UV-Initiated the Ultra-Fast Curing: An Amazing Breakthrough of Frontal Polymerization in Hydrogel Coatings

Significance 

Hydrogel is a kind of gel material with organic polymer as the skeleton structure and water as the dispersing medium. The hydrogel coatings on the surface of the material can make the system have the strength and hardness of the base, hydrogel hydrophilicity, self-lubrication, biocompatibility, and controllable drug-loading functions. ‘Self-propagating’ hydrogels, broaden the field of application once the hydrogel starts forming or coating a surface, and the process continues automatically across the surface or structure without needing additional external input. Another important characteristic is being bubble-free because certain applications, especially uniformity and clarity of the coating are important. Bubbles in hydrogels or coatings can create weak spots and affect the performance of the material. A bubble-free coating implies a smooth, consistent layer without air pockets, which can be important for optical clarity or mechanical integrity. Bubble-free, self-propagating hydrogel coatings have significant potential in the field of corrosion protection due to their unique properties. For instance, hydrogels can act as a physical barrier between the metal surface and corrosive elements like water, oxygen, and salts. The ability of hydrogels to form a continuous, uniform coating ensures that there are no gaps or weak points where corrosion could initiate. Additionally, hydrogels can be engineered to incorporate corrosion inhibitors, which can be slowly released over time. This controlled release can provide long-term protection against corrosion, especially in harsh environments. The hydrogel matrix ensures that the inhibitors are distributed evenly across the coated surface. Moreover, some hydrogels have the ability to self-heal after being damaged, which is highly beneficial for corrosion protection. If the coating is scratched or otherwise compromised, the hydrogel can re-form the damaged area, thus maintaining an uninterrupted protective layer. Furthermore, by acting as a barrier, hydrogels can reduce the electrochemical reactions that lead to corrosion. They can limit the access of electrolytes to the metal surface, thus slowing down or preventing the corrosion process. Unlike some traditional corrosion inhibitors and coatings, hydrogels can be formulated to be non-toxic and environmentally benign, which is increasingly important in many industries. The self-propagating nature of these coatings makes the application process more efficient and uniform, which is particularly advantageous for large structures or complex geometries where manual coating application would be challenging and time-consuming.

In a new study published in ACS Applied Materials & Interfaces led by Professor Guofu Qiao and conducted by PhD candidates Jiongfeng Sun Peng Han and Dr. Li Zhou from Harbin Institute of Technology, the researchers reported an innovative approach to create hydrogel anticorrosive coatings, they developed a method to rapidly synthesize bubble-free, self-propagating hydrogels using UV-initiated frontal polymerization. This method involved the use of nano-SiO2 to form dense hydrogen bonds, enhancing the stability of the hydrogel’s three-dimensional network. The process was carefully designed to ensure the creation of hydrogels without bubbles and to keep the reaction temperature below the boiling point of solutions. To validate their findings, the team employed various advanced analytical techniques, including Scanning Electron Microscopy (SEM) which provided detailed images of the hydrogel surface, showing uniformity and bubble-free morphology., Atomic Force Microscopy (AFM) which offered insights into the surface roughness and topography of the coatings, indicating a smooth and consistent texture., Fourier Transform Infrared (FTIR) Spectroscopy which identified the specific chemical bonds and functional groups within the hydrogel, confirming the successful polymerization and chemical structure, Electrochemical Impedance Spectroscopy (EIS) which measured the hydrogel’s anticorrosive properties, particularly its effectiveness in impedance and resistance to corrosion, Ion Chromatography (IC) which analyzed the presence and concentration of ions, particularly chloride ions, to assess the coating’s ability to block corrosive agents., X-ray Photoelectron Spectroscopy (XPS) which provided elemental composition details of the hydrogel surface, confirming the presence of key elements involved in the polymerization process and ultra-depth-of-field microscopy which enabled a three-dimensional view of the coating, further confirming the uniformity and integrity of the hydrogel layer. These results collectively highlighted the hydrogel’s effectiveness in corrosion resistance and its potential for industrial applications in harsh environments.

In conclusion, the new study by Professor Guofu Qiao and his team marks a significant advancement in the field of anticorrosive coatings. The synthesized hydrogel coatings demonstrated exceptional capabilities in physically blocking corrosive media, thereby protecting steel surfaces effectively. 1,2,4-triazole could accumulate on the steel surface so that the active anti-corrosion function takes effect. The research’s implications extend beyond its immediate findings. It opens new avenues for in-situ synthesis of hydrogel anticorrosive coatings on mild steel surfaces, even under wet or underwater conditions. This development has the potential to revolutionize the way we protect metal surfaces in marine and other corrosive environments and could be particularly useful in industries like maritime, infrastructure, automotive, and aerospace, where corrosion is a major concern and can lead to significant maintenance costs and safety issues. Moreover, the research is of great significance in the fields of ultra-fast waterproofing and plugging, crack repair, 3-D printing and ultra-rapid prototyping, etc.

UV-Initiated the Ultra-Fast Curing: An Amazing Breakthrough of Frontal Polymerization in Hydrogel Coatings - Advances in Engineering

About the author

Jiongfeng Sun is currently a PhD candidate in Civil Engineering at Harbin Institute of Technology, China. He received his master’s degree in Civil Engineering from Harbin Institute of Technology in 2021. His research interests include self-sensing composites, frontal polymerization, novel material, and numerical methods. Till now, his work has been reported by ACS Applied Material & Interfaces, Structural Health Monitoring-An International Journal, etc.

About the author

Li Zhou currently holds a senior engineer position at Harbin Institute of Technology. She received her Ph.D. degree at Dalian University of Technology in 2009. She was a postdoctoral research associate at Nagoya University in 2009-2010. Her research interests focus on organometallic compounds catalyzed construction of C-C and C-N chemical bonds and photocatalytic water splitting.

About the author

Peng Han is a PhD student of School of Civil Engineering in Harbin Institute of Technology. The objectives of his research are (i) to model the thermodynamic model of cement hydration under the corrosion environment; (ii) to quantify the mass transfer process of RC materials subjected to stray current; (iii) to explore the coupling mechanism of corrosion and fatigue damage to RC materials.

About the author

Guofu Qiao is a professor at Harbin Institute of Technology. His research interests focus on the utilization of extraterrestrial resources and base construction, material corrosion and protection, smart materials and structures, structural monitoring and control, and green building and building industrialization. He has presided over more than 20 national, provincial, and local research projects, published nearly 100 academic papers, authorized more than 30 national invention patents and software copyrights, and published one monograph. Some of his research work has won the Heilongjiang Province Technological Invention Award, the Jilin Province Scientific and Technological Progress Award, and the National Prize for Technological Invention.

Reference

Jiongfeng Sun, Li Zhou, Peng Han, and Guofu Qiao*. UV-Initiated Frontal Polymerization for the Fast Synthesis of Bubble-Free, Self-Propagating Hydrogel Anticorrosive Coatings. ACS Appl. Mater. Interfaces 2023, 15, 28618−28625.

Go to ACS Appl. Mater. Interfaces

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