Biomimetic Winding-Interlocked PPTA Nanocomposite Paper Reinforced by Polyarylate Nanofibers for Robust Electrical Insulation

High-performance aramid insulating paper that simultaneously combines mechanical robustness, dielectric strength, and environmental durability is highly desirable, yet remains difficult to realize because weak interfiber adhesion and loose network structures in conventional poly (p-phenylene terephthalamide) (PPTA) paper fundamentally limit stress transfer and electric-field regulation. Here, inspired by the interwoven architecture of natural rattan stems, a winding-interlocked PPTA/polyarylate (PAR) nanocomposite insulating paper is engineered by integrating thermally reprocessable PAR nanofibers with a heat-activated interfacial fusion strategy. The PAR nanofibers act as nanoscale binder-reinforcers that bridge adjacent PPTA fibers, while strong interfacial coupling, governed by hydrogen bonding and π-π stacking, promotes structural densification, suppresses space-charge accumulation, and homogenizes the local electric-field distribution. This biomimetic multiscale architecture enables the simultaneous optimization of mechanical load transfer and dielectric insulation. At a PAR loading of 30 wt%, the composite paper achieves a breakdown strength of 130.3 kV/mm and a tensile strength of 39.124 MPa, which are approximately 4.8 times and 1.9 times higher than those of commercial aramid paper, respectively. Notably, the paper retains excellent dielectric performance even after thermal aging, UV exposure, and repeated folding/deformation, demonstrating outstanding weather resistance and mechanical reliability. This work provides a scalable strategy for designing next-generation aramid-based insulation papers for electrical insulation applications under harsh conditions. Highlights Polyarylate nanofibers exhibit secondary thermoprocessing characteristics. Nanocomposite insulation paper design via entangled-interlocked fiber networks. Excellent dielectric properties and extreme-condition tolerance. Achieved 130.3 kV/mm breakdown strength in nanocomposite paper. Dual-network interlocking architecture suppresses charge accumulation and field distortion.