Vacuum-assisted nano-network co-infiltration enables nanoconfined multiscale CNT/polyimide CFRPs with exceptional thermal stability and multifunctionality

The development of ultra-high-temperature-resistant composite materials has attracted increasing attention, particularly through the use of high glass transition temperature (Tg) polymers to enhance the thermal stability of carbon fiber reinforced polymers (CFRPs). Introducing nano-network architectures to induce nanoconfinement effects offers a promising route for further performance enhancement; however, challenges remain in constructing nano-networks on carbon fiber surfaces and impregnating high-viscosity resins into these dense structures. Herein, we report a vacuum-assisted nano-network co-infiltration (VANCI) strategy that enables the simultaneous formation of carbon nanotube (CNT) nano-networks and polyimide (PI) matrix infiltration, creating a hybrid multi-scale architecture. By combining ultrasonication-assisted dispersion with vacuum filtration, CNTs and PI powders are co-infiltrated into carbon fiber fabrics, enabling the in-situ formation of a continuous CNT nano-network concurrent with resin impregnation. This process induces a pronounced nanoconfinement effect, confining PI chains within the interconnected CNT framework across inter- and intra-tow regions. At a CNT loading of 1.5 wt%, the composite exhibits a Tg of 437 °C and a 5% weight loss temperature of 579.9 °C, representing increases of 41 °C and 18 °C, respectively, compared to neat CFRP. In addition, the CNT nano-network significantly enhances electrical and thermal conductivity, while also improving wear resistance through a reduced coefficient of friction and wear rate. This work provides a scalable route to multifunctional CFRPs for aerospace applications with extreme thermal environments.