Organic–Inorganic Hybrid Sol–Gel Materials for Corrosion Mitigation

A special issue of Coatings (ISSN 2079-6412).

Deadline for manuscript submissions: closed (15 January 2022) | Viewed by 9227

Special Issue Editor


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Guest Editor
Centro de Química, Campus de Gualtar, Universidade do Minho, 4710-057 Braga, Portugal
Interests: sol–gel; materials; corrosion; coatings; materials for sensing applications
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Special Issue Information

Dear Colleagues,

We would like to invite you to submit your work to this Special Issue on “Organic–Inorganic Hybrid Sol–Gel Materials for Corrosion Mitigation”. The wide application range of organic–inorganic hybrid (OIH) materials has attracted significant attention over the past decades. The combination of inorganic materials and organic polymers in a single phase allows one to tailor the electrical, optical, and mechanical properties for numerous applications. This unrestricted design concept has led to the development of multifunctional coatings for several applications, such as mitigation of mechanical abrasion, erosion, and corrosion. OIH materials can be easily obtained using the sol–gel method under mild synthesis conditions. Furthermore, the large variety of available chemical precursors allows a wide range of coatings to be produced with tuned physicochemical properties. Currently, the development of OIH sol–gel materials is focused on green, safe, smart, and economic approaches. Ideally, these OIH sol–gel materials should be smart with the ability to act according to certain needs, i.e., be stimuli-responsive in a defined environment.

The aim of this Special Issue is to present the latest experimental and theoretical developments in this field, combining original research papers and review articles from leading groups worldwide.

In particular, the topics of interest include, but are not limited to:

  • OIH sol–gel coatings for corrosion mitigation of metallic alloys;
  • Sol–gel materials for corrosion mitigation of metallic devices for energy and environmental applications;
  • Hybrid sol–gel nanostructured materials for smart coatings;
  • Multifunctional OIH sol–gel coatings for corrosion protection including self-healing, anti-fouling, and superhydrophobic functions.

Dr. Rita Bacelar Figueira
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • corrosion
  • sol–gel
  • multifunctional materials
  • superhydrophobic
  • self-healing
  • anti-fouling

Published Papers (3 papers)

