Tailoring chain-packing structure in co-blended aramid composites for high mechanical and insulating performance

Abstract

Aramid paper materials, renowned for their exceptional mechanical properties, insulting capabilities, and thermal stability, are crucial for next-generation electrical and electronic devices. Among them, the poly(m-phenylene isophthalamide) (PMIA) paper exhibits practical potential through its simple and cost-effective preparation methods. However, the traditional PMIA paper produced by the wet-laid process suffers from interfacial defects, while the PMIA nanopaper prepared via protonation is more homogeneous, yet lacks the crystalline structure to sustain high mechanical strength. Here, PMIA is blended with a heterocyclic aramid (HA), a derivative of aramid, to prepare co-blending paper. The HA contains benzimidazole groups in its molecular structure, providing more hydrogen bond-forming sites that enhance the mechanical robustness. The strengthened hydrogen bonding network facilitates a stronger interaction between PMIA and HA, as well as a reduced interchain spacing, which tailors the chain packing structure with a smaller free volume fraction, conducive to a higher breakdown strength. Additionally, the HA and PMIA share a common solvent for co-blending, highly simplifying the preparation process. At an optimized HA content of 20 wt%, the PMIA/HA co-blending paper exhibits high structural integrity, characterized by a dense and compact configuration. Its Young's modulus is 4.6 GPa and breakdown strength is 300.6 kV mm⁻¹. Moreover, hydrogen bonds effectively suppress dielectric loss. Due to its superior flexibility, colorability, and flame retardancy, the aramid co-blending paper exhibits versatile and high-performance features for a wide range of applications.