Bio-inspired robust and highly thermal conductive BNNS/PBO nanofiber composite films with excellent thermal stability, wear resistance, and adjustable photothermal properties

Thermally conductive films are essential interface materials placed between a heat source and a heat sink to address the heat dissipation issue, especially for electronic devices confined in narrow spaces. However, developing a thermally conductive film with a combination of high thermal conductivity, good mechanical strength, and excellent electrical properties remains a challenging task. In this study, we aimed to overcome this challenge by preparing composite films using polydopamine (PDA) nanoparticle-functionalized boron nitride nanosheet (BNNS) and poly-p-phenylene benzodiazole (PBO) nanofiber through a combination strategy of deprotonation and hot-pressing techniques. The resulting BNNS@PDA/PBO nanofiber composite film demon-strated an impressive in-plane thermal conductivity of 45.15 W/(m & sdot;K), with only 37.5 wt% of BNNS@PDA. This represents the optimal value of thermal conductivity enhancement of per unit BNNS. Detailed analysis of the heat conduction mechanism confirmed that the PDA-induced nacre lamellar structure and enhanced interfacial interaction were key factors contributing to this high-performance realization. Meanwhile, other necessary properties during film realistic service such as strong mechanical properties (ultimate tensile strength = 104.9 MPa), excellent thermal stabilities (T5% = 670.03 celcius), ultra-low thermal expansion (2.29 ppm/K), low dielectric loss (tan delta = 0.03) and good scratch resistance (wear rate:6.85 x 10-11 m3 N-1 m-1) are also integrally achieved. Intriguingly, the as-prepared films also exhibit a tunable photothermal conversion performance (70 degrees C rise @0.5 W/mm2 for 120 s). This multifunctionality, combined with its superior performance, highlights the great po-tential of BNNS@PDA/PBO nanofiber composite films in heat management applications, such as small electronic devices, intelligent wearable equipment, and photothermal therapy.