Poly(Isoprene‐ Co ‐2‐Vinylpyridine) Constructed Covalent‐Coordinative Dual Network for Enhanced Mechanical and Viscoelastic Properties of Nitrile Rubber/Talc Composites

ABSTRACT Insufficient interfacial compatibility and weak adhesion between the filler and rubber matrix are key performance limiting factors for rubber/filler composites. A series of poly(isoprene‐ co ‐2‐vinylpyridine) (PIPPY) copolymers with different pyridine contents was designed and synthesized. Each copolymer chain contains vulcanizable double bonds, which enable covalent crosslinking, along with pyridine ligands that act as coordination sites for dynamic interfacial interactions. The copolymer was subsequently deposited onto talc surfaces via spray drying, thereby introducing dynamic coordination bonds into the filler‐rubber interphase. Through hydrogen bonding between pyridine groups and hydroxyl groups on talc, coordination interactions with Zn 2+ and Mg 2+ ions, and covalent bonding between isoprene units and the nitrile butadiene rubber (NBR) matrix, the copolymer becomes firmly incorporated into the rubber phase. This configuration establishes a covalent‐coordination dual‐network structure at the filler‐rubber interface, improving interfacial energy dissipation. Vulcanization tests revealed that incorporating PIPPY significantly shortened the optimum vulcanization time of the composites, indicating a pronounced acceleration of vulcanization. Modulated differential scanning calorimetry (MDSC) analysis showed a marked increase in the fraction of bound rubber chains, suggesting substantially improved filler‐rubber interfacial interactions. Mechanical testing demonstrated that the tensile strength and tear strength of the modified composites increased by up to 91.2% and 19.4%, respectively, while the compression set was reduced by as much as 22.0%. Moreover, owing to the reversible breaking and reformation of dynamic coordination bonds at the interface, the composites exhibited excellent energy dissipation capability under cyclic loading. Concurrently, residual strain was effectively mitigated, and both stress softening and stress relaxation were significantly reduced.