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New Developments of Protective Coatings, Organic Polymers, and Surface Analysis: 2nd Edition

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A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Functional Polymer Coatings and Films".

Deadline for manuscript submissions: 24 October 2025 | Viewed by 20369

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Dr. Florina Branzoi

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Institute of Physical Chemistry of Romanian Academy, 202 Splaiul Independentei, Bucharest, Romania
Interests: organic polymers; corrosion; polymer coating; biomedical materials; surface
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Dear Colleagues,

In recent years, the protective coatings of organic polymers on active metals have been one of the most widely studied domains in the field of corrosion protection. Organic coatings are frequently used to protect metals and their alloys against corrosion, and they have attracted significant attention in the scientific and technological fields, as metals such as iron, zinc, aluminum, and magnesium and their alloys are widely employed in numerous practices. The fabrication, investigation, and testing of high-efficiency nanostructured materials that are electroactive (carbon nanotubes, conductive polymers, etc.), effective as protection layers (organic polymers, surfactants, nanocomposites materials, etc.), or have a combination of these traits help to ensure the exceptional functionality of these materials for multifunctional coatings. These coatings protect metallic substrates from corrosion in different aggressive media. The efficiency of these protective coatings in serving as a barrier for the substrate depends on numerous factors: the type of organic polymer, the electrodeposition method that has been used on the electrode’s surface, and the aggressive medium, etc. The synthesis of new organic composites from different monomer molecules has been realized to enhance the physicochemical properties of polymer coatings in order to increase their lifecycle, improve their adherence, and enhance their electrochemical properties. However, by identifying organic coatings that are suitable for electrodeposition, it is possible to increase the mechanical and protective properties of the polymer for utilization as an anticorrosive layer in different aggressive environments. Composite coatings are promising and might have industrial applications in protecting metallic substrates from corrosion.

This Special Issue invites papers that focus on, but are not limited to, the following topics: the theoretical and experimental study of organic coatings for corrosion protection; mechanisms and methods of corrosion control; new developments in organic coatings and related materials; chemical and physical properties of organic coatings and related materials; methods of preparation, fabrication, and application of organic coating materials for the protection of metallic substrates against corrosion; performance, investigation, and analysis of organic coatings; experimentation on and processing of high-efficiency coatings under high temperature, high stress, and different immersion times; computer modeling to provide coverage properties, performance, stability, and resistance in aggressive media.

Dr. Florina Branzoi
Guest Editor

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Keywords

organic coatings
nanocomposite film
electrodeposition
corrosion protection
electrochemical methods
corrosion inhibitor
surface analysis

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Published Papers (9 papers)

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Research

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27 pages, 9947 KiB

Open AccessArticle

Use of 2D Sulfide and Oxide Compounds as Functional Semiconducting Pigments in Protective Organic Coatings Containing Zinc Dust

by Miroslav Kohl, Karolína Boštíková, Stanislav Slang, Eva Schmidová and Andréa Kalendová

Coatings 2024, 14(8), 1009; https://doi.org/10.3390/coatings14081009 - 8 Aug 2024

Cited by 1 | Viewed by 1438

Abstract

Within this study, the influence of particles of different types, natures, and sizes on the mechanical and corrosion resistance of pigmented systems containing spherical zinc was studied. For this study, prominent representatives from the group of transition metal dichalcogenides (MoS₂, WS₂), layered transition metal oxides (MoO₃, WO₃), and other semiconductor materials (ZnS and ZnO) were used. The layered ultra-thin structure of these particles was predisposed to provide enhanced mechanical and anti-corrosion performance. The mechanical properties of the studied coatings were tested using standardized mechanical tests, while the anti-corrosion performance of these coatings was studied using standardized cyclic corrosion tests and the linear polarization electrochemical technique. The results of the experimental techniques bring completely original knowledge about the action of these pigments in paint systems pigmented with zinc. The results of experimental techniques have shown enhancement and an increase in both mechanical and anti-corrosion performance when using these special types of inorganic pigments. In particular, with organic coatings pigmented with MoO₃, there was an increase in mechanical resistance mainly due to its morphology and layered structure. In addition, a significant enhancement of the anti-corrosion efficiency was noted for this type of organic coating due to the enhancement of individual types of action mechanisms typical and proven for zinc-pigmented systems. These original findings can be used in the search for possibilities to reduce the zinc content in zinc-pigmented organic coatings. This partial replacement of zinc particles leads not only to a reduction in the zinc content in the system but also to a significant strengthening of the mechanical resistance and an increase in the corrosion efficiency of the system. Full article

