Anticorrosive Coatings Research Articles

Enhance of Anticorrosive Properties of Green-PU-Silica Coatings by Incorporation of Lignin

The tailored combination of organic polymers and inorganic ceramics can produce organic-inorganic hybrid (OIH) coatings to act as corrosion protection barriers.1 ,2 In this work, we proposed the use of glycerol and lignin as polyol sources to prepare green polyurethane to be used in the sol-gel synthesis of PU-silica hybrid coating for steel corrosion protection. The PU pre-polymer was synthesized from MDI (4,4’-methylenebis (phenyl isocyanate)), glycerol and lignin, and then it was functionalized with APTES ((3-aminopropyl) triethoxysilane) to ensure the covalent conjugation with polysilanol network formed from TEOS (Tetraethyl orthsilicate) sol-gel reactions leading to a class II hybrid. Three samples were synthesized varying the proportion between the polyols, one sample containing only glycerol (ZL_PU-S) and the others with a molar ratio of GlyOH:LigOH of 7.5 and 16.1 (FL_PU-S and HL_PU-S, respectively).The effects of lignin content on the structure and properties were evaluated. FTIR and 13C NMR showed the formation of the PU-silica hybrid and the total incorporation of lignin to the PU chain. TGA showed that the presence of lignin into the OIH matrix improved the thermal stability allowing to continuous increase of the initial temperature of mass loss: T5% = 173, 186 and 190 °C for ZL_PU-S, HL_PU-S and FL_PU-S, respectively. The steel substrate coated with the OIH show a water contact angle of 90° for the samples HL_PU-S and FL_PU-S and 80° for ZL_PU-S. The electrochemical impedance spectroscopy analysis performed in a three electrode cell configuration with a NaCl 3.5% solution, showed that the coating with the higher lignin concentration, FL_PU-S, have a |Z| of over 1010 Ω.cm2 for the lowest frequency point and a phase angle of approximately -90° during the 28 days of analysis. The FL_PU-S had better performance than the coating without lignin, ZL_PU-S, that presented |Z|=107 Ω.cm2 on the initial period of immersion with a decrease of two decades in value through out the subsequent period of analysis. In summary, the addition of lignin to the PU polymeric matrix enables the production of a green OIH coating with high efficiency for corrosion protection of steel substrates.Acknowledgments: This work was supported by the Brazilian funding agencies CNPq, FAPESP, CAPES and by PROPe UNESP.Keywords: Renewable feedstock, green coating, PU-silica, lignin, corrosion protection, sol-gel process, hydrophobic coating.1-BRAZ, Á. G.; PULCINELLI, S. H.; SANTILLI, C. V. Glycerol-based polyurethane-silica organic-inorganic hybrid as an anticorrosive coating. Progress in Organic Coatings, v. 169, p. 1069392-HARB, S. V. et al. Siloxane–PMMA hybrid anti-corrosion coatings reinforced by lignin. Surface and Coatings Technology, v. 275, p. 9-16.

Anisotropic dispersion promoting and passivation protecting of CA@JNs@Zn2+ Janus nanosheets on epoxy anticorrosive coatings

Defects in the curing process of epoxy coatings tend to deteriorate the anticorrosion performance of the coatings. An important way to enhance the anticorrosion performance of epoxy coatings is to add flaky fillers. In this paper, anisotropic Janus nanosheets (JNs) were prepared and modified by cardanol (CA) and Zn2+. Then, the obtained CA@JNs@Zn2+ Janus composite nanosheets were introduced into epoxy coatings. When the content of CA@JNs@Zn2+ is 0.2 %, the mechanical properties and corrosion resistance of the coating were effectively improved. The tensile strength of 0.2 %-CA@JNs@Zn2+/EP coating is 79 % higher than that of pure epoxy coating. The EIS analysis showed that the low-frequency impedance of the coating remained as high as 16.45 Gohm·cm2 after 35 days of immersion, and remained above 10 Gohm·cm2 during the whole immersion period, which demonstrating the optimal corrosion resistance. This paper provides a theoretical basis for the preliminary application of Janus material in the field of anticorrosion, and the prepared composite coatings are expected to be used for anticorrosion in harsh environment.

