Synergistically Constructing High-Dielectric Poly(m-phenylene isophthalamide)/Silica/Cellulose Nanofiber Composite Insulation Paper through Dynamic Covalent Chemistry and Hydrogen Bonding

The rapid advancement of modern power equipment and high-power devices has imposed increasingly stringent demands upon the mechanical and dielectric properties of electrical insulation materials. Herein, we report a poly(m-phenylene isophthalamide) (PMIA) composite insulating paper with excellent dielectric breakdown strength, reliable mechanical properties, and high thermal stability. Enhanced surface activity of PMIA is achieved through surface modification, facilitating the synergistic integration of modified PMIA (MPMIA), bovine serum albumin (BSA)/silica (SiO2), and cellulose nanofiber (CNF) into composite paper using dynamic covalent bonds and hydrogen bonding. The prepared MPMIA–BSA/SiO2–CNF composite paper exhibits a laminated stacked structure with high tensile strength (32.68 MPa) and strain at break (9.57%). Meanwhile, MPMIA–BSA/SiO2–CNF composites have excellent dielectric breakdown strength (24.75 kV/mm) and good temperature resistance. Therefore, the MPMIA–BSA/SiO2–CNF composite paper has a broad application prospect in the field of high-voltage and high-power electrical equipment insulation.