Synergistically Constructing\nHigh-Dielectric Poly(<i>m</i>‑phenylene isophthalamide)/Silica/Cellulose\nNanofiber\nComposite Insulation Paper through Dynamic Covalent Chemistry and\nHydrogen Bonding

The rapid advancement of modern power equipment and high-power\ndevices has imposed increasingly stringent demands upon the mechanical\nand dielectric properties of electrical insulation materials. Herein,\nwe report a poly(<i>m</i>-phenylene isophthalamide) (PMIA)\ncomposite insulating paper with excellent dielectric breakdown strength,\nreliable mechanical properties, and high thermal stability. Enhanced\nsurface activity of PMIA is achieved through surface modification,\nfacilitating the synergistic integration of modified PMIA (MPMIA),\nbovine serum albumin (BSA)/silica (SiO<sub>2</sub>), and cellulose\nnanofiber (CNF) into composite paper using dynamic covalent bonds\nand hydrogen bonding. The prepared MPMIA–BSA/SiO<sub>2</sub>–CNF composite paper exhibits a laminated stacked structure\nwith high tensile strength (32.68 MPa) and strain at break (9.57%).\nMeanwhile, MPMIA–BSA/SiO<sub>2</sub>–CNF composites\nhave excellent dielectric breakdown strength (24.75 kV/mm) and good\ntemperature resistance. Therefore, the MPMIA–BSA/SiO<sub>2</sub>–CNF composite paper has a broad application prospect in the\nfield of high-voltage and high-power electrical equipment insulation.