Ni/Al2O3 waste catalyst loaded with pomegranate peel extract and Ce3+ ions as a sustainable active/barrier pigment for epoxy anti-corrosion coating

Nickel-containing alumina (Ni/Al2O3) is a commercially available catalyst that is widely used for desulfurizing crude oil components. However, the accumulation of carbon and sulfur on the catalyst surface can lead to its deactivation, making its disposal environmentally hazardous. Additionally, extracting nickel from waste catalysts is not economically feasible. The high specific surface area of Ni/Al2O3 waste catalyst (Cat), which can exceed 100 m2/g, makes it a promising material for repurposing as nanocontainers for anti-corrosive coatings. In this study, an intelligent epoxy (EP) anti-corrosion coating incorporating Cat for encapsulating a green hybrid corrosion inhibitor based on pomegranate peel extract (PPE) and Ce3+ ions was developed. Brunauer-Emmett-Teller (BET) analysis revealed that Cat nanopigment possessed a mesoporous structure and a surface area of 127 m2/g, rendering it a suitable candidate for encapsulating corrosion inhibitors. Fourier-transform infrared spectroscopy (FTIR), BET, and thermogravimetric analysis (TGA) were employed to confirm inhibitor loading in the Cat nanopigment. The self-healing and protective properties of the prepared EP-based composite coatings were evaluated using salt spray and electrochemical impedance spectroscopy (EIS) tests. The findings demonstrated a 440% improvement in the overall corrosion resistance (RT) of Ce-PPE@Cat/EP coating compared to blank/EP coatings.

Physical and chemical chloride binding characteristics of the hydration products for phosphoaluminate cement

Phosphoaluminate cement (PAC) has the potential to prepare the anti-corrosive coatings for rebar due to with high compactness and resistance to chloride. Whereas, the reports of the binding type, its ratio and binding capacity of PAC for chloride ions are not found up to now. Thus, the chloride binding performance of PAC hydration products, as well as the binding isotherms and kinetic models, were investigated in this work. The experimental results showed that the binding capacity of the fully hydrated sample reached 21.03 mg/g in 0.56 mol/L NaCl solution. Up to 80 % of this total was non-water-soluble chloride, dominated by the chemical binding of calcium hydroaluminates (i.e., C(A,P)H10 and C2(A,P)H8). The water-soluble chloride at 20 ℃ accounted for only 20 % and was mainly adsorbed physically by Al(OH)3 and Fe(OH)3 gels. The whole chloride binding process of hydration products was well described using Freundlich isotherm and Elovich kinetic models. Its non-water-soluble bound chloride was more suitable for D-R isotherm and Elovich kinetic models, while the water-soluble bound chloride was more applicable to Freundlich isotherm and PSO kinetic models. These data will offer theoretical support for the rational use of PAC in constructions exposed to high chloride environments, such as the ocean.

A High-Performance Anti-Corrosive Epoxy Coating Based on Ultra-Thin Hydroxyapatite Nanosheets with pH-Responsive Functions.

The changes in the working environment have necessitated greater requirements in terms of the long-term anti-corrosion ability of metal anti-corrosion coatings, and the emergence of intelligent coatings has met this demand. A nanocontainer with a hydrophobic inner cavity and hydrophilic outer cavity called β-cyclodextrin (β-CD) was grafted onto the surface of hydroxyapatite (HAp) with a silane coupling agent, encapsulating benzotriazole (BTA) and embedded in epoxy resin to improve the coating anticorrosion performance. The excellent corrosion resistance of the coating in immersion and scratch experiments was derived from the inert protective layer formed by the reaction of the rapidly released corrosion inhibitor with the corrosion products on the metal surface. After 30 days of immersion experiment, the coating could still maintain the low-frequency impedance value of 6.28 × 107 Ω cm2. In this work, the enhancement of the physical barrier function of HAp nanoparticle and the pH-response function conferred by β-cyclodextrin provided the coating with good passive and active acting abilities in corrosive environments, respectively.

