Adhesive, self-healing, and stretchable lignin–acrylic acid–organosilane composite for bifunctional uses

The development of sustainable and multifunctional polymeric materials has recently gained considerable attention. Herein, a flexible and adhesive lignin-acrylic acid-organosilane polymeric composite was successfully synthesized through a one-pot free-radical copolymerization of lignin, acrylic acid (AA), and 3-(trimethoxysilyl)propyl methacrylate (SiMMA). The incorporation of SiMMA enabled the in-situ formation of crosslinking networks through siloxane formation and CC polymerization, which enhanced the structural integrity, flexibility, and self-healing ability of the fabricated composite. The synthesized polymeric material was stretchable with strong adhesion to wood, metal, and polymeric surfaces. When the fabricated polymer was coated on wood, the presence of organosilane significantly improved the flame-retardant performance of wood through the formation of protective SiO₂ layers. In addition, due to the presence of OH, COOH, and aromatic moieties, the synthesized polymeric composite demonstrated high adsorption capacity toward methylene blue dye and Cu, Cr, Co, and Ni ions dissolved in water via electrostatic interactions, π-π stacking, and van der Waals forces, confirming its effectiveness for wastewater decontamination. Overall, this study presents a facile strategy for developing a lignin-based polymeric composite with integrated adhesive, self-healing, and flame-retardant properties, offering strong potential for multifunctional applications, such as flame-retardant coatings and environmental remediation.