Robust Self-Healing Polyimide Membrane through Synergistic Schiff Base and Cation-π Interactions

Although polyimides are widely recognized for their excellent thermal stability and mechanical strength, their inherent irreversibility severely limits their self-healing ability and recyclability. In this work, a self-healing polyimide membrane with outstanding thermal and mechanical performance was developed through a molecular design strategy incorporating Schiff base linkages and cation-π interactions into the polymer backbone. These dynamic and reversible interactions allowed the polymer chains to dissociate into polyimide oligomers and subsequently reconstruct under heat treatment in an acidic organic solvent, thereby enabling efficient self-healing. Meanwhile, the introduction of Ca 2+ ions markedly improved the tensile properties, solvent resistance, and glass transition temperature of the membranes while maintaining the excellent self-healing capability of PI–Ca0. For example, after 48 h of immersion in deionized water, HCl, NaOH, NMP, and DMF, the tensile strength of the PI–Ca50 membrane remained as high as 89.23, 85.27, 87.58, 80.97, and 81.95 MPa, with reductions of only 4.29%, 8.53%, 6.06%, 13.15%, and 12.10%, respectively, far superior to those of PI–Ca0. Furthermore, after scratch repair, offset repair, and one recycling cycle, PI–Ca50 maintained tensile strengths of 89.85, 86.57, and 89.47 MPa, significantly higher than those of PI–Ca0. This work provides a promising strategy for the development of high-performance, self-healable polyimides with potential applications in flexible electronics and sustainable energy devices.