Cactus-Spine Inspired Aligned CNT-Electrospun Fibers for Interlaminar Toughening of CF/PPESK Composites: Guiding, Arresting, and Enabling 3D Propagation for Energy Dissipation

Electrospinning-electrospray assembles aligned CNT on fibers, overcoming resin viscosity limits. • CNT embedded in fibers form cohesive interlocking, achieving strong mechanical interlock. • Guide–arrest–3D propagation mechanism enables multiscale crack deflection for high toughening. • G IC ,ini and G IC ,prop increased by 51% and 44% respectively, G IIC rose by 178%; flexural strength, flexural modulus, and ILSS also improved. Conventional carbon fiber reinforced high-performance thermoplastic (CFRHPTP) composites suffer from inherent dispersion deficiency and alignment challenges of carbon nanotubes (CNT) in high-viscosity matrix, leading to suboptimal interlaminar toughening efficiency. To address this critical issue, a bioinspired multiscale toughness and reinforcement paradigm for carbon fiber reinforced poly(phthalazinone ether sulfone ketone) (CF/PPESK) composite was proposed. Specifically, drawing inspiration from the geometric microstructure of cactus spines (high aspect ratio and directional growth), the vertically aligned CNT-anchored electrospun fiber veils were developed by the synergistic electrospinning-electrospraying protocol, and were strategically inserted into the interlaminar zones of CF/PPESK composites. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations confirmed that the electrospun fibers were firmly anchored with CNT, successfully constructing a three-dimensional reinforcement network. Furthermore, this architecture significantly enhanced the toughness of CF/PPESK composites, with the initiation and propagation values of mode I fracture toughness increased by 51 % and 44 %, respectively, while mode II fracture toughness improved remarkably by 178 %. Notably, flexural strength, flexural modulus, and interlaminar shear strength were enhanced by 25 %, 24 %, and 18 %, respectively. Microstructural analysis revealed that the excellent toughening effect originates from a three-dimensional crack deflection, guidance, and arrest mechanism formed by the synergistic interaction between electrospun fibers and aligned CNT. This micro-nano synergistic mechanism significantly promotes fracture energy dissipation and simultaneously enhances the in-plane strength of the composite. This work provides an innovative and efficient pathway to overcome the interlaminar toughness limitations in high-viscosity resin-based composites. A one-step electrospinning-electrospray assembly is developed to anchor aligned carbon nanotubes (CNT) onto electrospun fibers, overcoming resin viscosity limitations to achieve controlled nanoscale orientation within composites. This bioinspired micro-nano architecture features CNT embedded within the electrospun fibers and forming cohesive interlocking, achieving a strong mechanical interlocking effect. Introduced into the interlaminar region, this architecture triggers a "guide–arrest–three-dimensional propagation" crack deflection mechanism, significantly enhancing toughening efficiency. As a result, Mode I initiation toughness increases by 51%, Mode I propagation toughness by 44%, and Mode II interlaminar toughness by 178%, with simultaneous improvements in flexural strength (25%), modulus (24%), and ILSS (18%). Download: Download high-res image (363KB) Download: Download full-size image