimated to be 8.0–9.0. From these results, we concluded that water penetration occurred by the formation of water-pool structures in the PDS layers, and the randomly formed nano-air holes lead to a reduction in the probability of water penetration into the deep regions of the PDS layers. Full article

(This article belongs to the Special Issue Advances in Coatings Characterization)

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2943 KiB

Open AccessArticle

Fabrication of Microalloy Nitrided Layer on Low Carbon Steel by Nitriding Combined with Surface Nano-Alloying Pretreatment

by Jian Sun and Quantong Yao

Coatings 2016, 6(4), 63; https://doi.org/10.3390/coatings6040063 - 17 Nov 2016

Cited by 5 | Viewed by 5692

Abstract

Surface mechanical attrition treatment (SMAT) is an effective method to accelerate the nitriding process of metallic materials. In this work, a novel technique named surface nano-alloying (SNA) was developed on the basis of surface mechanical attrition treatment, which was employed as a pretreatment [...] Read more.

Surface mechanical attrition treatment (SMAT) is an effective method to accelerate the nitriding process of metallic materials. In this work, a novel technique named surface nano-alloying (SNA) was developed on the basis of surface mechanical attrition treatment, which was employed as a pretreatment for the nitriding of low carbon steel materials. The microstructure and surface properties of treated samples were investigated by SEM, XRD, TEM and the Vickers hardness test. Experimental results showed that a surface alloying layer (Cr element) of about 10–20 μm in thickness was formed on the low carbon steel sample after the surface nano-alloying treatment. After nitriding for the SNA sample, a complex compound layer composed of Fe_2–3N, FeCr and Cr₂N phases was fabricated. Moreover, the thickness of this compound layer was about 50 μm. Meanwhile, both the surface hardness and wear resistance of the SNA nitrided sample are better that those of the SMAT nitrided sample. This work offers a new approach for improving the nitriding process of steel materials. Full article

(This article belongs to the Special Issue Surface Chemical Modification)

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5533 KiB

Open AccessArticle

Influence of Surface Roughness and Agitation on the Morphology of Magnetite Films Electrodeposited on Carbon Steel Substrates

by Soon-Hyeok Jeon, Won-Ik Choi, Geun-Dong Song, Yeong-Ho Son and Do Haeng Hur

Coatings 2016, 6(4), 62; https://doi.org/10.3390/coatings6040062 - 16 Nov 2016

Cited by 20 | Viewed by 8265

Abstract

In this work, we investigated the effects of surface roughness and agitation on the morphology of magnetite films electrodeposited from alkaline Fe(III)-triethanolamine (TEA) solutions on carbon steel substrates. The surface roughness of the carbon steel substrates was maintained in the range of 1.64–0.06 [...] Read more.

In this work, we investigated the effects of surface roughness and agitation on the morphology of magnetite films electrodeposited from alkaline Fe(III)-triethanolamine (TEA) solutions on carbon steel substrates. The surface roughness of the carbon steel substrates was maintained in the range of 1.64–0.06 μm by using mechanical grinding and polishing methods. The agitation speed was set at 0 and 900 rpm during the electrodeposition process. The particle size and surface roughness value of the magnetite films gradually decreased with decreasing substrate roughness. However, the influence of the substrate roughness on the thickness of the magnetite film was negligible. The morphology of the magnetite film fabricated at 900 rpm appeared to be highly faceted compared to that of the magnetite film produced at 0 rpm. The thickness and surface roughness of the magnetite film significantly increased with the agitation speed, which also significantly affected the electrodeposition efficiency. The effects of substrate surface roughness and agitation on the morphology of magnetite films electrodeposited on carbon steel substrates were also discussed. The obtained results provide critical information for the simulation of magnetite deposits on carbon steel pipes in the secondary systems of nuclear power plants. Full article

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Open AccessArticle

Development of Mirror Coatings for Gravitational Wave Detectors

by Stuart Reid and Iain W. Martin

Coatings 2016, 6(4), 61; https://doi.org/10.3390/coatings6040061 - 16 Nov 2016

Cited by 30 | Viewed by 8578

Abstract

The first detections of gravitational waves, GW150914 and GW151226, were associated with the coalescence of stellar mass black holes, heralding the opening of an entirely new way to observe the Universe. Many decades of development were invested to achieve the sensitivities required to [...] Read more.