Graphene oxide–polyamine preprogrammable nanoreactors with sensing capability for corrosion protection of materials

Corrosion is one of the major issues for sustainable manufacturing globally. The annual global cost of corrosion is US$2.5 trillion (approximately 3.4% of the world's GDP). The traditional ways of corrosion protection (such as barriers or inhibiting) are either not very effective (in the case of barrier protection) or excessively expensive (inhibiting). Here, we demonstrate a concept of nanoreactors, which are able to controllably release or adsorb protons or hydroxides directly on corrosion sites, hence, selectively regulating the corrosion reactions. A single nanoreactor comprises a nanocompartment wrapped around by a pH-sensing membrane represented, respectively, by a halloysite nanotube and a graphene oxide/polyamine envelope. A nanoreactor response is determined by the change of a signaling pH on a given corrosion site. The nanoreactors are self-assembled and suitable for mass-line production. The concept creates sustainable technology for developing smart anticorrosion coatings, which are nontoxic, selective, and inexpensive.

A multifunctional anticorrosive coating of hydroxyapatite platform based on metal-organic framework decoration with pH-responsive behavior

This study aimed to design a composite epoxy coating HZB/EP with pH-responsive behavior by grafting different material functions. In this approach, ZIF-8 particles were self-assembled on the surface of hydroxyapatite (HAp) through in situ growth, followed by encapsulation of the corrosion inhibitor BTA. Scanning electron microscopy (SEM) analysis of the coating section revealed a significant improvement in the dispersion of HZB in the resin compared to hydroxyapatite (HAp), resulting in a notable reduction in coating defects upon the addition of HZB. Electrochemical impedance spectroscopy (EIS) tests demonstrated that HZB/EP maintained a high low-frequency impedance value even after immersion in a 3.5% NaCl solution for 40 days, exhibiting an impedance magnitude 4–5 orders of magnitude higher than Pure EP. Additionally, scratch and salt spray tests validated the release and action process of the corrosion inhibitor BTA. This study presents a novel strategy for the development of multifunctional anticorrosive coatings.

Degradation Modeling and Lifetime Evaluation for Organic Anti-Corrosion Coatings Using a Three-Stage Electrochemical Statistical Model

Degradation Modeling and Lifetime Evaluation for Organic Anti-Corrosion Coatings Using a Three-Stage Electrochemical Statistical Model

Visualizing electrochemical zinc deposition and the role of a polymer additive in the crystal growth mechanism

AbstractElectrodeposition of metals is relevant to many research fields including catalysis, batteries, antifouling, and anticorrosion coatings. Compared with hot dip galvanizing, there is significant interest in less energy and material‐intense electroplating of zinc. At present, large‐scale electroplating mostly uses acidic zinc solutions, containing potentially toxic additives. Alkaline electroplating of zinc offers a route to using environment‐friendly green additives. Further to the previous elucidation of the mechanism by which the polyquarternium polymer (PQ) aids the deposition of negatively charged zincate, here the nature of the coating is explored. Zinc was deposited from an electrolyte including zincate and PQ, on gold model surfaces. Atomic force microscopy (AFM) and low energy ion scattering have been used to characterize the layer and explore the crystal growth mechanism that the PQ changes and, hence, improves the coating quality. We have also used AFM of the PQ on negatively charged mica to provide further evidence for the growth mechanism interpretation. Our data demonstrate that the additive is crucial to steering the growth mechanism, offering routes to optimizing deposition.

Functional Polymer Nanocomposites with Increased Anticorrosion Properties and Wear Resistance for Water Transport.

