Polymer Coatings Research Articles

Film thickness characterization in dual-axis spin coating of a sphere

The versatility of spin coating technology makes it a preferred method for producing the thin film layers used to manufacture products from solar panels and smartphones to sunglasses and CDs. However, the process requires a flat, rigid substrate to produce uniform films, which limits its use to planar devices. A novel multi-axis manipulator has been developed to extend the application of spin coating, enabling controlled thin film deposition onto curved surfaces. Various rotational schemes were studied to link the flow of a liquid film over a curved surface to forces induced by complex rotational dynamics. When the angular velocity exceeds a threshold, centrifugal force dominates the flow, pushing the fluid away from the instantaneous axis of rotation. This produces axisymmetric coating profiles when using consistent single or dual-axis rotation. Areas of near uniformity present around the spin axis poles for single-axis rotation and around the substrate’s equator for dual-axis schemes. Sensitivities between the spherical substrate dynamics and the evolving fluid flow were investigated, exploring the parameters that promoted the production of uniform curved film layers for microfabrication processes. This enabled the evolution of the spin coating technique to effectively form curved polymer coatings with improved thickness control. The presented research outlines the capabilities of a multi-axis spin coating machine when used to coat spherical substrates. Therefore, enabling the use of fluid mechanics models to identify the optimal motion kinematics required to create uniform curved films.

Polymer Coating Technique Using Surface-Forming Radicals

Polymer Coating Technique Using Surface-Forming Radicals

Artificial Spores as Multi‐Functional Biocatalysts to Perform Biosynthetic Cascades

AbstractCells exhibit diverse structural formations such as biofilms and spores, enabling them to acquire novel functionalities. Many of these structures display biomacromolecules, including enzymes, tethered to cell walls to support various extracellular processes. Alternatively, encapsulating single cells with polymer coatings offers a strategy that circumvents the need for genetic engineering while imparting artificial functionalities to cells. Here, a universal method is presented for encapsulating single gram‐negative microbes with polymeric coatings based on the ancestral gall ink formed by tannic acid‐iron complexes. As a result, synthetic spores are achieved that selectively bind His‐tagged enzymes through the formation of unprecedented galloyl/imidazole‐Fe2+ complexes via ligand substitution demonstrated by density functional theory. These synthetic spores with a thickness of 41.5 ± 4.2 nm and a stiffness of 6.0 ± 3.5 GPa serve as biocatalytic materials for the one‐pot oxidative amination of diols into amino alcohols, facilitated by the cooperative catalysis between intracellular endogenous or recombinant oxidoreductases, and an extracellular transaminase from Pseudomonas fluorescens displayed at the spore surface. These spores maintain their performance in three consecutive batch cycles. Integrating isolated enzymes onto the surface of engineered microbes coated with polymers offers novel opportunities for synthetic biology, advancing the efficiency of biosynthetic cascades in solid‐state environments.

A Mechanical Strength-Enhanced Polymer Coating with Anion-Phobic and Solvent-Phobic Capability for Advanced Lithium Metal Anodes

A Mechanical Strength-Enhanced Polymer Coating with Anion-Phobic and Solvent-Phobic Capability for Advanced Lithium Metal Anodes

Synthesis of Ag@SiO2 core-shell nanoparticles for antibacterial application in water-based acrylic polymer coatings

In this study, Ag@SiO2 core-shell nanoparticles were synthesized using the Stöber method and then physically mixing with MPS functionalized poly (styrene-co-acrylate) (PSA) emulsion to obtain a novel antibacterial composite material (PSA/Ag@SiO2). The dispersion of composite latexes was improved by the formation of Si-O-Si covalent bonds, and the migration of AgNPs on the surface of composite films enhanced their antimicrobial activity. Analysis of UV-Vis absorption spectra, TEM images, XPS and XRD data confirmed the core-shell structure of Ag@SiO2 and the successful coating of AgNPs by SiO2. TEM micrographs showed that Ag@SiO2 core-shell nanoparticles were uniformly dispersed in the composite latexes, with an average particle size of 198 nm for PSA/Ag@SiO2 composite latexes, larger than that of PSA latexes (162 nm). FTIR spectra also indicated the presence of Si-O-Si covalent bonds resulting from the sol-gel reaction between MPS functionalized PSA with Ag@SiO2. XPS and WCA characterization revealed the disruption of the core-shell structure of Ag@SiO2, leading to the migration of AgNPs to the air-film interface. The results of antibacterial activity demonstrated that PSA/Ag@SiO2 composite films displayed antibacterial activity against both E. coli and S. aureus, and the former displayer a slightly better antibacterial activity than the latter. The water-based acrylic polymer coatings with antibacterial properties explored in current work have various applications in wood paints, varnishes, metal protection, decorative systems and other related fields.