(This article belongs to the Special Issue New Developments of Protective Coatings, Organic Polymers, and Surface Analysis: 2nd Edition)

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16 pages, 8598 KiB

Open AccessArticle

Preparation of Hollow Silica Nanoparticles with Polyacrylic Acid and Their Moisture Sorption Properties

by Quanyue Wen, Kento Ishii and Masayoshi Fuji

Coatings 2024, 14(7), 829; https://doi.org/10.3390/coatings14070829 - 3 Jul 2024

Viewed by 1209

Abstract

Hollow silica nanoparticles (HSNPs) have hygroscopic properties because of their high specific surface area and surface hydroxyl groups. However, compared with other hygroscopic materials, their hygroscopic properties are relatively weak, which limits the further application of HSNPs. One feasible method to enhance their hygroscopic properties is by combining highly hygroscopic materials with hollow silica nanoparticles. To take advantage of the high hygroscopicity of polyacrylic acid (PAA) when combined with the high specific surface area of the hollow particles, PAA was coated on the inner and outer surfaces of the silica shell of the nanoparticles in this study to prepare hollow nanoparticles with a PAA/silica/PAA multilayer structure. The size of the PAA/silica/PAA multi-layer nanoparticles is about 85 nm, and the shell thickness is 25 nm. The specific surface area of the multi-layer nanoparticles is 58 m²/g. The water vapor adsorption capacity of multi-layer structure hollow nanoparticles was increased by 160% compared with the HSNPs (increased from 45.9 cm³/m² to 109.1 cm³/m²). Meanwhile, at the same content of PAA, the PAA/silica/PAA-structured particles will adsorb 9% more water vapor than the PAA/silica-structured particles. This indicates that the high specific surface area structure of the hollow particles will enhance the adsorption ability of PAA toward water vapor. This novel structure of PAA-HSNPs is expected to be used as a humidity-regulating material for filler in environmental and architectural applications. Full article

(This article belongs to the Special Issue New Developments of Protective Coatings, Organic Polymers, and Surface Analysis: 2nd Edition)

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26 pages, 6727 KiB

Open AccessArticle

Anticorrosion Protection of New Composite Coating for Cobalt-Based Alloy in Hydrochloric Acid Solution Obtained by Electrodeposition Methods

by Florina Branzoi, Alexandru Marius Mihai and Mohamed Yassine Zaki

Coatings 2024, 14(1), 106; https://doi.org/10.3390/coatings14010106 - 12 Jan 2024

Viewed by 1354

Abstract

In this work, electrochemical deposition techniques (galvanostatic and potentiostatic) were used to obtain coatings of a new composite polymer, 3-methylpyrrole—sodium dodecyl sulfate/poly 2-methythiophene (P3MPY-SDS/P2MT), on cobalt-based alloy samples for anti-corrosion safety. The use of sodium dodecyl sulfate as a dopant ion in electrosynthesis can have a relevant effect on the anticorrosive property of the composite polymer layer by blocking the entry of corrosive ions. The cobalt alloy specimen had an important impact on the electrochemical performance of the composite coating and this together with the presence of the polymeric layer was achieved by simultaneously constitution of a complex oxides film and polymeric layers. The polymeric coatings were analyzed using scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and cyclic voltammetry (CV) methods. The corrosion protection of the P3MPY-SDS/P2MT-covered cobalt-based alloy was explored using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization procedures in a 1 M HCl solution. The corrosion speed of the P3MPY-SDS/P2MT-covered cobalt-based alloy was observed to be ~10 times less than an uncovered specimen, and the effectiveness of the composite layers of this coating is greater than 91%. This superior efficaciousness was obtained by the electropolymerization of P3MPY-SDS/P2MT at current densities of 1 mA/cm² and 0.5 mA/cm², applied potentials of 0.9 V and 1.0 V, and a molar ratio of 5:1. Corrosion test results indicate that the P3MPY-SDS/P2MT coatings provide a good result: protection against the corrosion of a cobalt-based alloy in aggressive solutions. Full article

(This article belongs to the Special Issue New Developments of Protective Coatings, Organic Polymers, and Surface Analysis: 2nd Edition)

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30 pages, 7307 KiB

Open AccessEditor’s ChoiceArticle

Preparation and Testing of Anti-Corrosion Properties of New Pigments Containing Structural Units of Melamine and Magnesium Cations (Mg²⁺)

by Miroslav Kohl, Fouzy Alafid, Karolína Boštíková, Anna Krejčová, Stanislav Slang, Dominik Řezníček, Radim Hrdina and Andréa Kalendová

