Boron Nitride Nanosheets Modified with Polydopamine and Polyimide Nanofibers as Flexible Thermal Management Materials

Inspired by the structure and production process of textiles, a zigzag aligned structural design was proposed to fabricate flexible thermally conductive nanocomposites via a facile, scalable lamination process of electrospun polyimide (PI) nanofibers. More specifically, polydopamine (PDA) was used as a modifier to functionalize boron nitride nanosheets (BNNS), and the p-BNNS/PI nanofilm was prepared using the electrostatic spinning technique. Subsequently, the nanofilm was rolled into vertically oriented cylinders, and vacuum-assisted impregnation of polydimethylsiloxane (PDMS) was carried out, resulting in the construction of p-BNNS/PI/PDMS nanocomposites. The obtained nanocomposites not only demonstrated strong anisotropy and significantly enhanced thermal conductivity but also possessed excellent electrical insulation performance. The nanocomposites with 10 wt % p-BNNS exhibited both an ultrahigh out-of-plane thermal conductivity of 1.26 W/m K and a high volume resistivity of approximately 1015 Ω cm. Additionally, the nanofilm maintained excellent flexibility and remained intact even after kneading for 60 s while exhibiting a maximum tensile strength of 29.7 MPa. This work provided an effective method to establish a continuous thermal conductive network and further expanded the thermal management applications of polymer-based nanocomposites in electronic packaging and other fields.