Hybrid Nanocoatings Research Articles

New PMMA-InP/ZnS nanohybrid coatings for improving the performance of c-Si photovoltaic cells

Abstract Luminescent down-shifting (LDS) nanohybrid films are considered a potential solution to match the absorption spectrum of photovoltaic (PV) cells with the AM1.5 solar spectrum. LDS films were prepared by spin-coating polymethyl methacrylate (PMMA) doped with indium phosphide/zinc sulfide (InP/ZnS) quantum dots (QDs). The effect of doping concentration was investigated using X-ray diffraction, thermogravimetric analysis, transmission, and fluorescence spectroscopy. The results demonstrated that all PMMA LDS nanohybrid films were amorphous and exhibited thermal and chemical stability for all the doping concentrations of QDs. The optimal doping concentration was 0.06 wt%, demonstrating a tunable emission of the highest fluorescence quantum yield of 92% and the lowest reabsorption effect. This film showed the maximum enhancement of the efficiency of c-Si PV cells by 24.28% due to the down-conversion of ultraviolet A (UVA) portion of solar spectrum (320–400 nm) to match the sensitivity of c-Si PV cells. The implications of these results are significant for advancing affordable and clean energy in alignment with important sustainable development goals.

Poly(Allylamine Hydrochloride) and ZnO Nanohybrid Coating for the Development of Hydrophobic, Antibacterial, and Biocompatible Textiles.

In healthcare facilities, infections caused by Staphylococcus aureus (S. aureus) from textile materials are a cause for concern, and nanomaterials are one of the solutions; however, their impact on safety and biocompatibility with the human body must not be neglected. This study aimed to develop a novel multilayer coating with poly(allylamine hydrochloride) (PAH) and immobilized ZnO nanoparticles (ZnO NPs) to make efficient antibacterial and biocompatible cotton, polyester, and nylon textiles. For this purpose, the coated textiles were characterized with profilometry, contact angles, and electrokinetic analyzer measurements. The ZnO NPs on the textiles were analyzed by scanning electron microscopy and inductively coupled plasma mass spectrometry. The antibacterial tests were conducted with S. aureus and biocompatibility with immortalized human keratinocyte cells. The results demonstrated successful PAH/ZnO coating formation on the textiles, demonstrating weak hydrophobic properties. Furthermore, PAH multilayers caused complete ZnO NP immobilization on the coated textiles. All coated textiles showed strong growth inhibition (2-3-log reduction) in planktonic and adhered S. aureus cells. The bacterial viability was reduced by more than 99%. Cotton, due to its better ZnO NP adherence, demonstrated a slightly higher antibacterial performance than polyester and nylon. The coating procedure enables the binding of ZnO NPs in an amount (<30 µg cm-2) that, after complete dissolution, is significantly below the concentration causing cytotoxicity (10 µg mL-1).

Preparation of transparent hard GPTMS-Al2O3 thin films on a polycarbonate substrate

Using polycarbonate (PC) due to its incredible properties as a suitable replacement for inorganic glasses has been increasing. Nevertheless, the low hardness limits its applications in more industries. Hence, it requires to be coated with hard anti-scratch optical coatings to overcome these limitations. In the current work, sol-gel-prepared thin films based on (3-Glycidyloxypropyl) trimethoxysilane (GPTMS)-Al2O3 were applied on PC substrates. First, silica and alumina sols were synthesized by a sol-gel process, individually. Then, the prepared sols were mixed at different ratios and dip-coated on the plasma etched pretreatment PC substrates. Curing of the samples was done in an oven at 100 °C. The produced thin films were characterized by field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Attenuated total reflectance -Fourier transform infrared spectroscopy (ATR-FTIR), and UV/Vis spectroscopy techniques. The obtained results indicated that the PC hardness increased from 6B to H by deposition of nano-hybrid coatings. After applying a nano-hybrid coating, transmittance was increased from 88 % to 91 % and the reflectance decreased from 10 % to 5 %. Sample with a 1:4 GPTMS-Al2O3 ratio showed the best results.