Coatings 2023, 13(11), 1968; https://doi.org/10.3390/coatings13111968 - 19 Nov 2023

Cited by 1 | Viewed by 1718

Abstract

This paper deals with the properties and testing of newly prepared organic pigments based on melamine cyanurate containing magnesium or zinc cations depending on their composition and anticorrosive properties in model coatings. Organic pigments based on melamine cyanurate with Mg²⁺ in the form of a complex differing in the ratio of melamine and cyanurate units were prepared. Furthermore, a pigment based on melamine citrate with magnesium cation Mg²⁺, a pigment based on melamine citrate with magnesium cation, and a pigment based on melamine cyanurate with zinc cation were prepared. The properties of Mg-containing organic pigments were also compared with those of selected magnesium-containing inorganic oxide-type pigments. The above-synthesized pigments were characterized by inductively coupled plasma-optical emission spectroscopy, elemental analysis, scanning electron microscopy, and X-ray diffraction. In addition, the basic parameters that are indicative of the applicability of the pigments in the binders of anti-corrosion coatings were determined. The anti-corrosive properties of the tested pigments were verified after application to the epoxy-ester resin-based paint binder in three different concentrations: at pigment volume concentrations of 0.10%, 0.25%, and 0.50%. The anticorrosive effectiveness of pigmented organic coatings was verified by cyclic corrosion tests in a salt electrolyte fog (NaCl + (NH₄)₂SO₄) in an atmosphere containing SO₂ and by the electrochemical technique of linear polarization. Finally, the effect of the structure of the pigments on the mechanical resistance of the organic coatings was investigated. The results obtained showed that the new organic pigments exhibit anticorrosive properties, and at the same time, differences in performance were found depending on the structure of the pigments tested. Specifically, the results of cyclic corrosion tests and the electrochemical technique of linear polarization clearly demonstrated that synthesized pigments of the organic type based on melamine cyanurate containing magnesium or zinc cations ensure the anti-corrosion efficiency of the tested organic coatings. The highest anti-corrosion efficiency was achieved by the system pigmented with synthesized melamine cyanurate with magnesium cation (C₁₂H₁₆MgN₁₈O₆), whose anti-corrosion efficiency was comparable to the anti-corrosion efficiency of the tested inorganic pigment MgFe₂O₄, which was prepared by high-temperature solid-phase synthesis. In addition, these organic coatings achieved high mechanical resistance after being tested using the most used standardized mechanical tests. Full article

(This article belongs to the Special Issue New Developments of Protective Coatings, Organic Polymers, and Surface Analysis: 2nd Edition)

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19 pages, 4541 KiB

Open AccessEditor’s ChoiceArticle

Composite of Poly(Vinyl Chloride) Plastisol and Wood Flour as a Potential Coating Material

by Przemysław Siekierka, Edwin Makarewicz, Sławomir Wilczewski, Krzysztof Lewandowski, Katarzyna Skórczewska, Jacek Mirowski and Magdalena Osial

Coatings 2023, 13(11), 1892; https://doi.org/10.3390/coatings13111892 - 3 Nov 2023

Cited by 2 | Viewed by 1635

Abstract

This paper presents the results of a study of the properties of a new composite material made from poly(vinyl chloride) plastisol (PVC) and conifer-derived wood flour. The material can be used for thermal insulation, floor coverings with high resistance to mechanical trauma, and protective coatings. The plastisol was made from emulsion poly(vinyl chloride), the plasticiser was bis(2-ethylhexyl) adipate, and the stabiliser was octyltin mercapeptide. Two types of flour were used: fine-grained and coarse-grained. Its properties, such as bulk density, oil number, and plasticiser number, were determined. The polymer-wood composite contained 20 or 30 wt.% wood flour in PVC. Plastisol was obtained by repeated mixing, mashing, and venting under vacuum. The produced composite material was gelated at temperatures of 130, 150, and 170 °C. The gelation process of the composites was studied in a Brabender apparatus. Samples in the form of polymer films were used to study density, hardness, thermal stability, and mechanical and thermomechanical properties. The structure of the composites was observed by scanning electron microscopy (SEM). A summary of all test results showed that composite films made from PVC plastisol with 20 wt.% of fine wood flour gelled at 150 °C had the most favourable physical, mechanical, and thermal properties. Full article

(This article belongs to the Special Issue New Developments of Protective Coatings, Organic Polymers, and Surface Analysis: 2nd Edition)

