Self-healing and recyclable vitrimers enabled by dual-dynamic cross-linked networks with biomass citric acid-diaminodecane salt modified hydrotalcites

Traditional petroleum-based synthetic leather exhibits multiple limitations, including non-sustainability, non-biodegradability, environmental contamination and resource inefficiency. Bio-based polymers serve as sustainable matrix materials for synthetic leather production, effectively mitigating petroleum dependence while enabling sustainable manufacturing. In this work, epoxidized natural rubber (ENR)/citric acid (CA)-decanediamine (DA) salt intercalated layered double hydroxides (LDHs) nanocomposites were prepared. The nano-composites were specifically designed as surface-layer components for bio-based synthetic leathers. LDHs with interlayer spacing (17.9 & Aring;) were synthesized through ion exchange, enabling effective exfoliation and homogeneous dispersion within the ENR matrix. The crosslinking characteristics, mechanical and dynamic properties of ENR composites under different CA-DA salt modified LDHs (CA-DA LDHs) concentrations were surveyed in detail. The shortest vulcanization time (t90 = 21.9 min) and highest torque were observed in ENR vitrimers containing 30 wt% nano-filler loading. A progressive increase in crosslink density and mechanical performance was recorded with increasing CA-DA LDHs contents. ENR30 demonstrated the maximum tensile strength of 8.0 MPa, significantly exceeding the 1.3 MPa measured for unfilled ENR0, which was attributed primarily to the enhanced crosslink networks formation and optimized LDHs dispersion characteristics. Notably, the dynamic properties of ENR were conferred by dual reconfigurable cross-linked network comprising beta-hydroxy ester bonds and hydrogen-bonding interactions, which facilitated rapid stress relaxation (tau* = 53 s at 200 degrees C for ENR30) and thermally induced topological rearrangement. This architectural design enabled recovery efficiencies exceeding 90 % after multiple reprocessing cycles, demonstrating excellent network reconfigurability. With the combination of mechanical strength and dynamic activity, ENR vitrimers exhibit potential as the bio-based surface layer in synthetic leather to replace traditional petroleum-based leather.