Development and testing of environment friendly nanohybrid coatings for sustainable agriculture technologies

Less than 50% of the applied urea fertilizer is taken up by plants due to poor nitrogen (N) use efficiency which affects overall agricultural productivity and leads to serious environmental and economic problems. Additionally, soils with high salinity might limit zinc (Zn) availability. Low Zn use efficiency (<30%) when applied as synthetic salts, e.g., zinc sulfate has therefore minimized their applicability. Within the past two decades, nanotechnology has gained a lot of interest in the development of effective nano fertilizers with high nutrient use efficiency (NUE). In this perspective, the approach of coating conventional fertilizers with nano materials especially, the ones which are essential nutrients has researched because of their high use efficiency and reduced losses. In this work, a novel and innovative formulation of hybrid nano fertilizer has been prepared for the sustainable release of nutrients. Zinc oxide nanoparticles (ZnO-NPs <50 nm) were incorporated into the biodegradable polymer (gelatin) and coated on urea using a fluidized bed coater. Among all the formulations, GZnSNPs (1.5% gelatin+0.5% elemental Zn as ZnO-NPs) showed a significant delay in urea release (<80 %) after 120 min). The sand column experiment showed sustainable Zn release for GZnSNPs i.e., 2.7 ppm vs. 3.5 ppm (GZnS) after the 6th day. Moreover, a substantial increase in wheat grain yield (6500 kg/ha), N uptake (46.5 kg/ha) and Zn uptake (21.64 g/ha) were observed for fields amended with GZnSNPs. The composition of GZnSNPs was valuable since this attracted the highest return relative to the other treatments. Gelatin supplied small N-containing molecules, resulting in extra value addition with ZnO-NPs thus increasing yield and fertilizer properties more relative to the same amount of elemental Zn given via bulk salt. Therefore, the findings of the current study recommend the use of ZnO-NPs in the agricultural sector without any negative effects on yield and NUE.

Development and characterization of DGEBA-APTES-ZrO2 nanocomposite coatings for anti-corrosion and anti-fouling

Tetraethylenetetramine (TETA), 3-aminopropylethoxysilane-treated ZrO2 nanoparticles, and diglycidyl ethers of bisphenol-A (DGEBA) were used to create an epoxy nanocomposite (DGEBA-APTES-ZrO2). The newly synthesized APTES-ZrO2 was evaluated using FTIR, XRD, SEM, AFM, TEM and elemental analysis for structural and compositional analysis. Due to its resilience in acidic, basic and saline conditions, mild steel is crucial in sectors like shipbuilding and the automobile industry. ZrO2 nanoparticles have excellent corrosion resistance. As a result, it is intended to prepare DGEBA-APTES-ZrO2 for a barrier layer that prevents corrosion on mild steel surfaces. FTIR spectroscopy tests provided proof of DGEBA-APTES-ZrO2-coated mild steel’s ability to limit corrosion and microbiological growth. Using salt spray and an electrochemical impedance technique, corrosion inhibition was evaluated. On mild steel surfaces, DGEBA-APTES-ZrO2 nanohybrid coatings demonstrated excellent corrosion prevention and antifouling.

Tungsten-based hybrid nanocomposite thin film coated fabric for gamma, neutron, and X-ray attenuation

Ionizing radiation such as x-ray, γ-ray and neutron ray have serious negative health effects on human being. Hence, new and smart textile fabric nanocoating was facilely developed and coated on lab coat cloth. The newly hybrid nanocoatings were fabricated from uniform dispersion of PbWO4 NPs and Bi2WO6 NPs of an average sizes of 47.38 ± 7.6 and 9.1 ± 1.8 nm, respectively in chitosan solution. The dispersion of tungsten-based nanoparticles was performed using ultrasonication process, then well dispersed hybrid nanocoatings were coated on textile fabrics derived lab coat. The mass ratio of nanoparticles in nanocoatings were altered and optimized. The attenuation properties of x-ray/gamma ray and neutron ray were studied and achieving good shielding properties compared to uncoated fabrics. Additionally, the antibacterial and mechanical properties of coated fabrics were evaluated. The coated textile fabrics achieved clear inhibition zone of 4 mm compared to zero clear inhibition zone for uncoated ones against E-Coli. Moreover, the developed coating layer achieved good reinforcement effect recording superior tensile strength by 11.5% than uncoated sample. The dispersion properties of nanoparticles in coating nanocomposites were investigated using microscopic tools.