Corrosive destruction and hydroabrasive wear is a serious problem in the operation of machine parts and water transport mechanisms. It is promising to develop new composite materials with improved properties to increase the reliability of transport vehicles. In this regard, the use of new polymer-based materials, which are characterized by improved anticorrosion properties and wear resistance, is promising. In this work, therefore, for the formation of multifunctional protective coatings, epoxy dian oligomer brand ED-20, polyethylene polyamine (PEPA) hardener, a mixture of nanodispersed compounds with a dispersion of 30-90 nm, fillers Agocel S-2000 and Waltrop with a dispersion of 8-12 μm, and particles of iron slag with a dispersion of 60-63 μm are used for the formation of multifunctional protective coatings. Using the method of mathematically planning the experiment, the content of additives of different physico-chemical natures in the epoxy binder is optimized to obtain fireproof coatings with improved operational characteristics. A mathematical model is developed for optimizing the content of components in the formation of protective anticorrosion and wear-resistant coatings for means of transport as a result of the complex effect of a mixture of nanodispersed compounds, iron scale, and Waltrop. Based on the mathematical planning of the experiment, new regularities of increasing the corrosion resistance and resources of the means of transport are established through the formation of four different protective coatings, which are tested for resistance to aggressive environments (technical water-CAS No. 7732-18-5, gasoline-CAS No. 64742-82-1, acetone-CAS No. 67-64-1, I-20A lubricant-CAS No. 64742-62-7, sodium solutions-CAS No. 1310-73-2, and sulfuric acid-CAS No. 7664-93-9) and hydroabrasive wear resistances. A study of the change in the permeability index in aggressive environments is additionally carried out, taking into account the rational ratio of dispersive fillers in the epoxy binder, which made it possible to create an effective barrier to the penetration of aggressive water molecules into the base. A decrease in the permeability of protective coatings by 2.0-3.3 times relative to the epoxy matrix is achieved. In addition, the wear resistance of the developed materials under the action of hydroabrasion is investigated. The relative resistance of the CM to the action of hydroabrasion was found by the method of materials and coatings testing on the gas-abrasive wear with a centrifugal accelerator. This method enables one to model the real process of the wear of mechanism parts under the hydroabrasive action. It is shown that the coefficient of the wear resistance of the developed materials is 1.3 times higher than that of the polymer matrix, which indicates the resistance of the composites to the influence of hydroabrasive environment. As a result, modified epoxy composite protective coatings with improved anticorrosion properties and wear resistance under hydroabrasive conditions are developed. It is established that the protective coating filled with particles of a mixture of nanodispersed compounds (30-90 nm), iron scale (60-63 μm), and Waltrop (8-12 μm) has the lowest permeability indicators. The permeability in natural conditions of such a coating during the time t = 300 days of the study is χ = 0.5%, which is 3.6 times less than the similar indicators of the epoxy matrix. It is substantiated that the protective coating filled with particles of a mixture of nanodispersed compounds (30-90 nm), iron scale (60-63 μm), and Agocel S-2000 (8-12 μm) is characterized by the highest indicators of wear resistance. The coefficient of wear resistance under the action of hydroabrasion of such a coating is K = 1.75, which is 1.3 times higher than the similar indicators of the original epoxy matrix.

Cerium Methacrylate Assisted Preparation of Highly Thermally Conductive and Anticorrosive Multifunctional Coatings for Heat Conduction Metals Protection

HighlightsCerium methacrylate was prepared and ingeniously used as curing agent for epoxy, surface modifier for BN, and effective corrosion inhibitor.The coating integrates high thermal conductivity (4.29 W m−1 K−1), corrosion resistance (low-frequency impedance is 5.1 × 1011 Ω cm2 at 181 day), hydrophobicity (WCA: ~ 148.35° and WSA: ~ 20°), temperature resistance and adhesion.The coating can extend service life of metal materials without sacrificing their inherent heat conduction property.

THE USE OF INTERNALMULTIFUNCTIONAL COATINGS FOR PUMP AND COMPRESSOR PIPES TO PROTECT AGAINST THE FORMATION OF ASPHALT, RESIN AND PARAFFIN DEPOSITS