Ultra-high capacity and anti-interference for Cr(VI) removal by tannin-polyvinylimine modified graphite carbon nitride

To combat the increasingly serious water pollution caused by heavy metal ions, the development of efficient adsorbents is of great significance. In this study, a novel composite adsorbent for Cr(VI) removal was smartly designed using environmentally friendly materials such as tannic acid (TA) and polyethyleneimine (PEI) for surface modification of g-C3N4 nanosheets through covalent assembly of polyphenols and amines. The obtained (PEI-TA)-g-C3N4 composite was capable of efficiently and quickly adsorbing Cr(VI) in water, with a maximum adsorption capacity of 769.23 mg/g at 308 K (35 °C), which was much higher than most reported Cr(VI) adsorbents. Notably, (PEI-TA)-g-C3N4 could reduce highly toxic Cr(VI) to low toxic Cr(III) and effectively adsorb it. The Cr(VI) adsorption process was a spontaneous thermal adsorption process that conformed to the pseudo-second-order kinetic model and Langmuir isotherm model. In addition, the excellent photothermal performance of (PEI-TA)-g-C3N4 further accelerated the adsorption of Cr(VI). Moreover, the strong anti-interference ability of (PEI-TA)-g-C3N4 composite against anions and other metal ions enabled it to effectively remove Cr(VI) in complex environments, expanding its practical application scenarios. The polymer coatings rich in phenolic hydroxyl- and amine-rich formed on the large surface area of g-C3N4 and the protonation of the amino groups are the keys for (PEI-TA)-g-C3N4 composite to have ultra-high adsorption performance and strong anti-interference ability towards Cr(VI). The designed strategy of this metal-free and environmentally friendly composite with ultra-high removal of Cr(VI) capability from wastewater provides new ideas for developing green, inexpensive, and efficient adsorbents.

Long-lasting renewable antibacterial N-halamine coating enable dental unit waterlines to prevention and control of contamination of dental treatment water

Developing bacterial biofilm on the dental unit waterlines increases the risk of cross-infection among oral patients. Although chemical disinfectants can achieve disinfection effects in a short period of time, corrosion damage of dental unit waterlines and water contamination can also occur after continuous use of it. Herein, this study explored a one-step deposition method to prepare a durable and renewable antibacterial N-halamine polymeric coating on polyurethane waterlines. The method utilized polyelectrolyte complexes formed with polyethylenimine (PEI) and phytic acid (PA), followed by chlorination to activate the antibacterial properties. The N-halamine polymeric coating reduces the polyurethane waterline’s water contact angle, thus reducing biofouling deposits and the obstruction of the active halide site on the waterlines, thereby facilitating the maintenance of the cleanliness of the coating. In addition, benefiting both from the active chlorine release and the high density of positive charges on the coating, the polyurethane waterline antimicrobial activity is significantly enhanced. Besides, the N-halamine polymeric coating is biocompatible. This study showed that long-lasting and renewable antimicrobial requirements can be achieved by simple surface modification of N-halamine polymer coatings, which provides a practicable strategy for the production of long-term and reproducible antibacterial dental unit waterlines to reduce the incidence of hospital infection in oral department.