Green Fabrication of Anticorrosive, Antibacterial, and SERS Active Nanohybrid Coatings by Dual-Spinneret Electrospinning

The development of sustainable and nontoxic corrosion coatings in abiotic and biotic environments has recently attracted significant attention. Herein, we developed nanohybrid coatings containing polysulfone (PSU), cyclodextrin (CD), zeolite (10 μm size), and biogenic silver nanoparticles (AgNPs, 40 nm diameter) via direct one-step dual-spinneret electrospinning. In the fabricated nanohybrid coatings, zeolites were used as a nontoxic anticorrosive inhibitor, and biogenic AgNPs serve as antibacterial agents due to their environmentally friendly and low-cost characteristics. Scanning electron microscopy and transmission electron microscopy analyses indicated that the zeolite and AgNP-embedded nanofibers have homogeneous and bead-free morphologies. Moreover, the elemental distribution mapping of the fabricated platforms demonstrated a well-distributed mixture of PSU/zeolite and CD/AgNPs in the nanofiber mats which were fabricated via such a dual-spinneret technique. The surface-enhanced Raman scattering activities of the fabricated nanofiber mats were also evaluated using methylene blue, rhodamine 6 G, crystal violet, and malachite green as probe molecules. Additionally, the antibacterial response of the fabricated nanohybrid coatings against four pathogenic bacteria (Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 23213, Pseudomonas aeruginosa ATCC 27853, and Klebsiella pneumoniae ATCC 700603) was investigated, which indicated the critical role of zeolite/AgNPs in suppressing the bacterial growth. Tafel measurements also showed that the PSU/zeolite/HPβCD/AgNPs hybrid coating reduced the corrosion current density of the Cu surface in the presence of P. aeruginosa ATCC 27853, which is a biofilm-producing bacteria, compared to the uncoated surface. The antimicrobial and corrosion inhibition ability of the fabricated nanohybrid coatings offers promising opportunities for the microbiologically influenced corrosion inhibition applications.

Modifying flexible polymer films towards superhydrophobicity and superoleophobicity by utilizing water-based nanohybrid coatings.

The development of superhydrophobic and/or superoleophobic materials has been attracting the attention of the scientific community due to their wide range of applications. In this work, waterborne nanocomposite coatings were developed to be deposited onto flexible polyethylene films in order to modify them into superhydrophobic and even superoleophobic. The coatings consisted of either a low surface energy mixture of silanes/siloxanes or a fluoropolymer in conjunction with the appropriate inorganic nanoparticles that provide the necessary roughness; the effects of nanoparticle type and content on the behaviour was investigated. In both cases, the surface properties were investigated, and the polymer films were found to be superhydrophobic. Depending on the system utilized, the final material exhibited either low water adhesion, thus, being water repellent, or high water adhesion. The use of the fluoropolymer has led to coatings that exhibited superoleophobic behaviour for various organic compounds, as well. The application of the coatings did not influence either the optical transparency or the thermal properties of the polyethylene films. Moreover, the coated surfaces show similar or even better mechanical properties, scratch resistance and chemical durability in comparison to the neat LDPE film.

Functionalized Ti3C2Tx-based nanocomposite coatings for anticorrosion and antifouling applications

Marine corrosion and biofouling are a major issue affecting the development of the marine industry. Traditional single-function coatings, such as those that provide either antifouling or anticorrosion, cannot meet the requirements in the current hostile conditions. In our study, block copolymer-functionalized Ti3C2Tx was successful prepared and employed to synthesize a nanocomposite coating with satisfactory antifouling and anticorrosion performances, in which the anticorrosion agent poly(2-mercaptobenzothiazole) (PMBTMA) was first grafted on the Ti3C2Tx surface, after which the antifouling agent poly(3-sulfopropyl methacrylate potassium (PSPMA) was grafted via surface-initiated atom transfer radical polymerization (SI-ATRP), to obtain the block copolymer (PMBTMA-co-PSPMA)-functionalized Ti3C2Tx (abbreviated as TMS). An appropriate corrosion protection and antifouling mechanism in the functionalized Ti3C2Tx-based epoxy nanohybrid coatings is proposed. It is noteworthy that the antibacterial activity of the proposed coating stems from the synergistic bactericidal effect of Ti3C2Tx and 2-mercaptobenzothiazole (MBT). The outstanding antibacterial properties of the TMS and the strong surface hydration of the anionic polymer brushes PSPMA, endow the as-prepared TMS-based nanocomposite coating (TMS/EP) with good antifouling performance (removal of more than 55% of bacteria and removal rate of microalgae up to 71%). More importantly, the TMS/EP has excellent corrosion resistance ability, which is due to the good synergistic anticorrosion barrier effect of Ti3C2Tx nanosheets and the on-demand release of corrosion inhibitor MBT during the corrosion process.