Along with the corrosive effect on downhole equipment, including pumping and compressor pipes (tubing), one of the main complicating factors in oil production is the formation of asphalt-resin-paraffin deposits (ARPDs) on the inner surface of the tubing. As in the case of corrosion protection, among the various methods of preventing the formation of ARPDs, the use of appropriate protective coatings has the greatest potential and is a valuable method because of its simplicity, efficiency and durability. At the same time, the use of manufactured anticorrosive coatings, that is, in essence, multifunctional protective coatings, is especially attractive for protection against ARPDs. But for this it is necessary to know the ability of existing multifunctional coatings to prevent the formation of ARPDs, to be able to correctly determine this ability. This article presents the results of research on the influence of the properties of the internal multifunctional coatings of tubing on the formation of ARPDs from the oil environment. At the same time, both the previously obtained results on the influence of coating properties determined in static conditions of absence or stationary oil medium (roughness, adhesion of paraffin to dry coating, edge angles of wetting with distilled water in air and oil in an aqueous medium) and new results on the study of the effectiveness of the use of internal functional coatings to protect tubing from formation of ARPDs in dynamic conditions of a moving oil medium (influence of the temperature gradient, the flow rate and duration of the coating in the oil environment) using laboratory circulation stands developed with the participation of the authors of the article, which allow modeling the processes of ASF deposition on the inner surface of the tubing in conditions closest to borehole conditions, are considered. Three commercially available internal coatings on tubing for corrosion protection and ARPDs are considered: a silicate-enamel coating of the MK-5 brand and filled polymer coatings of the MPLAG 17 and GIOTEK 110 M brands based on epoxyphenolic polymers. It is shown that testing on the developed laboratory circulation stands allows the most reliable assessment of the ability of internal multifunctional coatings to protect tubing from the formation of ARPDs in borehole conditions.

Self-healing anticorrosive coatings inspired by the biomimetic porous organic cage nanocontainer for mussels

In harsh corrosive environments such as deep sea, it cannot meet the requirements of long-term anticorrosion by uniquely increasing the physical barrier property of a coating with lamellar Ti3C2Tx nanosheets. Thus, it is quite desirable to acquire exciting anticorrosion applications through a skillful combination of a self-healing property with the physical barrier property of lamellar nanosheets. Inspired by the adhesion mechanisms of mussels, we successfully fabricated a porous organic cage (HNQ-EN) with adhesive nature as a nanocontainer. It could easily combine with Ti3C2Tx nanosheets and advance the compatibility between Ti3C2Tx and organic resin. Meantime, the porous structure of HNQ-EN enables it to accommodate various guest molecules, such as green cerium nitrate corrosion inhibitor. The introduction of HE-Ti3C2Tx-Ce in 3.5 wt% NaCl solution made the inhibition efficiency from the initial 7.8% increase to 91.1% after immersion for 36 h. It derived from the successful release of Ce3+ from HNQ-EN and forming cerium deposited film. For the composite coating containing HE-Ti3C2Tx-Ce (EP/HE-Ti3C2Tx-Ce), the LEIS results demonstrated it showed self-healing performance provided by Ce3+. Moreover, the lowest Zf = 0.01 Hz value for EP/HE-Ti3C2Tx-Ce coating reached 4.41 × 106 Ω cm2 after immersion for 36 h, which was one magnitude larger than that of EP coating.

POLYETHYLENE GAS PIPELINES: PROBLEMS AND EXPERIENCE OF TECHNICAL DIAGNOSTICS

More and more often in various industries, polymer materials are replacing metal structures. The gas industry is no exception, one of the areas of development of which was the introduction of polyethylene pipes to replace traditional steel pipes. This process began more than half a century ago, and according to data at the beginning of 2023, polyethylene pipes account for about 49.5 % of the length of all underground gas pipelines of gas distribution networks.
 The main obvious advantage of polyethylene pipes over steel pipes is corrosion resistance, which allows them to be operated without the use of protective anticorrosive coatings and electrochemical protection means. The strength properties of polyethylene pipes allow their operation at gas pressure up to 1.2 MPa, which makes it possible to almost fully meet the needs of the gas distribution sphere. The welding technologies of polyethylene pipes are well developed, standardized and automated.
 An important problem for long-term operating polyethylene gas pipelines is the assessment of their technical condition and determination of the residual life. Despite the existing need for work of this kind (for example, in 2022 only in the territory of the Saratov region it was required to carry out technical diagnostics of 8 gas pipelines with a total length of 39.86 km), expert organizations do not have the necessary tool for implementing this task today. Although the mechanism of aging of polyethylene is well known, there are no generally accepted standards for assessing the performance of polyethylene gas pipelines based on a comprehensive accounting of the influence of aging factors that determine their technical condition.
 The purpose of this article is to highlight the experience of Giproniigaz JSC in technical diagnostics of polyethylene gas pipelines, as well as to draw the attention of specialists from both the gas industry and academic science to the problem of developing a methodology for technical diagnostics of polyethylene gas pipelines.

