Multi-functional low-cost epoxy based nanocomposite coatings
Pranav Nawani
“An ounce of prevention is worth a pound of cure.”? Benjamin Franklin Corrosion is a significant global issue, resulting in high maintenance and repair costs. Long term structural integrity of metal and its products is directly dependent on its anti-corrosive properties. Surfaces exposed to marine environments are prone to microbial attachment followed by biofilm formation, resulting in bio-fouling. Hence coatings are used to protect the surfaces against corrosion and biofilm formation. Currently various organic coatings are used to protect metals and their cost is directly dependent upon the cost of fillers used to impart specific properties. Conventionally expensive Zinc, Titanium and Silver based compounds are used in coatings for corrosion and/or microbial protection of surfaces. Underlying issue of using these compounds as fillers is that they effect mechanical and barrier properties adversely, hence either they are used as a base coat or additional fillers are used to compensate for such property losses. Most of these coatings need an enhanced anti-microbial surface and improvement in their barrier efficacy against water/moisture, oxygen, and chloride ions. Hence it is imperative to develop low-cost fillers that will enhance both active & passive corrosion resistance properties, prevent microbial attachment on the surfaces and will not degrade any polymeric properties. ASL is developing a multi-functional low cost epoxy-clay nanocomposite coating, for microbial and corrosion resistance. Multi-functional coatings are developed using a multi-component approach, where the innovation lays in deriving the benefits of various fillers through a combinatorial approach to synergistic harvesting of functionality and vigor. The primary filler is a naturally abundant clay material and owing to their sheet like morphology and layered structures, their surface can be modified to achieve the desired property enhancements. Sheet like morphology enhances polymer filler interactions, resulting in enhanced mechanical and barrier properties. Clay based fillers are easily adaptable to current paint and coating manufacturing protocols, making them commercially viable. Potential applications of such fillers is in epoxy based coatings and/or paints used in: 1) Marine applications. 2) Defense and infrastructure. 3) Others; Hospitals, laboratories, medical devices and food packaging containers. Dispersion of uniquely modified clay based fillers in the epoxy matrix results in a superior coating, with a combination of improved anti-corrosive, anti-microbial, mechanical, and reduced barrier properties. Sheet like structure of clay provides enhanced barrier properties, passive protection and transition ion modification of the clay surface provides active protection against corrosion and biofilm formation. Through a multi-component approach that includes transition metal ion modified clays as primary fillers the investigation is driven toward development and usage of low cost and environmentally friendly materials. Low-cost clay based fillers can be used in paints and coatings for enhancing barrier efficacy, corrosion and anti-microbial resistance to significantly improve protection of the coated surface and replace conventional expensive Zinc fillers.