Spray-On Polymer-Clay Multilayers as a Superior Anticorrosion Metal Pretreatment

Abstract

Pretreatment coatings applied to metals are essential in the overall performance of anticorrosion coating systems. Hexavalent chromium, a widely used pretreatment for aluminum is now considered harmful. Therefore, a need for environment‐friendly yet efficient and scalable pretreatment coatings has emerged. Here, the authors present the spray‐assisted layer‐by‐layer (LbL) assembly and anticorrosion performance of a highly ordered polymer–clay nanocomposite coating. This approach is an entirely water‐based process, allowing for application over large surface areas. This novel pretreatment coating (25 wt% clay) presents a brick‐and‐mortar multilayered structure, where the montmorillonite clay (MMT) acts as a physical oxygen barrier, while preventing the dissolution of corrosion products—thus delaying corrosion. The branched polyethylenimine polymer (BPEI) mortar provides surface buffering once the corrosion process initiates. The anticorrosion properties of the LbL coating are evaluated using electrochemical measurements and salt‐spray testing. This BPEI/MMT system presents good anticorrosion properties, making it a potential alternative pretreatment.

Fourier transform infrared spectroscopy investigation of water microenvironments in polyelectrolyte multilayers at varying temperatures

“…Self-healing properties of PEMs have been tapped into for use as protective coatings over corrosion effects or fire propagation. 3,4 Polymer-clay coatings made from branched polyethylenimine (BPEI) and montmorillonite (MMT) were demonstrated to have long-term environmentally-friendly anti-corrosion properties when used as pre-treatment for aluminum alloy. 4 In another work, the same BPEI/MMT PEM has exhibited fire-retardation properties by of selfhealing.…”

“…3,4 Polymer-clay coatings made from branched polyethylenimine (BPEI) and montmorillonite (MMT) were demonstrated to have long-term environmentally-friendly anti-corrosion properties when used as pre-treatment for aluminum alloy. 4 In another work, the same BPEI/MMT PEM has exhibited fire-retardation properties by of selfhealing. 48 Interest in PEMs in medicine and pharmaceuticals is also on the rise.…”

“…By virtue of their behavioral flexibility, PECs and PEMs have been studied for applications in a wide range of fields. From potential applications involving their use as separators in batteries 2 to protective coatings [3][4][5] to stimuli-responsive drug delivery and bio-compatible coatings 6,7 , PECs and PEMs are worth the amount of attention they've received over the past years.…”

Relaxation Times of Solid-like Polyelectrolyte Complexes of Varying pH and Water Content

“…Aqueous solutions of oppositely charged polyelectrolytes (PEs) phase separate upon mixing, leading to the formation of a dilute supernatant and a polymer-rich phase known as a polyelectrolyte complex (PEC). PECs are formed due to electrostatic attractions between oppositely charged PEs and the entropic release of counterions and water. − PECs can exist as solid-like complexes or liquid-like coacervates, − and the physical properties are affected by salt, temperature, water, pH, and hydrophobicity of the PEs. − This leads to applications of PECs in drug delivery systems, humidity sensors, separation membranes, electrochemistry, and many more. − However, there is little information regarding the impact of complexation pH and water content on the mechanical properties and relaxation of PECs.…”

UV-protection from chitosan derivatized lignin multilayer thin film

“…While the relatively high number of processing steps can appear daunting, the scalability of LbL deposition has been demonstrated numerous times for both roll-to-roll immersion and spraybased processing. [52][53][54] As further applications for lignin-based LbL lms are developed, this scalability will be critical to ensure commercial relevance of this technology.…”