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Research

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16 pages, 5978 KiB  
Article
Vapour Phase Deposition of Thin Siloxane Coatings on the Iron Surface. The Impact of the Layer Structure and Oxygen Adsorption on Corrosion Stability
by Andrei Nazarov, Maxim Petrunin, Liudmila Maksaeva, Tatyana Yurasova, Pierluigi Traverso and Andrey Marshakov
Coatings 2021, 11(10), 1217; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11101217 - 04 Oct 2021
Cited by 2 | Viewed by 2092
Abstract
The mechanism of iron corrosion protection by thin siloxane films was clarified. Quartz crystal microbalance technique (QCM) was applied to control the vapour phase deposition of alkoxysilanes and the formation of thin siloxane films. It was shown that the addition of water vapour [...] Read more.
The mechanism of iron corrosion protection by thin siloxane films was clarified. Quartz crystal microbalance technique (QCM) was applied to control the vapour phase deposition of alkoxysilanes and the formation of thin siloxane films. It was shown that the addition of water vapour increased the thickness of the grafted siloxane films. Crystal-like films spontaneously grow to 10–16 monolayers at 100% RH of Ar flow due to the catalytic effect of the surface. X-ray photoelectron (XPS) and Auger spectroscopies analysed the thin siloxane films and Scanning Kelvin Probe (SKP) showed the formation of iron-siloxane bonds passivating the iron surface. The films showed high hydrophobicity and corrosion inhibition in humid air contaminated by sulphur dioxide. Thick films were less ordered, hydrophilic and accelerated the corrosion of iron. For corrosion protection, the presence of oxygen in the atmosphere is extremely important. In a wet Ar atmosphere, contaminated by sulphur dioxide, the surfaces are not stable and quickly corroded. Oxygen adsorption stabilizes the surface oxide film that correspondingly preserves the anchoring iron-siloxane bonds and enables corrosion protection by the coating. Full article
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18 pages, 3990 KiB  
Article
Interplay of Hydrophobic Thiol and Polar Epoxy Silicate Groups on Microstructural Development in Low-Alcohol, Crosslinked Sol–Gel Coatings for Corrosion Prevention
by Shegufa Shetranjiwalla, Andrew J. Vreugdenhil and Oliver Strong
Coatings 2021, 11(3), 306; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11030306 - 08 Mar 2021
Cited by 5 | Viewed by 2588
Abstract
We have demonstrated that our patented, crosslinked, sol–gel, epoxy–thiol silicates made from the combination of (a) tetraethoxysilane (TEOS, T), 3-glycidoxypropyltrimethoxysilane (GPTMS, G), and the (b) sulfur-containing 3-mercaptopropyltrimethoxysilane (MPTMS, S) with TEOS in a 1:1 stoichiometric ratio form the 1:1 TGST [...] Read more.
We have demonstrated that our patented, crosslinked, sol–gel, epoxy–thiol silicates made from the combination of (a) tetraethoxysilane (TEOS, T), 3-glycidoxypropyltrimethoxysilane (GPTMS, G), and the (b) sulfur-containing 3-mercaptopropyltrimethoxysilane (MPTMS, S) with TEOS in a 1:1 stoichiometric ratio form the 1:1 TGST (crosslinked epoxy and thiol silicates) coating, which can be successfully utilized for the corrosion protection of low-carbon steel. Alcohols that are a by-product of sol–gel reactions influence the network formation, crosslinking density, and formulation stability, are volatile organic contents, and are regulated in the coatings industry. To improve environmental sustainability, a series of low-alcohol (LA) formulations with TG:ST ratios of 3:1 to 1:3 was prepared to investigate the microstructural development and crosslinking reactions emerging from the interplay of the hydrophobic thiol and polar epoxy silicates induced by the low-alcohol environment. The impact on crosslinking density was characterized by Fourier Transform Infrared (FTIR), Raman, XPS, viscosity, and pot-life measurements. Low-alcohol TGST (LA(TGST)) formulations were compared, using the example of 1:1 TGST, to corresponding TGST formulations where alcohols were retained. The reduced impact of LA(TGST) formulations on global warming was quantified. The glossy and scratch-resistant LA(TGST) coatings showed 71% enhanced corrosion protection compared to the non-crosslinked hybrids. Full article
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Review

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26 pages, 47156 KiB  
Review
Sol-Gel Coating Membranes for Optical Fiber Sensors for Concrete Structures Monitoring
by Bárbara R. Gomes, Rui Araújo, Tatiana Sousa and Rita B. Figueira
Coatings 2021, 11(10), 1245; https://0-doi-org.brum.beds.ac.uk/10.3390/coatings11101245 - 13 Oct 2021
Cited by 5 | Viewed by 3523
Abstract
The use of advanced sensing devices for concrete and reinforced concrete structures (RCS) is considered a rational approach for the assessment of repair options and scheduling of inspection and maintenance strategies. The immediate benefits are cost reduction and a reliable prevention of unpredictable [...] Read more.
The use of advanced sensing devices for concrete and reinforced concrete structures (RCS) is considered a rational approach for the assessment of repair options and scheduling of inspection and maintenance strategies. The immediate benefits are cost reduction and a reliable prevention of unpredictable events. The use of optical fiber sensors (OFS) for such purposes has increased considerably in the last few years due to their intrinsic advantages. In most of the OFS, the chemical transducer consists of immobilized chemical reagents placed in the sensing region of the optical sensor by direct deposition or by encapsulation in a polymeric matrix. The choice of the support matrix impacts directly on the performance of the OFS. In the last two decades, the development of OFS functionalized with organic–inorganic hybrid (OIH) sol–gel membranes have been reported. Sol–gel route is considered a simple method that offers several advantages when compared to traditional synthesis processes, allowing to obtain versatile materials with unique chemical and physical properties, and is particularly valuable in the design of OIH materials. This review will provide an update of the current state-of-the-art of the OFS based on OIH sol-gel materials for concrete and RCS since 2016 until mid-2021. The main achievements in the synthesis of OIH membranes for deposition on OFS will be discussed. The challenges and future directions in this field will also be considered, as well as the main limitations of OFS for RCS monitoring. Full article
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