Feasibility of using iron-rich phosphoaluminate cement to prepare anti-corrosive coatings for rebars

The anti-corrosive coating has been taken as an effective measure to keep rebars from corrosion. In this study, the iron-rich phosphoaluminate cement (IR-PAC) based anti-corrosive coating for rebar was prepared. The Cl- diffusion coefficient, strength against abrasion, and impact ductility of IR-PAC mortar were tested, with ordinary Portland cement (OPC) and sulphoaluminate cement (SAC) mortar as controls. The experimental results demonstrated that the chloride ion diffusion coefficient of IR-PAC was the lowest at any age. Compared with OPC and SAC, the strength against abrasion of IR-PAC at 90 d increased by 19.19 % and 14.32 %, respectively. The impact ductility of IR-PAC at 28 d increased by 28.21 % and 17.37 %, respectively. IR-PAC had good resistance to Cl- penetration, excellent strength against abrasion and impact ductility, which assisted the coating in blocking Cl- intrusion and resisting damage. The optimum SCMs based coating for rebar is as follows: 10.08 % Fly ash (FA), 0.1 % nano-silica (NS), and 0.65 % superplasticizer (SP). The coatings prepared with this formulation were used for electrochemical experiments. The rebars coated with IR- PAC had good corrosion resistance, which proved it is feasible to use IR-PAC to prepare anti-corrosive coatings for rebars.

Polysilazane Anti-corrosion Coating that Can Replace Hot-dip Galvanizing

In response to the problems of high energy consumption and pollution and insufficient anti-corrosion performance in the preparation process of hot-dip galvanized anti-corrosion materials, a polysilicon nitride anti-corrosion coating was developed. Using vinyl polysilazane as the base resin and adding zinc powder antirust pigment to the resin, a polysilazane zinc-rich anticorrosion coating was developed. The performance of the coating was characterized, and the results showed that the coating had a hardness of 6 H after heat treatment at 250°C and a salt spray resistance better than that of hot-dip zinc samples. 2000 h of salt spray resistance after heat treatment at 600°C, which is twice that of hot-dip galvanized materials, and the scratches are self-healing. The coating is a good substitute for hot-dip galvanized material.

Ultrafast synthesis of novel coal-based graphene and its anticorrosion properties of epoxy/graphene nanocomposite coatings

Graphene has a wide range of applications in anti-corrosion coatings due to its excellent barrier, shielding, and mechanical properties. However, traditional graphene synthesis methods, including the production of graphene oxide (GO) using Homer's method and then its reduction in the form of reduced graphene oxide (rGO) are time-consuming, energy-consuming, and environmentally polluting, which limits their application in anti-corrosion coatings. This study leveraged the capabilities of flash Joule heating (FJH) to synthesize flash coal-based graphene (FCBG) from Taixi anthracite (TA) within 200 ms without pretreatments or chemical reagents. The FJH had the advantages of low energy consumption and being environmentally friendly. Compared with the rGO, the FCBG prepared by FJH was characterized by fewer defects, larger carbon sheets, and a turbostratic structure. Moreover, carbon steel Q235 was used as the substrate to prepare anti-corrosion coatings by mixing FCBG at different flash voltages with epoxy resin (EP). Based on this, the electrochemical performance of different coatings was compared before and after salt spray corrosion. The results demonstrated that the FCBG composite anti-corrosion coating (EP/FCBG190) prepared using EP and FCBG synthesized at 190 V in the FJH, displayed stronger corrosion resistance than the EP and rGO composite coating (EP/rGO). The FJH synthesis process provides a feasible route for improving the synthesis process of the anti-corrosion coatings and the high value-added utilization of coal.