Super‐liquid‐repellent thin film materials for low temperature latent heat thermal energy storage: A comprehensive review of materials for dip‐coating

AbstractWhen discharging latent heat thermal energy storage (LHTES) systems, performance is influenced by the formation and adherence of a solid layer of phase change material (PCM) on heat eXchange (HX) surfaces. Super‐liquid‐repellent thin films (STFs) may be able to reduce solidifying PCM adhesion on HX surfaces during discharging, delay PCM solidification to lower temperatures, and by modifying nucleation sites potentially enable long‐term seasonal thermal storage. Techniques employed previously to fabricate sintered polymeric STF coatings include chemical vapour deposition, dip‐coating, spray‐coating, spin‐coating, layer‐by‐layer (LbL) assembly, sol‐gel, anodizing, electrodeposition, electrospinning, so on. Dip‐coating is considered attractive for fabricating thin films on simple and complex surface geometries due to process maturity, scalability, flexibility and cost‐effectiveness. To identify suitable materials for preparing STFs on metal HX surfaces using the dip‐coating process, more than 200 journal articles published in English during the period 2010 to 2022 were reviewed and the potential role of STFs in LHTES applications was assessed. The review identified key areas and applications stimulating STF material developments and formulations. The dip‐coating of potential STF materials was classified under three major themes driving current research and development (R&D) activities, that is, high performance thin films, eco‐friendly thin films and fundamental research formulations. This review provides a platform from which to develop coatings and HX systems to enable the cost‐effective implementation of STFs for improved heat transfer in future mobile/stationery LHTES systems.

Destruction of Internal Anticorrosive Polymer Coatings of Oilfield Pipes during Operation

Introduction. Failure of equipment, specifically pipes in the oilfield complex, due to the development of corrosion processes leads to numerous losses, destruction of expensive components, disruption of technological processes and, as a result, environmental damage. The use of anticorrosive coatings as an internal protection of oilfield pipes offers many advantages and can significantly reduce the rate of corrosion, but does not provide a complete solution to this problem. Destruction of internal anticorrosive polymer coatings (IACPC) occurs for numerous reasons. The causes and mechanisms of destruction are insufficiently investigated. Therefore, the aim of this work was to analyze the destruction of internal anticorrosive polymer coatings using practical examples, which made it possible to form and identify the main causes of damage and degradation of coatings during operation.Materials and Methods. A complex of laboratory studies was carried out to study the damage to internal polymer anticorrosive coatings during operation and to establish the main causes of destruction. The initial phase of the investigation involved a detailed examination of the materials related to the accident circumstances, including the operating conditions of the coated pipeline (composition of the operating medium, temperature, pressure, and presence of mechanical impurities), operation time, and type of polymeric material used. The second phase involved laboratory testing of the coating, which included the determination of layer thickness, dielectric continuity, adhesive strength (by the normal separation method), investigation of thermokinetic properties by means of differential scanning callometry (DSC), study of the coating structure using scanning electron microscopy.Results. Practical examples of the destruction of internal anticorrosive coatings of oilfield pipes were analyzed. For each case, characteristic signs of degradation of the anti-corrosive coating were identified. Changes in the microstructure of the coatings, as well as the formation of corrosion products, were observed depending on the type of destruction. The focus was on studying the degree of polymerization of the coating, both using the traditional method of determining the ΔTg parameter using DSC, and based on indirect signs detected during microscopic studies.Discussion and Conclusion. The practical cases of damage to the internal anticorrosion coating of pipes of the oil and gas complex considered in the article allowed us to divide the causes of destruction into three groups: operational, technological and defects during transportation, storage and construction and installation works. Based on these findings, we have formulated recommendations for manufacturers to ensure maximum performance from their coatings. It is noted that the compliance with the presented recommendations makes it possible to obtain internal anticorrosive polymer coatings with a minimum guaranteed lifespan of 15 years, as demonstrated by the successful operations of pipelines in Western Siberia, such as those operated by Surgutneftegaz PJSC and LUKOIL – Western Siberia LLC.

Fabrication and properties of recyclable tung oil–based polymer coatings based on dual cross-linked dynamic covalent polymer networks

