Rigidity-tuned fluoroaromatic imine vitrimers yield ultra-high-strength, self-healing, and recyclable shape memory polybutadiene rubbers

Abstract

Dynamic covalent chemistry provides a pathway to sustainable and recyclable rubber materials, yet the intrinsic lability of reversible bonds typically compromises mechanical integrity. Herein, we report a fluoroaromatic trialdehyde cross-linker that drives the catalyst-free formation of highly rigid imine networks in amino-functionalized 1,2-polybutadiene (PBD). By judiciously tuning the cross-linker content, we achieve an unprecedented balance of robustness and adaptability. The optimal network exhibits an ultimate tensile strength of 32.1 MPa and a Young's modulus of 307 MPa, both of which are record values for recyclable PBD systems. Stress-relaxation experiments reveal a rapid topological rearrangement with an activation energy of 56.8–72.1 kJ mol⁻¹, ensuring efficient reprocessing and recyclability. The dynamic imine bonds underpin >97% strength after thermally driven self-healing and can trigger shape programming at temperatures above T_g. Incorporation of 10 wt% carbon nanotubes produces composites that retain mechanical performance through multiple solid-state reprocessing cycles, yet can be cleanly disassembled in n-butylamine at ambient temperature, allowing for quantitative recycling and reuse of carbon nanotubes. Our strategy demonstrates that embedding fluoroaromatic rigidity into imine vitrimers overcomes the long-standing trade-off between strength and recyclability, establishing a general design principle for next-generation high-performance, eco-conscious rubbers.