The first detections of gravitational waves, GW150914 and GW151226, were associated with the coalescence of stellar mass black holes, heralding the opening of an entirely new way to observe the Universe. Many decades of development were invested to achieve the sensitivities required to observe gravitational waves, with peak strains associated with GW150914 at the level of 10⁻²¹. Gravitational wave detectors currently operate as modified Michelson interferometers, where thermal noise associated with the highly reflective mirror coatings sets a critical limit to the sensitivity of current and future instruments. This article presents an overview of the mirror coating development relevant to gravitational wave detection and the prospective for future developments in the field. Full article

(This article belongs to the Special Issue Recent Advances in Optical Coatings)

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4849 KiB

Open AccessArticle

Performances and Coating Morphology of a Siloxane-Based Hydrophobic Product Applied in Different Concentrations on a Highly Porous Stone

by Mariateresa Lettieri and Maurizio Masieri

Coatings 2016, 6(4), 60; https://doi.org/10.3390/coatings6040060 - 13 Nov 2016

Cited by 20 | Viewed by 5990

Abstract

Many polymers, able to confer a hydrophobicity to treated surfaces, have been proposed for the restoration and conservation of civil and monumental buildings. Polysiloxanes, and their precursors, the silanes, have been frequently employed for stone protection. To avoid decay of the treated surfaces, [...] Read more.

Many polymers, able to confer a hydrophobicity to treated surfaces, have been proposed for the restoration and conservation of civil and monumental buildings. Polysiloxanes, and their precursors, the silanes, have been frequently employed for stone protection. To avoid decay of the treated surfaces, the effectiveness and harmlessness of the treatment need to be carefully evaluated before application in the field. In this study, a commercial alkyl-siloxane was tested as a protective treatment on a highly porous stone, starting from water solutions with different contents of the product. The treatments have been devised to try to balance the requirements and the sustainability of the conservative actions. Sustainability, in terms of costs and environmental impact, is regarded as a key factor in the 21st century. Morphological observations of the stone surface, static contact angle and colour measurements, water vapour transmission test, and tests of water absorption were carried out to characterize the untreated and treated stones. A concentration below the minimum level suggested by the manufacturer was still able to act as a good barrier against water. More concentrated solutions produced polymer accumulation and coatings with extended cracks. The properties of the treated stone were affected by the presence of cracks in the coating. Full article

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3836 KiB

Open AccessCommunication

Cylindrical Three-Dimensional Porous Anodic Alumina Networks

by Pedro M. Resende, Ruy Sanz, Alejandra Ruiz-de Clavijo, Olga Caballero-Calero and Marisol Martin-Gonzalez

Coatings 2016, 6(4), 59; https://doi.org/10.3390/coatings6040059 - 09 Nov 2016

Cited by 9 | Viewed by 4789

Abstract

The synthesis of a conformal three-dimensional nanostructure based on porous anodic alumina with transversal nanopores on wires is herein presented. The resulting three-dimensional network exhibits the same nanostructure as that obtained on planar geometries, but with a macroscopic cylindrical geometry. The morphological analysis [...] Read more.

The synthesis of a conformal three-dimensional nanostructure based on porous anodic alumina with transversal nanopores on wires is herein presented. The resulting three-dimensional network exhibits the same nanostructure as that obtained on planar geometries, but with a macroscopic cylindrical geometry. The morphological analysis of the nanostructure revealed the effects of the initial defects on the aluminum surface and the mechanical strains on the integrity of the three-dimensional network. The results evidence the feasibility of obtaining 3D porous anodic alumina on non-planar aluminum substrates. Full article

(This article belongs to the Special Issue Advances in Coatings Characterization)

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Open AccessArticle

Thermally Sprayed Aluminum Coatings for the Protection of Subsea Risers and Pipelines Carrying Hot Fluids

by Nataly Ce and Shiladitya Paul

Coatings 2016, 6(4), 58; https://doi.org/10.3390/coatings6040058 - 08 Nov 2016

Cited by 15 | Viewed by 6788

Abstract

This paper reports the effect of boiling synthetic seawater on the performance of damaged Thermally Sprayed Aluminum (TSA) on carbon steel. Small defects (4% of the sample’s geometric surface area) were drilled, exposing the steel, and the performance of the coating was analyzed [...] Read more.