The exploration of reprocessability and high-adhesion biomass polymer coatings is in line with the concept of green materials and is conducive to energy conservation and environmental protection. Here, a series of novel recyclable tung oil–based polymer coatings based on dual cross-linked dynamic covalent networks were reported. Tung oil polymerized maleic anhydride (TOA) was firstly prepared and further reacted with furfuryl alcohol. Then tung oil-polymerized maleic furanol ester (TOAFA) containing reactive conjugated double bond and carboxyl groups was prepared. FTIR and 1H NMR demonstrated the reactive monomer TOAFA was successfully synthesized. Then TOAFA was cross-linked with bismaleimide and different epoxy resins to fabricate target polymer networks based on dynamic Diels-Alder(D-A) bonds and dynamic transesterification. The shape memory, reprocessing, and mechanical and thermal stability of the copolymerized systems with different crosslinking states were investigated. The coating performances were characterized with solvent resistance, adhesion strength, hardness and glossiness tests. It was found that the dynamic D-A covalent bonds were perfectly combined with transesterification in the polymerization systems. The copolymerized systems possessed excellent thermal stability and mechanical properties. The rigid and flexible properties of the polymer networks can be controlled by adjusting the component weight ratios and the type of epoxy resin in the polymerization system. The rigid polymerization system had the highest tensile strength of 28 MPa, and its elongation at break was up to 57 % of the flexible polymerization system. Coating adhesion test showed the adhesion property reached level 1. The polymer coatings displayed excellent solvent corrosion resistance, and relative high gloss. The polymer networks also showed certain reprocessing performance and excellent shape memory effect.

Discontinuous Shear Thickening of Suspensions of Magnetic Particles in Relation to the Polymer Coating on Their Surfaces

The phenomenon of discontinuous shear thickening (DST) is observed in suspensions of solid particles with a very high-volume fraction. It is characterized by an abrupt decrease in the shear rate for critical stress during a ramp of stress. This behavior can be reproduced in numerical simulations by introducing a local friction between two particles above a given local force. We present experimental results showing this DST behavior obtained with suspensions of magnetic (iron) and nonmagnetic (calcium carbonate) particles and different amounts of a superplasticizer molecule used in the cement industry. For both types of particles, the same behavior was observed with first an increase in critical stress with the amount of plasticizer followed by a decrease at higher concentrations but with a larger viscosity before critical stress was reached. At a low concentration of plasticizer, the low critical stress is interpreted by the local sliding of plasticizer molecules on the surface of particles. At higher concentrations, when total coverage is achieved, the critical stress is higher since it has to remove the molecules out of the surface. At still higher concentrations, the increase in viscosity is explained by the formation of multilayers of molecules on the surface of the particles. This interpretation is supported by the measurement of the adsorption isotherm of the plasticizer on the surface of the particles.

Simple Encoded Circularly Polarized Protein Lighting

AbstractLighting systems with circularly polarized luminescence (CPL) are an emerging field with high hopes in, for example, neural cell circuits and encoding applications. The major challenges that forfeits their real‐world application are i) the design of chiroptical materials (CMs) with high CPL brightness (BCPL; today's record is Eu‐based compounds with average 287 M−1cm−1, while 90% of other CMs show <150 M−1cm−1 in solution) and ii) how to keep CPL response in films/coatings of technological relevance. Since natural evolution is driven by chiral selectivity at the supramolecular level, fluorescent proteins (FPs) are ideal candidates to provide large BCPL spanning visible and near‐infrared regions. This hypothesis is confirmed for all the known FP classes, demonstrating high emission intensities (photoluminescence quantum yields (ϕ) up to 76%) and record average BCPL of |200| M−1cm−1 (solution). What is more, the CPL response is also kept in polymer coatings. It is rationalized that structural factors (chromophore rigidity, surrounding amino acids, supramolecular packaging, and exciton coupling) hold a significant influence, regardless of the ϕ values. Finally, proof‐of‐concept CPL‐encoded signals in monochromatic/white hybrid light‐emitting diodes with FP‐polymer filters show exceptional stabilities. Overall, this work stands out FPs toward a new CM family, in general, and biogenic CPL‐encoded lighting systems, in particular.

Antimicrobial polymeric coatings synthesized by solvent-free initiated Chemical Vapor Deposition: A review

Microbial adhesion on surfaces may cause infectious diseases that seriously threaten human health, which can be controlled by antimicrobial surfaces. Antimicrobial polymeric coatings can endow surfaces with biocidal properties to address infectious diseases. Initiated Chemical Vapor Deposition (iCVD) is a novel technique to synthesize high-quality polymeric antimicrobial coatings on various surfaces. Owing to the solvent-free and mild deposition conditions, iCVD facilitates solvent-susceptible, delicate, or fragile substrates. Herein, we provided a comprehensive review of antimicrobial coatings fabricated by iCVD. First, iCVD was introduced. Then, antimicrobial iCVD coatings were discussed based on killing and antifouling strategies. The microbe-killing coatings were discussed according to release-killing and contact-killing approaches. Next, hydrophilic, hydrophobic, and amphiphilic antifouling coatings were reviewed. Finally, micro/nano-structured antimicrobial surfaces fabricated via iCVD were also discussed, followed by the future directions of iCVD coatings in the antimicrobial field.

