Cardanol and Its Derivatives: Innovations in Waterborne Coating Technologies

Utilization of bio-renewable materials to replace petroleum-based building blocks for advanced coatings has been a major focus area for researchers in the development of eco-friendly and sustainable products. Additionally, the growing restrictions on volatile organic compounds and hazardous air pollutants have forced industries to opt for waterborne systems. Therefore, considerable focus has been directed toward bio-based waterborne systems. Over the years, bio-based waterborne systems have evolved and been established with superior advantages such as fast curing, chemical resistance, excellent adhesion, and enhanced performance. Various biomaterials have been explored in the past for waterborne systems such as vegetable oils, lignin, tannin, cellulose, sugar alcohols, cashew nutshell liquid, and others. Among them, cardanol, an agricultural non-edible byproduct of cashew nut industry, has emerged as a promising candidate for waterborne systems due to its unique structural characteristics, abundant availability, low cost, inedibility, and biodegradability. Owing to its phenolic nature and presence of unsaturated alkyl chain at meta position, cardanol provides excellent balance of hardness and flexibility along with superior corrosion resistance. This review highlights recent advancements in cardanol-based waterborne systems as well as its application in surface coatings. In addition, many research groups have modified cardanol and its derivatives through variety of chemistries such as polyurethane dispersions, epoxy curing agents, and acrylic latexes for waterborne systems, which is also summarized in this review. Studies revealed that these coatings exhibited excellent performance properties offering tranquillity to the concern regarding the inferiority of cardanol-based waterborne coatings.