Synthesis of Bisfuran-Based Long-Chain Biopolyamide Ionomers through Postpolymerization Modification

Furan-bearing polyamide (FPA) is a potential alternative to its petroleum-based counterparts owing to its sustainability and convenient preparation process. However, most FPAs exhibited unsatisfactory mechanical properties because of the furan ring in the backbone, which depressed the formation of an intermolecular hydrogen-bonding network. To circumvent these defects, we introduced the ionic interaction into bisfuran-based long-chain polyamides for the first time. The pendant metal ions aggregate via microphase separation to form dynamic physical cross-linking sites, thereby significantly enhancing the thermal and tensile properties of the resulting biobased polyamide ionomers. The maximum tensile strength of the polyamide ionomer reaches 10.7 MPa, with an elongation at break of 177.5%. Notably, the mechanical and processability properties of the polyamide ionomers are synergistically optimized through regulation of the polymer chain network by alkali metal ions (Li⁺, Na⁺, K⁺, etc.). The polyamide ionomers exhibit excellent reprocessability with no significant decrease in tensile strength after three cycles of repeated processing. This study highlights the potential of polyamide ionomers for practical application, offering a sustainable and high-performance alternative to conventional petroleum-based polyamides.