Pyridine Functionalization: A Facile Route to Recycled Biobased Itaconate Elastomer/Lignin Composites with Superior Mechanical and Damping Performance

A massive global annual demand exists for elastomers applied in tires, seals, and shock absorbers. Against the backdrop of sustainable development, next-generation damping elastomers are expected to integrate multiple functionalities, notably high biobased content and recyclability. Nevertheless, the fabrication of such advanced elastomers remains fraught with challenges. This work designs and synthesizes pyridine-functionalized biobased elastomers (polar rubber matrix) using the biobased monomer diethyl itaconate in conjunction with partially petroleum-derived butadiene and 4-vinylpyridine via environmentally benign emulsion polymerization. Subsequently, damping elastomer composites (VPx-L-DIH) with a substantial bio‑based fraction are constructed by employing lignin as a biobased reinforcing filler and 1,6-diiodohexane (DIH) as a crosslinking agent. Due to the energy dissipation mechanism of the dynamic network (hydrogen bonds and Zn2+-based coordination bonds), VPx-L-DIH composites show excellent mechanical properties (tensile strength of 16.8 MPa) and a broad, adjustable damping temperature range (96.9 °C, tan δ > 0.3). By virtue of the exchange reaction through C-N transalkylation in quaternized pyridine units, the VPx-L-DIH composites show good reprocessability. Furthermore, utilizing the photothermal effect of lignin, these materials exhibit significant photothermal responses under NIR irradiation. This work offers a viable sustainable approach for the structural design of damping elastomers and lignin-based multiple functional composites.