Pyrroloquinoline Based Styryl Dyes Doped PMMA, PS, and PS/TiO2 Polymer for Fluorescent Applications.

This article presents two highly fluorescent donor-π-acceptor (D-π-A) moieties containing an electron-donating carbazole and phenothiazine donors fused with electron-withdrawing pyrrolo-quinoline acceptor dyes, PQC and PQPT. We also discussed the polymerization and film-forming process of dye PQC and PQPT doped in poly (methyl methacrylate) (PMMA) and polystyrene (PS) polymer to find their optical applications in polymer-based technology. We investigated the fluorescent properties of dyes PQC and PQPT from 0.01 to 1 wt% in poly(methyl methacrylate) (PMMA). We also investigated the changes in the spectrum shape and shift in wavelength with changes in poly(methyl methacrylate) (PMMA), polystyrene (PS), and TiO2 doped in polystyrene (PS/TiO2). The analysis of surface morphology of prepared polymer samples was done with the help of a scanning electron microscope. The thermal and photostability of synthesized dyes in poly (methyl methacrylate) (PMMA), polystyrene (PS), and TiO2 doped in polystyrene (PS/TiO2) were investigated to get detailed information owing to the application of fluorescent polymers in the field of optoelectronic, nanohybrid coatings in solar concentrators, etc.Graphical

Multifunctional ZnO-Co3O4 @ polymer hybrid nanocoatings with controlled adsorption, photocatalytic and anti-microbial functions for polluted water systems.

Triple action pollutant responsive multi-layer hybrid nanocoatings of architecture PEI(PAA/ZnO-Co3O4)n were constructed through ZnO-Co3O4 binary oxide co-precipitation followed by its inclusion in multi-layer polymeric thin films using Layer-by-Layer (LbL) deposition. Characterization of the designed architecture was carried out via FTIR, XRD, UV-Vis, and Raman spectroscopic studies to evaluate the chemical nature, bonding, and crystallographic behavior of ZnO-Co3O4. Peaks of ZnO-Co3O4 were recorded at 586.38, 486.08, and 443.64cm-1 while pronounced shifting of ZnO characteristic E2 (high) peak ~ 450cm-1 and appearance of modes around 495, 530, 630, and 719cm-1 indexed via Raman studies validated Co3O4 impregnation into ZnO structure. XRD patterns of ZnO-Co3O4 compared to their previously reported pristine structures also justified the formation of binary oxide as unit composite. SEM micrographs confirmed homogenous multi-layered depositions while EDX analysis confirmed their uniform elemental distribution in the unit structure. Sequential multi-layer buildup up to 48 layer pairs was monitored using ellipsometry with maximum film thickness ~ 89nm and by UV-Vis at 376nm. The prepared thin films exhibited significant photodegradation of methylene blue ~ 91% and Cu (II) adsorption capacity ~ 89% within first 90min of contact, along with prominent bactericidal efficiency against E. coli within 24h of reaction time. FAAS, ICP-OES, and UV-Vis spectroscopy analyses make these multifunctional hybrid nanocoatings promising for industrial wastewater as well as drinking water purification setups. Furthermore, protuberant recycling and regenerative capacity make these hybrid nanocoatings an eco-friendly system for hydro-remediation.

Hybrid nanocoatings of self-assembled organic-inorganic amphiphiles for prevention of implant infections

