Grape cluster-structured CNT@ZIF-8 hybrids anchored on electrospun PPENK veils for enhanced interlaminar toughness of CF/PPESK composites

A “grape cluster”-like multiscale hybrid structure (CNT@ZIF-8) was successfully constructed by in-situ growth of ZIF-8 nanoparticles on CNT surfaces. • Molecular dynamics simulations revealed the interaction mechanism between CNT-COOH and ZIF-8 at the molecular level. • The CNT@ZIF-8 hybrids were uniformly anchored onto electrospun fibers via a combined electrospinning–electrospray process to achieve multiscale reinforcement. • G IC ,ini and G IC ,prop increased by 59% and 50% respectively, G IIC rose by 192%; and in-plane properties were significantly improved. In fiber-reinforced high-performance thermoplastic composites, the surface inertness of carbon nanotubes (CNT) limits interfacial bonding with the polymer matrix, significantly reducing their reinforcing and toughening efficiency. To address this, we propose a surface modification strategy for high-temperature processing: in-situ growth of ZIF-8 nanoparticles on CNT surfaces to construct a “grape-like” multiscale hybrid (CNT@ZIF-8). Using combined electrospinning–electrospray, CNT@ZIF-8 is uniformly loaded onto electrospun fibers, and the resulting mats are introduced into the interlaminar region of CF/PPESK composites, achieving synergistic strength and toughness enhancement. Compared to the unmodified composite, Mode I interlaminar fracture toughness (initiation and propagation) increases by 59% and 50%, respectively; Mode II toughness improves by 192%; flexural strength and interlaminar shear strength increase by 36% and 27%, respectively. The enhanced performance is attributed to two factors: (1) CNT@ZIF-8 anchoring on electrospun fibers improves fiber–matrix interfacial bonding; (2) the nanoscale rough structure of ZIF-8 on CNT enhances mechanical interlocking with the resin matrix. Molecular dynamics simulations reveal strong hydrogen bonding between CNT and the ZIF-8 precursor (2-methylimidazole). During loading, the “grape-like” hierarchical structure suppresses CNT debonding and sliding, promoting energy dissipation via enhanced interfacial friction and multi-path crack propagation, thereby greatly increasing energy absorption during fiber pull-out. This work provides a new strategy and theoretical basis for surface modification of CNT in high-temperature resistant thermoplastic matrices.