This paper reports the effect of boiling synthetic seawater on the performance of damaged Thermally Sprayed Aluminum (TSA) on carbon steel. Small defects (4% of the sample’s geometric surface area) were drilled, exposing the steel, and the performance of the coating was analyzed for corrosion potential for different exposure times (2 h, 335 h, and 5000 h). The samples were monitored using linear polarization resistance (LPR) in order to obtain their corrosion rate. Scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) were used for post-test characterization. The results showed that a protective layer of Mg(OH)₂ formed in the damaged area, which protected the underlying steel. Additionally, no coating detachment from the steel near the defect region was observed. The corrosion rate was found to be 0.010–0.015 mm/year after 5000 h in boiling synthetic seawater. Full article

(This article belongs to the Special Issue Five Years of Coatings: Coatings Science and Technology for the 21st Century)

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5280 KiB

Open AccessArticle

Statistical Contact Angle Analyses with the High-Precision Drop Shape Analysis (HPDSA) Approach: Basic Principles and Applications

by Florian Heib and Michael Schmitt

Coatings 2016, 6(4), 57; https://doi.org/10.3390/coatings6040057 - 06 Nov 2016

Cited by 74 | Viewed by 14178

Abstract

Surface science, which includes the preparation, development and analysis of surfaces and coatings, is essential in both fundamental and applied as well as in engineering and industrial research. Contact angle measurements using sessile drop techniques are commonly used to characterize coated surfaces or [...] Read more.

Surface science, which includes the preparation, development and analysis of surfaces and coatings, is essential in both fundamental and applied as well as in engineering and industrial research. Contact angle measurements using sessile drop techniques are commonly used to characterize coated surfaces or surface modifications. Well-defined surfaces structures at both nanoscopic and microscopic level can be achieved but the reliable characterization by means of contact angle measurements and their interpretation often remains an open question. Thus, we focused our research effort on one main problem of surface science community, which is the determination of correct and valid definitions and measurements of contact angles. In this regard, we developed the high-precision drop shape analysis (HPDSA), which involves a complex transformation of images from sessile drop experiments to Cartesian coordinates and opens up the possibility of a physically meaningful contact angle calculation. To fulfill the dire need for a reproducible contact angle determination/definition, we developed three easily adaptable statistical analyses procedures. In the following, the basic principles of HPDSA will be explained and applications of HPDSA will be illustrated. Thereby, the unique potential of this analysis approach will be illustrated by means of selected examples. Full article

(This article belongs to the Special Issue Advances in Coatings Characterization)

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3374 KiB

Open AccessArticle

Emulsion Polymerization of Tung Oil-Based Latexes with Asolectin as a Biorenewable Surfactant

by Ashley Johns, Kyle Edwards, Sarah Inglesby and Rafael L. Quirino

Coatings 2016, 6(4), 56; https://doi.org/10.3390/coatings6040056 - 04 Nov 2016

Cited by 2 | Viewed by 5651

Abstract

Bio-based vesicles, with potential application in drug delivery and/or catalyst encapsulation, have been prepared by the free radical emulsion co-polymerization of tung oil, divinylbenzene (DVB), n-butyl methacrylate (BMA), and asolectin in a xylene/water mixture. The free radical polymerization was initiated by di- [...] Read more.

Bio-based vesicles, with potential application in drug delivery and/or catalyst encapsulation, have been prepared by the free radical emulsion co-polymerization of tung oil, divinylbenzene (DVB), n-butyl methacrylate (BMA), and asolectin in a xylene/water mixture. The free radical polymerization was initiated by di-tert-butyl peroxide (DTBP) at 100 °C in a convection oven. Molecular weights of approximately 11,000 Da were measured by Matrix-assisted Laser Desorption/Ionization-Time of Flight (Maldi-TOF) for tung oil-asolectin copolymers, verifying that significant polymerization occurs under the cure conditions employed. The cure of the co-monomer mixture employed in this work was monitored by Dielectric Analysis (DEA), while changes in the Raman spectrum of all co-monomers before and after the cure, along with differential scanning calorimetry (DSC) analysis, have been used to verify the need of a post-cure step and completion of the polymerization reaction. Scanning Transmission Electron Microscopy (STEM) images of the emulsion after polymerization indicate that vesicles were formed, and vesicle size distribution of samples prepared with different amounts of tung oil were determined using a Zetasizer. Full article

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1574 KiB

Open AccessArticle

Cellular Automata Modelling of Photo-Induced Oxidation Processes in Molecularly Doped Polymers

by David M. Goldie

Coatings 2016, 6(4), 55; https://doi.org/10.3390/coatings6040055 - 04 Nov 2016

Cited by 1 | Viewed by 3866

Abstract

The possibility of employing cellular automata (CA) to model photo-induced oxidation processes in molecularly doped polymers is explored. It is demonstrated that the oxidation dynamics generated using CA models exhibit stretched-exponential behavior. This dynamical characteristic is in general agreement with an alternative analysis [...] Read more.