Antimicrobial coatings are one of the most promising strategies to prevent bacterial infections in orthopedic and dental implants. Combining antimicrobial agents with different antimicrobial mechanisms might have synergistic effects and be more potent. Others have shown that nanocomposites of silver nanoparticles (AgNPs) decorated with antimicrobial peptides (AMPs) show increased potency as free agents in solution. However, similar nanocomposites have not been explored to coat biomaterials through cooperative weak electrostatic attraction forces between AMP, AgNPs and substrates in need of protection against infection. In this work, we synthesized self-assembled antimicrobial amphiphiles of an AMP, GL13K. Then, we decorated the AMP nanostructures with AgNPs, which were finally used to coat etched Ti (eTi) surfaces. The strong hydrogen bonding between the AMP amphiphiles and the polar eTi yielded a robust and stable coating. When compared to single AgNP or single AMP coatings, our hybrid nanocoatings had notably higher in vitro antimicrobial potency against multiple bacteria strains related to implant infection. The hybrid coating also showed relevant antimicrobial activity in an in vivo subcutaneous infection model in rats. This work advances the application of AgNP/AMP nanocomposites as effective coatings for prevention of implant infections. Statement of significanceHigh morbidity, mortality and elevated costs are associated with orthopedic and dental implant infections. Conventional antibiotic treatment is ineffective due to barrier-like extracellular polymeric substances in biofilms and the increasing threat from antibiotic resistance. Antimicrobial coatings are one of the most promising strategies, but the performance is usually unsatisfactory, especially when tested in vivo. Here, we present a hybrid nanocoating with different modes of action to prevent implant infections using self-assembled antimicrobial peptide (AMP) amphiphiles decorated with silver nanoparticles (AgNPs). When compared to single AgNP or AMP coatings, our hybrid nanocoatings showed significant increases in antimicrobial potency against multiple implant infection-related bacterial strains in vitro and in an in vivo rat subcutaneous infection model.

Comb-like poly(dodecyl methacrylate) modified SiO2 nanoparticles as nanohybrid coatings: Electron beam grafting and tuning superhydrophobic/water-repellent surface studies

The current research focuses on tailoring silica nanoparticles (SiO2NPs) with comb-like poly(dodecyl methacrylate) (PDMA) brushes and tuning coating parameters based on roller coating process for confining surface morphology towards hydrophobic and superhydrophobic including water-repellent surface. Electron beam (EB) induced a simultaneous “graft-from” polymerization of DMA monomer onto vinyl modified SiO2NPs (SiO2NPs-V) was established in an inventive castor oil/ethanol mixed solvent. Functional surface chemistry of SiO2NPs and nanorough surface topography controlled by NPs content and coating thickness mainly influences the hydrophobic/superhydrophobic, water-repellent, and water absorption properties including gloss values, whiteness and yellowness index of coated papers. The papers coated with SiO2NPs-V-PDMA/PVA of 6–10 wt% with the thickness of ~10–14 μm exhibited matt surface and provided superhydrophobic and water-repellent properties. The coated paper has a desirable and stable water contact angle of 152°, low droplet adhesion with lower dynamic tilting angle (<5°), and 5.3-folds reduced water absorption. Our investigation provides compelling evidence that the SiO2NPs-V-PDMA obtained from EB modification and the developed coating formula for roller-based coating process are realistic approaches for hydrophobic/superhydrophobic coatings and printing inks for paper-based industries.

Tea–Essential Oil–Metal Hybrid Nanocoatings for Bacterial and Viral Inactivation

Natural plant-derived antimicrobial nanocoatings have been synthesized by mixing brewed tea with cinnamaldehyde oil. Concurrent addition of copper or silver salts produces hybrid tea-cinnamaldehyde-copper or tea-cinnamaldehyde-silver nanocoatings, respectively. Tea-cinnamaldehyde, tea-cinnamaldehyde-copper, and tea-cinnamaldehyde-silver coatings are all found to display strong antibacterial efficacy against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus (Log10 Reduction = 8.44 and 7.90, respectively). Tea-cinnamaldehyde-copper and tea-cinnamaldehyde-silver hybrid nanocoatings deposited onto nonwoven polypropylene provide 98.6 and 99.8% deactivation, respectively, toward murine coronavirus MHV-A59 (a potential surrogate for COVID-19 global pandemic coronavirus SARS-CoV-2). Key advantages of this approach are that the coating fabrication involves just a single step, utilizes cheap reagents (which are widely available over the counter to the general public), does not require any equipment apart from a container, and the coatings spontaneously adhere to a variety of substrate materials (including silicon, glass, polyester, nonwoven polypropylene, poly(tetrafluoroethylene), and cotton). Tea is one of the most ubiquitous beverages in the world, meaning that these antimicrobial coatings could be produced locally almost anywhere and by anyone without the need for any specialized technical training or expertize (for example, at remote field hospitals during humanitarian crises and in low-income countries). © 2021 The Authors. Published by American Chemical Society.

Bioinspired Redwood-Like Scaffolds Coordinated by In Situ-Generated Silica-Containing Hybrid Nanocoatings Promote Angiogenesis and Osteogenesis both In Vitro and In Vivo.