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16 pages, 17298 KiB

Open AccessEditor’s ChoiceArticle

Epoxy Coatings Doped with (3-Aminopropyl)triethoxysilane-Modified Silica Nanoparticles for Anti-Corrosion Protection of Zinc

by Tamara-Rita Ovari, Timea Toth, Gabriel Katona, Gabriella Stefánia Szabó and Liana Maria Muresan

Coatings 2023, 13(11), 1844; https://doi.org/10.3390/coatings13111844 - 27 Oct 2023

Cited by 2 | Viewed by 3280

Abstract

Epoxy (EP) coatings containing silica (SiO₂) and (3-Aminopropyl)triethoxysilane-modified silica (SiO₂-APTES) nanoparticles were prepared via the dip-coating technique on a zinc substrate. A detailed study was performed regarding their incorporation into the matrix, followed by the investigation of the newly obtained organic–inorganic hybrid coatings’ anti-corrosive properties. The two methods of embedding the nanoparticles were (I) modification of the silica nanoparticles with APTES followed by their introduction into the epoxy resin, and (II) functionalization of the silica nanoparticles in the epoxy gel before the addition of the hardener. It was observed that through the second method, the coating was homogeneous, with no sign of agglomerates. The nanoparticles were subjected to morpho-structural and physical–chemical analysis using Fourier-Transform Infrared Spectroscopy and Transmission Electron Microscopy, while the coatings were examined through Scanning Electron Microscopy and Energy-Dispersive X-Ray Spectroscopy, contact angle measurements and adhesion tests. The anti-corrosive performance of epoxy-coated zinc was analyzed using electrochemical impedance spectroscopy and polarization curves to investigate the impact of silanized SiO₂ nanoparticle incorporation. Based on long-term corrosion testing, the epoxy-SiO₂-APTES composite coatings showed a higher corrosion resistance than the undoped epoxy layer. Full article

(This article belongs to the Special Issue New Developments of Protective Coatings, Organic Polymers, and Surface Analysis: 2nd Edition)

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21 pages, 7189 KiB

Open AccessEditor’s ChoiceArticle

Sustainable Integration of Zinc Oxide Nanoparticles: Enhancing Properties of Poly(ε-Caprolactone) Electrospun Nanofibers and Cast Films

by Johar Amin Ahmed Abdullah, José J. Benítez, Antonio Guerrero and Alberto Romero

Coatings 2023, 13(10), 1665; https://doi.org/10.3390/coatings13101665 - 22 Sep 2023

Cited by 5 | Viewed by 2365

Abstract

This study investigated the impact of adding zinc oxide nanoparticles (ZnO-NPs) to electrospun membranes and cast films made of poly(ε-caprolactone) (PCL). The physicochemical, mechanical, and morphological properties of the samples were analyzed. Physicochemical parameters included water contact angle (WCA), water vapor transmission rate (WVTR), permeance, water vapor permeability (WVP), light transmission (T₆₀₀), and transparency (T). Mechanical properties, such as maximum stress (Ϭ_max), elongation (ε_max), and Young’s modulus (MPa), were also evaluated. Morphological properties were analyzed in terms of thickness, dispersion, and surface roughness (measured by the arithmetic (Ra) and quadratic (Rq) averages). The crystallinity and melting point, as well as the functional DPPH^• scavenging percentage (SP%), were also studied. The results showed that adding 1 wt% ZnO-NPs improved the water barrier properties of PCL membranes and films, increasing WCA by 1%–6% and decreasing WVTR by 11%–19%, permeance by 34%–20%, and WVP by 4%–11%, respectively. The T₆₀₀ values of PCL/ZnO-NPs membranes and films were 2–3 times lower than those of neat PCL samples, indicating improved optical properties. The mechanical properties of the composite membranes and films also improved, with Ϭ_max increasing by 56%–32% and Young’s modulus increasing by 91%–95%, while ε_max decreased by 79%–57%. The incorporation of ZnO-NPs also increased the thickness and surface roughness of the samples. The SP% of PCL/ZnO-NPs increased by almost 69%, demonstrating the beneficial effects of ZnO-NPs on the system. These findings suggest that incorporating ZnO-NPs into PCL membranes and films can enhance their properties, making them well suited for various applications, such as those within the realm of materials science and nanotechnology. Full article

(This article belongs to the Special Issue New Developments of Protective Coatings, Organic Polymers, and Surface Analysis: 2nd Edition)

