Eco‐Friendly Dopamine Vanillin Schiff Base Coating for Multifunctional Cotton With Molecular Dynamics Insights

ABSTRACT Prevailing multifunctional coatings derived from fluorinated and other non‐degradable materials pose significant environmental concerns during both synthesis and disposal. To mitigate this issue, extensive research has focused on developing eco‐friendly multifunctional coatings from renewable materials. Here, we engineered a sustainable multifunctional coating for cotton textile via a biobased dopamine hydrochloride (DA)‐vanillin‐octadecylamine (ODA) Schiff base reaction using a facile infrared (IR) dyeing process. This enabled ODA to react with the quinone groups of DA to generate a hydrophobic surface via its long alkyl chains, without the use of nanoparticles or harmful solvents. To further elucidate the coating assembly mechanism, molecular dynamics (MD) simulations were performed, revealing dopamine as the dominant anchoring unit to cellulose, while ODA preferentially interacts with the DA‐vanillin conjugate, and simulated WCA closely matched the experimental values, supporting the proposed coating assembly mechanism. This proposed coating exhibited hydrophobicity with a water contact angle (WCA) of 123.5°, an ultraviolet protection factor (UPF) of 174, antioxidant activity of ~70%, antibacterial activity, mild fragrance, self‐cleaning properties, and good color strength (K/S). Furthermore, this functional modification process preserved the inherent useful properties of cotton fabric, like tensile strength, air permeability, and bending length. This sustainable strategy, achieved without including any nanoparticles and harmful solvents, clearly highlights an eco‐friendly approach over the traditional multifunctional coating process. More importantly, this coating prolonged the hydrophobic nature up to five washes. These findings underscore the potential of vanillin‐DA Schiff base as a viable candidate and hold promise in various industrial applications, including biomedical, sports and decoration.