Synergistic Design of Flexible Covalent Networks, Multiple Hydrogen Bonds, and Rigid Moieties for Bio-Based Elastomers with High Oil Resistance, Gas Barrier, and Tailored Strength–Toughness

Oil-resistant bio-based rubber combining high mechanical performance with excellent gas barrier is essential for sustainable elastomer applications. However, conventional polar modification or filler reinforcement routes involve complex processing and always sacrifice extensibility, restricting their use in dynamic seals. Herein, a dual cross-linked network was constructed in epoxidized natural rubber (ENR) by simple blending, using succinic acid (SA) as a flexible covalent cross-linker and 5-benzyl-3,6-dioxo-2-piperazineacetic acid (DKP) as a rigid aromatic hydrogen-bonding donor. The synergistic integration of flexible covalent networks, rigid aromatic moieties, and dynamic multiple hydrogen bonds endows the resulting elastomer with exceptional comprehensive properties, in which the optimized formulation (0.5 phr SA and 12 phr DKP) achieves a tensile strength of 7.64 MPa, an elongation of 439.88%, and a Young’s modulus of 16.31 MPa, with excellent oil resistance (mass change < 8% and surface area change < 2% after 72 h in IRM903 oil) and outstanding gas barrier performance (an oxygen permeability coefficient as low as 5.6 × 10 –11 cm 3 ·cm/(cm 2 ·s·cmHg)). Furthermore, the dynamic nature of the hydrogen bonds and ester linkages enables remarkable recyclability without compromising oil resistance after reprocessing. This facile strategy enables high-performance bio-based elastomers combining oil resistance, gas barrier, robust mechanics, and recyclability for applications in automotive, aerospace, and oil drilling fields.