Inspired by natural redwood and bone, a biomimetic strategy is presented to develop a highly bioactive redwood-like nanocomposite via radial freeze casting of biocompatible hydrogels followed by the in situ coprecipitation of a Si-containing CaP hybrid nanocoating (SCPN). The engineered material displays radially aligned macrochannels and a porous network structure similar to those of natural redwood. In addition to acting as a mechanical reinforcement, introducing SCPNs into the weak redwood-like scaffold yields not only a nanoroughened surface topography, a low swelling ratio, retarded enzymatic degradation, and enhanced protein absorption abilities but also the sustained sequential release of Si and Ca ions, thereby providing essential biophysical and biochemical cues for effective bone regeneration. Benefiting from the redwood-like structures and bioactive SCPNs, the biomimetic materials create a favorable microenvironment for promoting the initial adhesion, spreading, proliferation, and migration of bone marrow-derived mesenchymal stem cells and human umbilical vein endothelial cells. Furthermore, the in vitro and in vivo data showed that the biocompatible redwood-like scaffold with precipitated SCPN can synergistically promote osteogenesis and angiogenesis in their aligned direction. Collectively, this work presents a novel bioinspired redwood-like material with multifunctional properties that provides new insight into bone defect repair.

Effect on hydrophobicity and antimicrobial behavior of epoxy resin due to silane functionalized TiO2 as nanofillers

4-Aminobutyltriethoxysilane functionalized TiO2 nanoparticles (TiO2-ABTES) dispersed diglycidyl ethers of bisphenol-A (DGEBA-GY260) were studied for antimicrobial applications. Epoxy nano-hybrid coatings of four different concentrations (1, 3, 5 and 7 wt %) were developed using TiO2-ABTES as the dispersed phase and a commercially available DGEBA as the matrix phase. Triethylenetetramine (TETA) used to cure the nanocomposites films. The structural characteristics of these materials were investigated by Fourier transform infrared spectral studies, Scanning electron microscopy and atomic force microscope analysis. The surface characteristics of the samples were estimated from contact angle measurements and calculated surface free energy and adhesion energy. The bacteriological tests were done using the agar diffusion method with different concentrations of TiO2-ABTES. The antimicrobial activity test noted that the antimicrobial activity of 7 wt% TiO2-ABTES nanoparticles loaded epoxy nanocomposite film has a better inhibition zone against all pathogens under study.

Synergistic Flame Retardant Effects of Carbon Nanotube‐Based Multilayer Nanocoatings

AbstractIn an effort to develop highly functionalized flame retardant materials, hybrid nanocoatings are prepared by alternately depositing a positively charged polyaniline (PANi) and negatively charged montmorillonite (MMT) using the layer‐by‐layer (LbL) assembly technique. Carbon nanotubes (CNTs) are employed in polymer nanocomposites as effective reinforcement, where nanotubes are stabilized in MMT aqueous solution. The 3D structure and high density of CNTs deposited in the PANi/CNTs‐MMT multilayers produce thicker and heavier coatings in comparison to the LbL assemblies without CNTs. Vertical and horizontal flame testing show that the incorporation of CNTs improves fire resistance. Additionally, cone calorimetry reveals that stacking two nanomaterials (MMT and CNTs) in a single coating shows a significant reduction in peak heat release rate (up to 51%), total smoke release (up to 47%), and total heat release (up to 37%) for the polyurethane foam. The enhancement of flame retardancy is attributed to a synergistic effect; MMT serves as a physical barrier that retards the diffusion of heat and gas. The addition of CNTs strengthens the thermal stability and high char yield. These results, coupled with the simplicity with which the LbL deposition is applied, present a viable alternative to halogen‐free flame retardant nanocoatings to natural and synthetic fibers.

