Lignin and plant oil-based composites toward strong adhesives with outstanding environmental tolerance

Lignin contains numerous polar groups that contribute to various physical effects when combined with other polymer materials, enhancing cohesiveness and enabling the resultant materials to be utilized effectively as robust adhesive materials. This work incorporates homogenized lignin into plant oil-based poly(ester amide) (PEA) via in-situ melt polycondensation, yielding high-performance lignin/PEA composite adhesives. The addition of lignin significantly increases hydrogen bond formation within the cross-linked structures, strengthening internal interactions and improving the temperature tolerance of the composites. Notably, at a low lignin content (3 wt%), the composites exhibit enhanced mechanical properties, including increased tensile strength, elongation, and toughness. However, higher lignin content (14 wt%) reduces performance due to the self-aggregation of lignin particles. Moreover, these lignin/PEA composites can be easily recycled through physical and chemical methods without compromising their mechanical performance. High adhesion strength can be achieved over a wide temperature range from −196 to 100 °C, demonstrating exceptional adhesion behavior in harsh environments. Overall, integrating lignin and PEA through in-situ melt polycondensation offers a promising strategy for developing sustainable, recyclable adhesives for demanding applications under extreme conditions.