Surface-functionalized mica enables pangolin-scale-inspired self-welded polyarylate nanofiber insulating paper with enhanced dielectric and mechanical reliability

Overcoming the interface adhesion and structural strength limitations of traditional insulating paper. • Enhancing dielectric and mechanical properties via PAR nanofiber self-welding strategy. • Achieved 134.48 kV mm −1 breakdown strength in TMS@Mica/PAR −a 5.3 increase vs. aramid paper. High-voltage insulation systems require dielectric papers that can withstand elevated temperatures and complex mechanical deformation, yet conventional aramid and mica papers suffer from weak interfacial adhesion and limited structural robustness. Inspired by the hierarchical overlapping structure of pangolin scales, we developed a surface-functionalization-assisted self-welding strategy to fabricate mica/polyarylate nanofiber composite insulating paper with robust organic/inorganic interfaces. Sericite mica platelets were modified with trimethoxy(2-phenylethyl)silane, forming covalently anchored organosilane layers through condensation between silanol groups and surface hydroxyls. The introduced phenylethyl groups promoted π-π interactions with thermotropic liquid-crystalline polyarylate nanofibers, thereby enhancing mica dispersion, interfacial wettability, and adhesion. Through wet ball milling and controllable hot pressing, the surface-functionalized mica platelets were uniformly embedded and aligned within the polyarylate nanofiber network, forming a pangolin-scale-like laminated architecture. During hot pressing, the thermoplastic nanofibers underwent in situ self-welding, producing compact, continuous, and defect-suppressed interfacial regions. The combined effects of covalent anchoring, π-π coupling, bioinspired layered assembly, and interfacial densification reduced interfacial voids and local electric-field distortion. Consequently, the TMS@Mica/PAR paper exhibited a breakdown strength of 134.48 kV mm⁻ 1 , 25.14% higher than unmodified Mica/PAR paper and markedly exceeding commercial aramid paper and mica paper. After aging at 200 ℃ for 24 h, it retained a breakdown strength of 120.93 kV mm⁻ 1 and showed only slight degradation after repeated folding and crumpling, demonstrating excellent thermal stability and mechanical durability. Download: Download high-res image (229KB) Download: Download full-size image