Cob Wall Inspired Mechanically Robust, Hydrolysis Resistant and Recyclable Semi-Interpenetrating Polyimine Networks

Dynamic covalent polymers hold significant promise for applications in aerospace, electronics, and biomedicine due to their adaptive repair and recyclability. However, conventional dynamic polymers suffer from insufficient mechanical strength, poor hydrophobicity, and limited heat resistance, while balancing self-healing properties with robustness remains challenging. Inspired by the ancient Chinese technique of cob wall construction, we develop aramid nanofiber (ANFs)-reinforced dynamic polyimine composites (Cardo-DPI/ANFs) by integrating ANFs into a fluorene-containing polyimine matrix. The composite exhibits enhanced mechanical performance (18.8% increase in tensile strength), reliable hydrophobicity (water absorption rate is 3.5% vs 6.4%), and elevated glass transition temperature. Notably, Cardo-DPI/ANFs demonstrate multi-level recyclability, enabling transformation between films and hydrophobic aerogels with pearl-necklace-like porous structures via solvent-mediated reprocessing. These composites also retain over 90% of its original tensile strength after multiple reprocessing cycles. The work provides a sustainable strategy for designing high-performance dynamic composites, which can play a key role in mitigating global environmental pollution.