Nature-Inspired Synthesis of Fully Bio-Based Moisture-Resistant Wood Adhesives by using Tannic Acid- a Review of Recent Advances

In recent years, there has been a significant increase in attention toward the development of environmentally friendly materials, particularly in the adhesive industry. The wood industry is one of the largest consumers of adhesives. Synthetic wood adhesives are primarily based on urea-formaldehyde and melamine-formaldehyde resins, which release formaldehyde during manufacturing and use which is highly harmful to human health. In recent years, regulations and guidelines prohibiting the use of formaldehyde-releasing compounds have been established in most countries. Consequently, extensive research has been conducted to replace formaldehyde-based wood adhesives. Tannic acid-based adhesives, as a natural and abundant compound, have gained attention as a promising material for the synthesis of fully bio-based wood adhesives due to their unique properties, such as high adhesion, moisture resistance, biocompatibility, and antimicrobial properties. This review article summarizes the latest advancements in the use of tannic acid for producing moisture-resistant wood adhesives, inspired by natural structures and mechanisms. First, the properties of tannic acid and its role in improving adhesion and water resistance are discussed. Then, various methods of modifying tannic acid and combining components to achieve high-performance adhesives are reviewed. Additionally, the impact of combining tannic acid with other natural materials, such as proteins, polysaccharides, and nanoparticles, to enhance mechanical properties and moisture resistance is explored. This study demonstrates that tannic acid-based adhesives have significant potential as a sustainable and efficient alternative to petroleum-based synthetic adhesives in the wood industry, particularly in humid or underwater environments.