The possibility of employing cellular automata (CA) to model photo-induced oxidation processes in molecularly doped polymers is explored. It is demonstrated that the oxidation dynamics generated using CA models exhibit stretched-exponential behavior. This dynamical characteristic is in general agreement with an alternative analysis conducted using standard rate equations provided the molecular doping levels are sufficiently low to prohibit the presence of safe-sites which are impenetrable to dissolved oxygen. The CA models therefore offer the advantage of exploring the effect of dopant agglomeration which is difficult to assess from standard rate equation solutions. The influence of UV-induced bleaching or darkening upon the resulting oxidation dynamics may also be easily incorporated into the CA models and these optical effects are investigated for various photo-oxidation product scenarios. Output from the CA models is evaluated for experimental photo-oxidation data obtained from a series of hydrazone-doped polymers. Full article

(This article belongs to the Special Issue Five Years of Coatings: Coatings Science and Technology for the 21st Century)

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1450 KiB

Open AccessReview

Introduction to Advanced X-ray Diffraction Techniques for Polymeric Thin Films

by Nicodemus Edwin Widjonarko

Coatings 2016, 6(4), 54; https://doi.org/10.3390/coatings6040054 - 01 Nov 2016

Cited by 69 | Viewed by 21299

Abstract

X-ray diffraction has been a standard technique for investigating structural properties of materials. However, most common applications in the organic materials community have been restricted to either chemical identification or qualitative strain analysis. Moreover, its use for polymeric thin films has been challenging [...] Read more.

X-ray diffraction has been a standard technique for investigating structural properties of materials. However, most common applications in the organic materials community have been restricted to either chemical identification or qualitative strain analysis. Moreover, its use for polymeric thin films has been challenging because of the low structure factor of carbon and the thin film nature of the sample. Here, we provide a short review of advanced X-ray diffraction (XRD) techniques suitable for polymeric thin films, including the type of analysis that can be done and measurement geometries that would compensate low signals due to low carbon structure factor and the thin film nature of the sample. We will also briefly cover the

χ

-pole figure for texture analysis of ultra-thin film that has recently become commonly used. A brief review of XRD theory is also presented. Full article

(This article belongs to the Special Issue Polymer Thin Films)

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Open AccessArticle

Fullerene-Based Electron Transport Layers for Semi-Transparent MAPbBr₃ Perovskite Films in Planar Perovskite Solar Cells

by Lung-Chien Chen, Zong-Liang Tseng, Jun-Kai Huang, Cheng-Chiang Chen and Sheng Hsiung Chang

Coatings 2016, 6(4), 53; https://doi.org/10.3390/coatings6040053 - 28 Oct 2016

Cited by 15 | Viewed by 8024

Abstract

In this study, four kinds of structures—[6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM), PCBM/fullerene (C₆₀), C₆₀/bathocuproine (BCP), and PCBM/C₆₀/BCP—were used as electron transport layers, and the structure, and optical and electronic behaviors of MAPbBr₃ perovskite layers [...] Read more.

In this study, four kinds of structures—[6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM), PCBM/fullerene (C₆₀), C₆₀/bathocuproine (BCP), and PCBM/C₆₀/BCP—were used as electron transport layers, and the structure, and optical and electronic behaviors of MAPbBr₃ perovskite layers after annealing treatments were observed. The experimental results indicate that PCBM/C₆₀ bi-layer structure is acceptable for MAPbBr₃ planar perovskite solar cells due to electron step transporting. Low-temperature annealing is suitable for smooth and large grain MAPbBr₃ films. The semi-transparent yellow C₆₀/PCBM/MAPbBr₃/PEDOT:PSS/ITO glass-structure solar cells exhibit the best performance with a power conversion efficiency of 4.19%. The solar cells are revealed to be suitable for application in building integrated photovoltaic (BIPV) systems. Full article

(This article belongs to the Special Issue Thin Film Semiconductors for Photovoltaic Applications)

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42799 KiB

Open AccessArticle

Machining Duplex Stainless Steel: Comparative Study Regarding End Mill Coated Tools

by Ronny M. Gouveia, F. J. G. Silva, Pedro Reis and A. P. M. Baptista

Coatings 2016, 6(4), 51; https://doi.org/10.3390/coatings6040051 - 26 Oct 2016

Cited by 44 | Viewed by 9753

Abstract

The difficulties in the machining of duplex stainless steel are well known. However, research on this matter is rather limited. Suppliers offer quite different cutting tools for the same raw material, with end mills of two, three or even four knives and a [...] Read more.

