Synthesis of Polyimide Films With High Strength and Toughness Utilizing the Synergistic Effect of Coordination Interaction and Hydrogen Bonds Strategy

In this work, a 2,6-pyridine dicarboxylic hydrazide (PDDH) monomer was incorporated into polyimide (PI) to fabricate PDDH-Co-PI films featuring a dual physical cross-linked network based on metal–ligand coordination and intermolecular hydrogen bonding, as validated by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). Formation of the coordination complexes and hydrogen bonds within the PI backbone altered the molecular chain conformation and aggregation state, leading to enhanced intermolecular interactions and tighter chain packing. X-ray diffraction (XRD) analysis confirmed a significant increase in the chain packing coefficient ( K ) and a reduction in interchain spacing ( d ). Consequently, PDDH-Co-PI exhibited markedly improved mechanical properties: tensile strength increased by 27.57% ± 0.82%, Young's modulus by 72.19% ± 3.90%, and fracture energy rose from 24.75 to 55.83 MJ·m −3 (an enhancement of 125.56% versus pure PI). The volumetric wear rate decreased from 26.92 × 10 −6 to 5.284 × 10 −6 mm 3 N −1 m −1 , representing an 80.4% reduction. These results demonstrate that the synergistic effect of coordination crosslinking and hydrogen bonding yields high-strength, high-toughness and wear-resistant PI films, providing a new strategy for the design and application of high-performance polyimide materials. Highlights PDDH monomer results in collectively H-bonding/coordination cross-linked PI. Dual cross-linking yields tough and strong PDDH-Co-PI films. PDDH-Co-PI film demonstrates excellent wear reduction performance.