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36 pages, 6604 KiB

Open AccessArticle

New Azo Dyes-Based Mg Complex Pigments for Optimizing the Anti-Corrosion Efficiency of Zinc-Pigmented Epoxy Ester Organic Coatings

by Miroslav Kohl, Fouzy Alafid, Karolína Boštíková, Marek Bouška, Anna Krejčová, Jan Svoboda, Stanislav Slang, Ludmila Michalíčková, Andréa Kalendová, Radim Hrdina, Ladislav Burgert, Eva Schmidová, Pravin P. Deshpande and Abhijit A. Bhopale

Coatings 2023, 13(7), 1276; https://doi.org/10.3390/coatings13071276 - 20 Jul 2023

Cited by 7 | Viewed by 2543

Abstract

This work addresses the possibilities of using synthesized novel magnesium complex dyes in zinc pigmented organic coatings based on epoxyester resin to reduce the zinc content in these coatings while maintaining or increasing the anticorrosive efficiency of them. The magnesium complexes Mg-Dye-I (C₃₄H₂₆MgN₈O₆), Mg-Dye-II (C₂₆H₁₉MgN₃O₅), Mg-Dye-III (C₁₇H₁₀MgN₂O₃), and Mg-Dye-IV (C₂₅H₁₈MgN₄O₆) with a series of azo carboxylate ligands were prepared from the diazo-coupling reaction of anthranilic acid with 5-methyl-2-phenyl-3-pyrazolone (Dye I; C₁₇H₁₄N₄O₃), anthranilic acid with naphthol AS-PH (Dye II; C₂₆H₂₁N₃O₅), anthranilic acid with 2-naphthol (Dye III; C₁₇H₁₂N₂O₃), and 2-amino-5-nitrophenol with naphthol AS-PH (Dye IV; C₂₅H₂₀N₄O₆). The synthesized novel magnesium complex dyes were characterized by analytical methods. Model coatings containing these dyes at pigment volume concentrations (PVCs) = 1, 3, 5 and 10% and zinc at a ratio of pigment volume concentration/critical pigment volume concentration (PVC/CPVC) = 0.60 were formulated to study the inhibitory properties of the individual synthesized magnesium complex dyes. Model coatings containing inorganic pigments (MgO and Ca-Mg-HPO₄) at PVCs = 1%, 3%, 5% and 10% and zinc at PVC/CPVC = 0.60 were also formulated. The coating pigmented only by zinc at PVC/CPVC = 0.60 was prepared as a standard organic coating. Corrosion resistance was also evaluated by potentiodynamic polarization studies and electrochemical impedance spectroscopy. The properties of organic coatings were also tested using other standardized and derived corrosion tests. In addition, the mechanical properties of the studied organic coatings were determined using standard tests. The aim of the work was to verify the possible synergistic efficiency of novel magnesium complex dyes by improving the mechanical, anti-corrosion, and chemical properties of zinc pigmented organic coatings. Full article

(This article belongs to the Special Issue New Developments of Protective Coatings, Organic Polymers, and Surface Analysis: 2nd Edition)

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Review

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16 pages, 1747 KiB

Open AccessReview

A Comprehensive Outlook of Scope within Exterior Automotive Plastic Substrates and Its Coatings

by Jomin Thomas, Renuka Subhash Patil, Jacob John and Mahesh Patil

Coatings 2023, 13(9), 1569; https://doi.org/10.3390/coatings13091569 - 7 Sep 2023

Cited by 21 | Viewed by 3976

Abstract

Among non-metal substrate coatings, plastic substrates have certainly asserted themselves as a key market, especially in the automotive industry. The substrates within exterior automotive industries are being diversified and commercialized at a rapid pace. Mainly attributed to the emergence of electric vehicles, environmental regulations, and functional requirements, there is huge scope and many opportunities for advancements and groundbreaking technologies. The above factors have led to the dawn of new and improved coating materials within the revolutionizing new substrate market. At the same time, new product innovations within ultraviolet (UV)-curable technologies, powder coating, nanotechnologies, and several other platforms have brought the possibility of novel coating systems into the picture. This review outlines the inherent challenges, the progress made thus far, and the future opportunities of two significant exterior plastic substrates: thermoplastic polyolefin (TPO) and polycarbonate (PC). While the former serves as the historical choice for plastic bumpers across the globe, the latter has captured the most research attention in recent times as a lightweight option against glass coatings. A meticulous overview of the existing literature was conducted to summarize the recent approaches with a few critical analyses. To surpass the challenges to the equivalent performances, a few of the most promising research studies were also examined, including the sustainability aspect. Full article

(This article belongs to the Special Issue New Developments of Protective Coatings, Organic Polymers, and Surface Analysis: 2nd Edition)

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