The difficulties in the machining of duplex stainless steel are well known. However, research on this matter is rather limited. Suppliers offer quite different cutting tools for the same raw material, with end mills of two, three or even four knives and a huge number of distinct coatings, some of them under commercial brands, making it difficult to assess the advantages they offer. Furthermore, there is a remarkable difference among the several types of duplex stainless steel available nowadays on the market. The present work intends to assess the machining performance of different tools, analyzing the behavior and wear mechanisms with two different cutting lengths, keeping constant the machining trajectory. Some other parameters were also kept constant, such as cutting speed, depth of cut and cutting width, as well as feed per tooth. The machining process was carried out under lubricated conditions, using an emulsion of 5% oil in water. Tools provided with a different number of teeth and surface coatings were tested, analyzing the wear behavior of each cutting length using scanning electron microscopy, trying to identify wear performance and how each coating contributes to increased tool life. The surfaces produced were also analyzed by means of profilometry measurements, correlating tool wear and part surface roughness. This comparative study allows determining the advantages of different tools relative to others, based on coatings and tool geometry. Full article

(This article belongs to the Special Issue Coatings for Cutting Tools)

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4660 KiB

Open AccessArticle

Synthesis of Covalently Cross-Linked Colloidosomes from Peroxidized Pickering Emulsions

by Nadiya Popadyuk, Andriy Popadyuk, Ihor Tarnavchyk, Olha Budishevska, Ananiy Kohut, Andriy Voronov and Stanislav Voronov

Coatings 2016, 6(4), 52; https://doi.org/10.3390/coatings6040052 - 25 Oct 2016

Cited by 5 | Viewed by 6676

Abstract

A new approach to the formation of cross-linked colloidosomes was developed on the basis of Pickering emulsions that were stabilized exclusively by peroxidized colloidal particles. Free radical polymerization and a soft template technique were used to convert droplets of a Pickering emulsion into [...] Read more.

A new approach to the formation of cross-linked colloidosomes was developed on the basis of Pickering emulsions that were stabilized exclusively by peroxidized colloidal particles. Free radical polymerization and a soft template technique were used to convert droplets of a Pickering emulsion into colloidosomes. The peroxidized latex particles were synthesized in the emulsion polymerization process using amphiphilic polyperoxide copolymers poly(2-tert-butylperoxy-2-methyl-5-hexen-3-ine-co-maleic acid) (PM-1-MAc) or poly[N-(tert-butylperoxymethyl)acrylamide]-co-maleic acid (PM-2-MAc), which were applied as both initiators and surfactants (inisurfs). The polymerization in the presence of the inisurfs results in latexes with a controllable amount of peroxide and carboxyl groups at the particle surface. Peroxidized polystyrene latex particles with a covalently grafted layer of inisurf PM-1-MAc or PM-2-MAc were used as Pickering stabilizers to form Pickering emulsions. A mixture of styrene and/or butyl acrylate with divinylbenzene and hexadecane was applied as a template for the synthesis of colloidosomes. Peroxidized latex particles located at the interface are involved in the radical reactions of colloidosomes formation. As a result, covalently cross-linked colloidosomes were obtained. It was demonstrated that the structure of the synthesized (using peroxidized latex particles) colloidosomes depends on the amount of functional groups and pH during the synthesis. Therefore, the size and morphology of colloidosomes can be controlled by latex particle surface properties. Full article

(This article belongs to the Special Issue Polymer Thin Films)

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4841 KiB

Open AccessArticle

The Effect of Sintering Oxygen Partial Pressure on a SmBiO₃ Buffer Layer for Coated Conductors via Chemical Solution Deposition

by Xiaolei Zhu, Yong Zhao, Minghua Pu, Yong Zhang, Hong Zhang and Cuihua Cheng

Coatings 2016, 6(4), 50; https://doi.org/10.3390/coatings6040050 - 21 Oct 2016

Cited by 1 | Viewed by 4385

Abstract

The application of high-temperature YBa₂Cu₃O_7−δ (YBCO) superconducting material is a considerable prospect for the growing energy shortages. Here, SmBiO₃ (SBO) films were deposited on (100)-orientated yttrium-stabilized zirconia (YSZ) simple crystal substrates via the chemical solution deposition (CSD) [...] Read more.

The application of high-temperature YBa₂Cu₃O_7−δ (YBCO) superconducting material is a considerable prospect for the growing energy shortages. Here, SmBiO₃ (SBO) films were deposited on (100)-orientated yttrium-stabilized zirconia (YSZ) simple crystal substrates via the chemical solution deposition (CSD) approach for coated conductors, and the effects of sintering oxygen partial pressure on SBO films were studied. The crystalline structures and surface morphologies of SBO films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscope (AFM). The optimized growth temperature, the intensity ratios of the SBO (200) peak to the SBO (111) peak, and the crystallinities of SBO films increased with the sintering oxygen partial pressure. The SEM and AFM images displayed a smooth and well-distributed surface in the argon atmosphere. The subsequent YBCO films with superconducting transition temperatures (T_c = 89.5 K, 90.2 K, and 86.2 K) and critical current densities (J_c = 0.88 MA/cm², 1.69 MA/cm², and 0.09 MA/cm²; 77 K, self-field) were deposited to further check the qualities of the SBO layer. These results indicated that sintering oxygen partial pressure had an effect on the epitaxial growth of the SBO buffer layer and YBCO superconducting properties. The experimental results may be a usable reference for the epitaxial growth of YBCO-coated conductors and other oxides. Full article