Electrochemical behavior of Zn‐REP nanohybrid coatings during marine Shewanella sp. biofilm formation

AbstractNanohybrid coatings, particularly zinc‐rich epoxy coatings, can protect steel from the harsh marine environment through a physical barrier mechanism and a cathodic protective effect based on anodic electrochemical reactions involving zinc particles in the coating. New additives, such as carbon nanotubes (CNTs), produce more efficient multifunctional coatings by enhancing both protective mechanisms. In this study, the electrochemical behavior and corrosion mechanisms of zinc‐rich epoxy nanohybrid coatings with the addition of CNTs were investigated in the presence of a Shewanella sp. marine strain to evaluate their influence on biofilm formation by this Gram‐negative bacterium. The electrochemical activity was monitored over time with open‐circuit potential, electrochemical impedance spectroscopy, and scanning electron microscopy coupled with energy‐dispersive X‐ray spectroscopy. A mixed mechanism was observed starting from early exposure. When the content of CNTs was doubled, the biofilm adherence improved, thus suggesting a favorable effect of CNTs on biofilm formation, attributable to increased production of bacterial exopolymeric substances facilitating biofilm development. The electrochemical impedance spectroscopy results suggested a correlation with biofilm formation as a second barrier layer with the lowest impedance magnitude in coatings with different multiwalled CNT content.

Comparative Study on 3D Printed Ti6Al4V Scaffolds with Surface Modifications Using Hydrothermal Treatment and Microarc Oxidation to Enhance Osteogenic Activity.

Titanium (Ti) and its alloys have been widely used in clinics as preferred materials for bone tissue repair and replacement. However, the lack of biological activity of Ti limits its clinical applications. Surface modification of Ti with bioactive elements has always been a research hotspot. In this study, to promote the osseointegration of Ti6Al4V (Ti64) implants, calcium (Ca), oxygen (O), and phosphorus (P) codoped multifunctional micro–nanohybrid coatings were prepared on a three-dimensional (3D) printed porous Ti64 surface by microarc oxidation (MAO) and a hydrothermal method (HT). The surface morphologies, chemical compositions, and surface/cell interactions of the obtained coatings were studied. In vitro experiments indicated that all hybrid coating-modified Ti64 implants could enhance protein adsorption and MC3T3 osteoblasts’ activity, adhesion, and differentiation ability. In vivo experiments showed that the hybrid coating promoted early osseointegration. By comparison, microarc oxidation-treated Ti64 (M-Ti) has the best biological activity and the strongest ability of osseointegration. It provides important theoretical significance and potential application prospects for improving the biological activity of Ti implants.

Smart Coatings for Corrosion Protection: On the Need for New Coating Concepts

Ideally smart coatings for corrosion protection have to be able to protect the underlying metal from corrosion by providing excellent barrier properties, at the same time showing a fast and efficient self-healing in case a defect down to the metal is inflicted into them, while being as delamination resistant as possible.These seem to be basically incompatible properties, as either mobility of species is high or the coating is highly impermeable, i.e. it is difficult to envisage a coating that can be both at the same time. In fact, in recent works we have shown that for excellent self-healing performance especially the resistance against cathodic delamination of a coating should be significantly weakened [1, 2]. Using conductive polymer additions to non-conductive coatings, both high self-healing activity [1-3] as well as high resistance against cathodic delamination [4, 5] can be controlled in a wide range.Based on an in-depth understanding of the underlying mechanisms we are currently working on strategies for developing coatings that show excellent active as well as passive protection properties. Latest progress of the research on this topic well be presented and the implication will be discussed.[1] M. Uebel, L. Exbrayat, M. rabe, T.H. Tran, D. Crespy, M. Rohwerder, On the Role of Trigger Signal Spreading Velocity for Efficient Self-Healing Coatings for Corrosion Protection, Electrochem. Soc. 165 (2018) C1017-C1027[2] H. Tran , A. Vimalanandan , G.Genchev , J. Fickert , K. Landfester, D. Crespy , M.Rohwerder, Regenerative Nano-Hybrid Coating Tailored for Autonomous Corrosion Protection, Advanced Materials 27(25) (2015) 3825-3830[3] A. Vimalanandan, L.P. Lv, T.H. Tran, K. Landfester, D. Crespy, M. Rohwerder, Redox-Responsive Self-Healing for Corrosion Protection, Advanced Materials 25(48) (2013) 6980-6984[4] Anna Merz, Matthias Uebel, Michael Rohwerder, The Protection Zone: A Long-Range Corrosion Protection Mechanism around Conducting Polymer Particles in Composite Coatings: Part I. Polyaniline and Polypyrrole, Electrochem. Soc. 166 (2019) C304-C313[5] Anna Merz, Michael Rohwerder, The Protection Zone: A Long-Range Corrosion Protection Mechanism around Conducting Polymer Particles in Composite Coatings: Part II. PEDOT:PSS, Electrochem. Soc. 166 (2019) C314-C320