Simultaneously Improving Lignin Dispersion and Interfacial Interaction in Rubber/Lignin Composites by Using Deep Eutectic Solvent as a Highly Effective Modifier

Lignin, the most abundant aromatic biomaterial on Earth, is widely available as a byproduct of the papermaking and biorefinery industries and could serve as a green filler for rubber. However, preparing high-performance and multifunctional rubber/lignin composites remains challenging due to the inhomogeneous dispersion of lignin in the rubber matrix and poor lignin–rubber interfacial adhesion. In this article, a facile lignin modification approach was proposed. Namely, we used a deep eutectic solvent (DES), composed of choline chloride and ZnCl2, to simultaneously improve lignin dispersion and enhance the rubber–lignin interaction by constructing metal–ligand coordination bonds at the rubber–lignin interface. The resulting elastomer composites exhibited significantly enhanced mechanical and oil-resistance properties. Moreover, the introduction of DES could improve the photothermal effect of the rubber/lignin composite. This scalable and environmentally friendly strategy is anticipated to provide novel inspiration for the large-scale utilization of lignin in elastomers.