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6364 KiB

Open AccessArticle

Atmospheric Plasma Spraying of Single Phase Lanthanum Zirconate Thermal Barrier Coatings with Optimized Porosity

by Georg Mauer, Linnan Du and Robert Vaßen

Coatings 2016, 6(4), 49; https://doi.org/10.3390/coatings6040049 - 18 Oct 2016

Cited by 25 | Viewed by 6515

Abstract

The shortcomings at elevated operation temperatures of the standard material yttria-stabilized zirconia (YSZ) for thermal barrier coatings (TBCs) have initiated many research activities seeking alternatives. One candidate is the pyrochlore lanthanum zirconate La₂Zr₂O₇ (LZ), which is phase-stable to [...] Read more.

The shortcomings at elevated operation temperatures of the standard material yttria-stabilized zirconia (YSZ) for thermal barrier coatings (TBCs) have initiated many research activities seeking alternatives. One candidate is the pyrochlore lanthanum zirconate La₂Zr₂O₇ (LZ), which is phase-stable to its melting point. At the same time, it shows a lower thermal conductivity and a lower sintering tendency when compared to YSZ. Because of its low thermal expansion coefficient and poor toughness, it is applied in combination with YSZ in double layer TBC systems. It is the current state of knowledge that LZ is prone to lanthanum depletion if processed by plasma spraying. The process conditions have to be selected carefully to avoid this. Furthermore, the amount and morphology of the coating porosity is essential for a good thermo-mechanical performance. In this work, the development and testing of LZ/YSZ double layer TBC systems is described. Initially, suitable basic parameters (torch, plasma gas composition, and power) were tested with respect to coating stoichiometry. Then, microstructures were optimized by adjusting feed rate, spray distance, and by selecting a more appropriate feedstock. Powder particles and coatings were characterized by digital image analysis. Full article

(This article belongs to the Special Issue Five Years of Coatings: Coatings Science and Technology for the 21st Century)

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4977 KiB

Open AccessArticle

Self-Cleaning Mineral Paint for Application in Architectural Heritage

by Sudipto Pal, Vincenzo Contaldi, Antonio Licciulli and Fabio Marzo

Coatings 2016, 6(4), 48; https://doi.org/10.3390/coatings6040048 - 18 Oct 2016

Cited by 27 | Viewed by 9283

Abstract

A mineral silicate paint has been developed for architectural heritage. To enhance durability, any type of organic additive has been avoided. Potassium silicate was the binder agent intended to give strong adherence and durability to stone and concretes. Incorporation of mainly anatase titanium [...] Read more.

A mineral silicate paint has been developed for architectural heritage. To enhance durability, any type of organic additive has been avoided. Potassium silicate was the binder agent intended to give strong adherence and durability to stone and concretes. Incorporation of mainly anatase titanium dioxide was intended to act both as a white, bright pigment and as a photocatalyst. Reflectivity analyses on the paint in the visible-to-near infrared wavelength region show high solar heat reflection. The self-cleaning activity of the mineral paint was evaluated by the degradation of organic dyes under solar light irradiation. Anatase titania was effective in decomposing organic and airborne pollutants with the solar radiation. The optical properties and self-cleaning activity were compared with the organic binder-based paints and commercial paints. Developed paints possess high stability: since they contain only inorganic components that do not fade with exposure to solar radiation, photocatalytic self-cleaning capability further enhances such stability. Full article

(This article belongs to the Special Issue Self-Cleaning, Biocide and Depolluting Coatings for Architectural and Archaeological Heritage)

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1400 KiB

Open AccessReview

Low Energy Atomic Photodesorption from Organic Coatings

by Alessandro Lucchesini, Silvia Gozzini, Carmela Marinelli and Luca Marmugi

Coatings 2016, 6(4), 47; https://doi.org/10.3390/coatings6040047 - 17 Oct 2016

Cited by 8 | Viewed by 5910

Abstract

Organic coatings have been widely used in atomic physics during the last 50 years because of their mechanical properties, allowing preservation of atomic spins after collisions. Nevertheless, this did not produce detailed insight into the characteristics of the coatings and their dynamical interaction [...] Read more.

