Unraveling the Intricate Interaction: Bonding Mechanism Between Tannic Acid and Wood Fibers

Due to the biodegradable, biocompatible, sustainable, and renewable properties of lignocellulosic materials, there is growing interest in developing functional materials based on lignocellulosic components using green strategies. For example, the surface of lignocellulosic materials can be modified using polyphenols with inherent characteristics such as metal chelation and reducibility to prepare functional materials with flame retardant, antibacterial, and self-cleaning properties. Understanding the fundamental interaction mechanisms between lignocellulosic materials and polyphenols is crucial for these applications and the design of lignocellulosic-based functional materials. In this study, we used wood fibers (WFs) and tannic acid (TA) as typical representatives of lignocellulosic materials and polyphenols, respectively. We combined adsorption isotherm models and density functional theory simulations to reveal the interaction mechanisms between the main components of WFs (cellulose, hemicellulose, and lignin) and TA. Cellulose and hemicellulose primarily interacted with TA through hydrogen bonding, electrostatic interaction, and hydrophobic interaction, while lignin-TA interactions are hydrogen bonding and electrostatic interaction. For WFs, their pore structure and exposed surface components determined their binding with TA. The adsorption of TA on WFs followed the Langmuir model for monolayer adsorption, with the main driving forces being hydrogen bonding, electrostatic interactions, and van der Waals forces between surface cellulose components and TA. Our findings provide new insights into the interaction mechanisms between lignocellulosic materials and polyphenols, offering valuable guidance for the development of lignocellulosic/polyphenol composite functional materials with environmental, biomedical, and engineering applications.