Biomimetic Nacreous Composite Films toward Multipurpose Application Structured by Aramid Nanofibers and Edge-Hydroxylated Boron Nitride Nanosheets

High-performance dielectric film is one of the most promising materials for comprehensive applications ranging from high-voltage electrical equipment to high-power electronic devices. We here report the fabrication of biomimetic nacreous multifunctional composite films by self-assembling nanoscale building blocks of one-dimensional (1D) aramid nanofibers (ANFs) and two-dimensional (2D) edge-hydroxylated boron nitride nanosheets (BNNS-OH). Synchronously, poly(vinyl alcohol) was introduced as soft glue to improve the interfacial interaction between ANFs and BNNS-OH by building a three-dimensional (3D) hydrogen-bond network. Attributing to the well-designed nanostructure and favorable interfacial hydrogen bonding, the resultant composite films exhibited a ultrastrong tensile strength (∼329.6 MPa), a high thermal conductivity (16.03 W m–1 K–1), outstanding dielectric properties, superior thermostability, and long life. Moreover, these synergistic properties of composite films were tunable by changing the contents of BNNS-OH to accommodate the requirements of multipurpose applications in the development of advanced insulation systems and thermal management materials.