Organic coatings have been widely used in atomic physics during the last 50 years because of their mechanical properties, allowing preservation of atomic spins after collisions. Nevertheless, this did not produce detailed insight into the characteristics of the coatings and their dynamical interaction with atomic vapors. This has changed since the 1990s, when their adsorption and desorption properties triggered a renewed interest in organic coatings. In particular, a novel class of phenomena produced by non-destructive light-induced desorption of atoms embedded in the coating surface was observed and later applied in different fields. Nowadays, low energy non-resonant atomic photodesorption from organic coatings can be considered an almost standard technique whenever large densities of atomic vapors or fast modulation of their concentration are required. In this paper, we review the steps that led to this widespread diffusion, from the preliminary observations to some of the most recent applications in fundamental and applied physics. Full article

(This article belongs to the Special Issue Advances in Coatings Characterization)

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5708 KiB

Open AccessArticle

Effect of Surface Pretreatment on Quality and Electrochemical Corrosion Properties of Manganese Phosphate on S355J2 HSLA Steel

by Filip Pastorek, Kamil Borko, Stanislava Fintová, Daniel Kajánek and Branislav Hadzima

Coatings 2016, 6(4), 46; https://doi.org/10.3390/coatings6040046 - 15 Oct 2016

Cited by 17 | Viewed by 6891

Abstract

High strength low alloy (HSLA) steels exhibit many outstanding properties for industrial applications but suffer from unsatisfactory corrosion resistance in the presence of aggressive chlorides. Phosphate coatings are widely used on the surface of steels to improve their corrosion properties. This paper evaluates [...] Read more.

High strength low alloy (HSLA) steels exhibit many outstanding properties for industrial applications but suffer from unsatisfactory corrosion resistance in the presence of aggressive chlorides. Phosphate coatings are widely used on the surface of steels to improve their corrosion properties. This paper evaluates the effect of a manganese phosphate coating prepared after various mechanical surface treatments on the electrochemical corrosion characteristics of S355J2 steel in 0.1 M NaCl electrolyte simulating aggressive sea atmosphere. The manganese phosphate coating was created in a solution containing H₃PO₄, MnO₂, dissolved low carbon steel wool, and demineralised H₂O. Scanning electron microscopy (SEM) was used for surface morphology observation supported by energy-dispersive X-ray analysis (EDX). The electrochemical corrosion characteristics were assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PD) measurements in the solution of 0.1 M NaCl. Method of equivalent circuits and Tafel-extrapolation were used for the analysis of the obtained results. Performed experiments and analysis showed that the morphological and corrosion properties of the surface with manganese phosphate are negatively influenced by sandblasting surface pretreatment. Full article

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3248 KiB

Open AccessArticle

Assessing the Protective Quality of Wax Coatings on Bronze Sculptures Using Hydrogel Patches in Impedance Measurements

by Alice H. England, Kathryn N. Hosbein, Capri A. Price, Morgan K. Wylder, Kenna S. Miller and Tami Lasseter Clare

Coatings 2016, 6(4), 45; https://doi.org/10.3390/coatings6040045 - 13 Oct 2016

Cited by 7 | Viewed by 5444

Abstract

In this work, we used chemically cross-linked acrylamide-based hydrogel patches that have been specifically developed for use as solid electrolytes in Electrochemical Impedance Spectroscopy to measure the impedance of two waxed bronze sculptures at the Seattle Art Museum’s (SAM) Olympic Sculpture Park (OSP) [...] Read more.

In this work, we used chemically cross-linked acrylamide-based hydrogel patches that have been specifically developed for use as solid electrolytes in Electrochemical Impedance Spectroscopy to measure the impedance of two waxed bronze sculptures at the Seattle Art Museum’s (SAM) Olympic Sculpture Park (OSP) and compare those results to laboratory test panels. We determined that the impedance response in the frequency range in which measurements may be taken (10 kHz to 1 MHz) is mostly capacitive and that a freshly applied wax coating should ideally be less than 1 nF·cm⁻² for optimal protective performance. Full article

(This article belongs to the Special Issue Advances in Coatings Characterization)

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3911 KiB

Open AccessCommunication

Atmospheric-Pressure Plasma Jet Processed Pt-Decorated Reduced Graphene Oxides for Counter-Electrodes of Dye-Sensitized Solar Cells

by Ting-Hao Wan, Yi-Fan Chiu, Chieh-Wen Chen, Cheng-Che Hsu, I-Chun Cheng and Jian-Zhang Chen

Coatings 2016, 6(4), 44; https://doi.org/10.3390/coatings6040044 - 13 Oct 2016

Cited by 24 | Viewed by 6360

Abstract

Ultrafast atmospheric-pressure plasma jet (APPJ) processed Pt-decorated reduced graphene oxides (rGOs) were used as counter-electrodes in dye-sensitized solar cells (DSSCs). Pastes containing rGO, ethyl cellulose, terpineol, and chloroplatinic acid were screen-printed and sintered by nitrogen dc-pulse APPJs. Pt nanodots were uniformly distributed on [...] Read more.