Roughness-Mediated SI-Fe0CRP for Polymer Brush Engineering toward Superior Drag Reduction.

Surface-initiated iron(0)-mediated controlled radical polymerization (SI-Fe0CRP) with low toxicity and excellent biocompatibility is promising for the fabrication of biofunctional polymer coatings. However, the development of Fe(0)-based catalysts remains limited by the lower dissociation activity of the Fe(0) surface in comparison to Cu(0). Here, we found that, by simply polishing the Fe(0) plate surface with sandpaper, the poly(methacryloyloxy)ethyl trimethylammonium chloride brush growth rate has been increased significantly to 3.3 from 0.14 nm min-1 of the pristine Fe(0) plate. The excellent controllability of roughness-mediated SI-Fe0CRP can be demonstrated by customizing multicompartment brushes and triblock brushes. Furthermore, we found that the resulting polymer brush coatings exhibit remarkably low water adhesion (0.097 mN) and an outstanding drag reduction rate of 52% in water. This work provides a promising strategy for regulating the grafting rate of polymer brushes via SI-Fe0CRP for biocompatible marine drag reduction coatings.

Thickness Variation of Conductive Polymer Coatings on Si Anodes for the Improved Cycling Stability in Full Pouch Cells.

Si-dominant anodes for Li-ion batteries provide very high gravimetric and volumetric capacity but suffer from low cycling stability due to an unstable solid electrolyte interphase (SEI). In this work, we improved the cycling performance of Si/NCM pouch cells by coating the Si anodes with the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) prior to cell assembly via an electropolymerization process. The thicknesses of the PEDOT coatings could be adjusted by a facile process parameter variation. Glow-discharge optical emission spectroscopy was used to determine the coating thicknesses on the electrodes prior to the cell assembly. During electrochemical testing, improvements were observed closely linked to the PEDOT coating thickness. Specifically, thinner PEDOT coatings exhibited a higher capacity retention and lower internal resistance in the corresponding pouch cells. For the thinnest coatings, the cell lifetime was 18% higher compared to that of uncoated Si anodes. Postmortem analyses via X-ray photoelectron spectroscopy and cross-sectional scanning electron microscopy revealed a better-maintained microstructure and a chemically different SEI for the PEDOT-coated anodes.

Polysaccharide-Based Edible Biopolymer-Based Coatings for Fruit Preservation: A Review

Over the last decades, a significant rise in fruit consumption has been noticed as they contain numerous nutritional components, which has led to the rise in fruit production globally. However, fruits are highly liable to spoilage in nature and remain vulnerable to losses during the storage and preservation stages. Therefore, it is crucial to enhance the storage life and safeness of fruits for the consumers. To keep up the grade and prolong storage duration, various techniques are employed in the food sector. Among these, biopolymer coatings have gained widespread acceptance due to their improved characteristics and ideal substitution for synthetic polymer coatings. As there is concern regarding the safety of the consumers and sustainability, edible coatings have become a selective substitution for nurturing fruit quality and preventing decay. The application of polysaccharide-based edible coatings offers a versatile solution to prevent the passage of moisture, gases, and pathogens, which are considered major threats to fruit deterioration. Different polysaccharide substances such as chitin, pectin, carrageenan, cellulose, starch, etc., are extensively used for preparing edible coatings for a wide array of fruits. The implementation of coatings provides better preservation of the fruits such as mango, strawberry, pineapple, apple, etc. Furthermore, the inclusion of functional ingredients, including polyphenols, natural antioxidants, antimicrobials, and bio-nanomaterials, into the edible coating solution matrix adds to the nutritional, functional, and sensory attributes of the fruits. The blending of essential oil and active agents in polysaccharide-based coatings prevents the growth of food-borne pathogens and enhances the storage life of the pineapple, also improving the preservation of strawberries and mangoes. This paper aims to provide collective data regarding the utilization of polysaccharide-based edible coatings concerning their characteristics and advancements for fruit preservation.