Functional partition strategy in assistance by shear thinning/self-healing effect to prepare durable anti-corrosion coating

The application of self-healing polymers in anti-corrosion coatings is restricted by their nonautonomous healing ability and poor long-term durability. In this paper, we propose a functional partition strategy assisted by the shear thinning effect to overcome the above restriction. The shear thinning effect was achieved by preparing a branched ethyl acrylate-acrylonitrile copolymer (B-PEA). The B-PEA coating exhibits multiple autonomous self-healability at room temperature (1.5 h) and in a salt solution (2 h), with a high adhesion strength of 3.4 MPa. To further improve the performance, a functional partition architecture combining superhydrophobic barrier and self-healing multilayers was constructed. The introduction of the superhydrophobic barrier layer largely increases the low-frequency impedance modulus |Z|f-0.01Hz and salt solution resistance time to 3.9 × 1010 Ω⋅cm2 and 3600 h, respectively, compared to a pristine B-PEA coating. The introduction of the B-PEA layer provides the barrier layer with room-temperature self-healing ability (2 h), and increases the long-term |Z|f-0.01Hz and salt solution resistance time in the presence of scratches to 7.7 × 109 Ω⋅cm2 and > 3600 h, respectively. The as-prepared superhydrophobic anti-corrosion coating system combines long-term durability and room-temperature autonomous self-healability in harsh salt-solution environments, and thus has a high potential for anti-corrosion applications.

Design, synthesis, and evaluation of high‐performing anticorrosive polyurethane coatings with inbuilt redoxable oligomeric aniline segments

AbstractThis paper presents, a facile route for the synthesis of electroactive hybrid polyurethane‐urea's (EPUU) using back‐bone modification with diamine‐capped trianiline (DCTA) and diamine‐capped tetraaniline (DCTAni) oligomers. These EPUUs were loaded with different weight percentages (12.5, 25, and 50) of DCTA and DCTAni and named PU‐DCTA (12.5, 25, and 50) and PU‐DCTAni (12.5, 25, and 50), respectively. The formation of oligomers and their EPUUs were confirmed by using formal characterizations such as FTIR, HRMS, UV–Visible spectroscopies, and electrochemical studies. TGA, DSC, and tensile studies were conducted on the cured films to better understand the structure and property relations. The mechanical and thermal properties of EPUU films are as high as 60.0 MPa tensile strength and T5% at 322°C, and the adhesion strength of 300‐μm films on mild steel was observed as 533 psi. Tafel polarization and electrochemical impedance spectroscopy (EIS) measurements were used to determine these polymers' anti‐corrosive capabilities. An accelerated salt‐spray test that revealed the coatings are stable for up to 600 h when exposed to 5% NaCl fog. The high corrosion resistance observed for PU‐DCTAni was found to be 6.874 × 10−6 mm/year from the Tafel polarization test, and its high polarization resistance was found to be up to 55.912 MΩ.

Outstanding thermally conductive and anticorrosive polymer composite coating via a multifunctional epoxy curing agent zinc dimethacrylate

Highly thermally conductive metallic materials show great promise in thermal management field. Whereas, inherently high susceptibility of metal materials to corrosion medium would shorten service life and affect heat transfer properties of corresponding materials, thus invalidating their applicability to thermal management devices. This study solves this by preparing an epoxy composite coating with integrated high thermal conductivity (TC) and well long-term corrosion protection performance via synthesizing zinc dimethacrylate (ZDMA) as a novel multifunctional epoxy resin curing agent and designing “point-surface” heterostructure of recrystallized ZDMA nanoparticles-modified boron nitride (BN) sheet with both thermally conductive and anticorrosive functions. The findings reveal that the “double bridging effect” provided by ZDMA and well-dispersed filler result in the formation of efficient heat conduction pathways and barrier effect in the coating. The final coating (h-ZBN/Z/EP) exhibits a high TC of 2.55 W/(m·K), which is more than 11 times that of pure epoxy coating and is much higher than the TC reported for other anti-corrosion polymer coatings. Case calculation and finite element simulation show that the coating can maintain well heat transfer performance of the coated metal material compared to pure epoxy coating. Further combined with the corrosion inhibitory effect of Zn2+ ions, the low-frequency impedance of h-ZBN/Z/EP coating is still as high as 1.32 × 1011 ohm·cm2 after immersion in 3.5 wt% NaCl solution for 360 days. This ingenious strategy provides a fascinating and simple method for preparing multifunctional composite coatings used for long-term protection of heat conduction metallic materials.