Ultrafast atmospheric-pressure plasma jet (APPJ) processed Pt-decorated reduced graphene oxides (rGOs) were used as counter-electrodes in dye-sensitized solar cells (DSSCs). Pastes containing rGO, ethyl cellulose, terpineol, and chloroplatinic acid were screen-printed and sintered by nitrogen dc-pulse APPJs. Pt nanodots were uniformly distributed on the rGO flakes. When using Pt-decorated rGOs as the counter electrodes of DSSCs, the efficiency of the DSSC first increased and then decreased as the APPJ processing time increased. Nitrogen APPJs can effectively remove organic binders and can reduce chloroplatinic acid to Pt, thereby improving the efficiency of DSSCs. However, over-calcination by APPJ can damage the graphenes and degrade the DSSCs. The addition of Pt mainly improves the fill factor, which thereby increases the efficiency of DSSCs. The optimized APPJ processing time was merely 9 s owing to the vigorous interaction among the rGOs, chloroplatinic acid and nitrogen APPJs. Full article

(This article belongs to the Special Issue Five Years of Coatings: Coatings Science and Technology for the 21st Century)

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3722 KiB

Open AccessArticle

Translation Effects in Fluorine Doped Tin Oxide Thin Film Properties by Atmospheric Pressure Chemical Vapour Deposition

by Mohammad Afzaal, Heather M. Yates and John L. Hodgkinson

Coatings 2016, 6(4), 43; https://doi.org/10.3390/coatings6040043 - 12 Oct 2016

Cited by 7 | Viewed by 5420

Abstract

In this work, the impact of translation rates in fluorine doped tin oxide (FTO) thin films using atmospheric pressure chemical vapour deposition (APCVD) were studied. We demonstrated that by adjusting the translation speeds of the susceptor, the growth rates of the FTO films [...] Read more.

In this work, the impact of translation rates in fluorine doped tin oxide (FTO) thin films using atmospheric pressure chemical vapour deposition (APCVD) were studied. We demonstrated that by adjusting the translation speeds of the susceptor, the growth rates of the FTO films varied and hence many of the film properties were modified. X-ray powder diffraction showed an increased preferred orientation along the (200) plane at higher translation rates, although with no actual change in the particle sizes. A reduction in dopant level resulted in decreased particle sizes and a much greater degree of (200) preferred orientation. For low dopant concentration levels, atomic force microscope (AFM) studies showed a reduction in roughness (and lower optical haze) with increased translation rate and decreased growth rates. Electrical measurements concluded that the resistivity, carrier concentration, and mobility of films were dependent on the level of fluorine dopant, the translation rate and hence the growth rates of the deposited films. Full article

(This article belongs to the Special Issue Chemical Vapor Deposition)

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605 KiB

Open AccessReview

Molecularly Imprinted Polymer/Metal Organic Framework Based Chemical Sensors

by Zhenzhong Guo, Anca Florea, Mengjuan Jiang, Yong Mei, Weiying Zhang, Aidong Zhang, Robert Săndulescu and Nicole Jaffrezic-Renault

Coatings 2016, 6(4), 42; https://doi.org/10.3390/coatings6040042 - 05 Oct 2016

Cited by 35 | Viewed by 10144

Abstract

The present review describes recent advances in the concept of molecular imprinting using metal organic frameworks (MOF) for development of chemical sensors. Two main strategies regarding the fabrication, performance and applications of recent sensors based on molecularly imprinted polymers associated with MOF are [...] Read more.

The present review describes recent advances in the concept of molecular imprinting using metal organic frameworks (MOF) for development of chemical sensors. Two main strategies regarding the fabrication, performance and applications of recent sensors based on molecularly imprinted polymers associated with MOF are presented: molecularly imprinted MOF films and molecularly imprinted core-shell nanoparticles using MOF as core. The associated transduction modes are also discussed. A brief conclusion and future expectations are described herein. Full article

(This article belongs to the Special Issue Multifunctional Organic-Inorganic Hybrid Thin Films and Coatings)

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Coatings, Volume 6, Issue 4 (December 2016) – 31 articles

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