Bio-inspired superhydrophobic fiber membrane for oil-water separation and non-destructive transport of liquids in corrosive environments

Conventional polymer separation membranes or coatings suffer from poor separation performance and serious failure in highly corrosive environments, due to their low chemical and mechanical stability. Herein, a simple electrospraying and electrospinning strategy was used to prepare flexible superhydrophobic carbon fiber membranes (FSCFM). The wettability of FSCFM was improved by forming a lotus leaf-like hierarchical rough structure on its surface. The FSCFM exhibited an excellent permeation flux of immiscible oil-water mixtures (up to 15,800 L m−2 h−1) and water-in-oil emulsions (over 5500 L m−2 h−1), while the separation efficiencies were always kept at more than 99 % after 25 consecutive separations. Even in corrosive environments, its separation performance did not show any degradation. Notably, except for recovering floating oil under external driving forces with excellent cyclic stabilities, FSCFM was also able to transport various corrosive solutions with high efficiencies (99.9 %). After multiple mechanical damages and bending cycles, the FSCFM remained superhydrophobic. It could also maintain its repellency in strong acids/bases, high salt solutions and even under high-temperature environments (94.5 °C). These superior properties make it a strong candidate for oil-water mixture/emulsion separation and non-destructive transport of highly corrosive fluids.

Hydrogel/MOF Dual-Modified Photoelectrochemical Biosensor for Antibiofouling and Biocompatible Dopamine Detection.

For accurate in vivo detection, nonspecific adsorption of biomacromolecules such as proteins and cells is a severe issue. The adsorption leads to electrode passivation, significantly compromising both the sensitivity and precision of sensing. Meanwhile, common antibiofouling modifications, such as polymer coatings, still grapple with issues related to biocompatibility, electrode passivation, and miniaturization. Herein, we propose a composite antibiofouling coating strategy based on zwitterionic metal-organic frameworks (Z-MOFs) and a combination of acrylamide hydrogels. On a well-designed TiO2/Z-MOF/hydrogel photoelectrode, we achieve highly sensitive and selective detection of dopamine in complex biological environments. The hydrogel's three-dimensional porous structure combined with unique microporous architecture of Z-MOF ensures effective sieving of interfering macromolecules while preserving efficient small molecules and electron transport. This innovative approach paves the way for constructing miniature, in vivo antibiofouling sensors for molecule monitoring in living organisms with complicated chemical environments.

Optimizing the preparation of polymer nanocoatings by self-assembly and gamma irradiation of elaidic acid on copper surfaces

Self-assembling molecular layers (SAMs) can serve as a densely packed film of monomers that can be easily crosslinked to form nanometer-thick polymer coatings with high protective properties. However, the properties of the resulting coatings are highly dependent on the preparation method used to apply the SAM to the surface.In this work, the influence of different SAM preparation steps (preparation of the oxide layer, self-assembly and drying) on the corrosion resistance of the coated samples, as well as the method of applying the molecules to the surface (immersion, spraying, brush application), was investigated. Elaidic acid, an unsaturated trans fatty acid, was applied to copper and crosslinked with gamma radiation. The properties of the coatings were studied by electrochemical methods, contact angle measurements, XPS, AFM and FTIR. The results show that the oxidation step is crucial for obtaining proper coatings, while the drying at elevated temperatures is not required. It has also been shown that the immersion of samples results in coatings with the best protective properties, while the application by brush can be an alternative method of application. On the other hand, spraying the elaidic acid results in a less uniform coating.

SYNTHESIS OF COPOLYMERS FOR PROTECTIVE COATINGS

Copolymers were obtained in this work and the methodology for their synthesis was worked out. Various fillers were selected for the polymer coating. Resulting copolymers have good adhesion required for composite protective coatings. An experiment was conducted to determine the corrosion resistance of metals coated with copolymers when exposed to aggressive environments, as well as to determine the hardness and thickness of the polymer coatings obtained. It was found that the polymer coating filled with bronze powder, despite the small thickness of 43.4 μm, hasthe best adhesion and corrosion properties, as well as having the highest hardness values of 80.5 HB. Such physical and mechanical properties of polymer coatings allow them to be used as protective coatings for metal products working under the influence of aggressive media.