Enhancing the thermal conductivity of amorphous polyimide by molecular-scale manipulation

Due to their remarkable mechanical, chemical, and electrical properties, polymers are widely utilized in industry. However, the low thermal conductivity of polymers limits more extended applications of them that require high degrees of heat dissipation. Here, we demonstrate that the combination of increased chain orientation and powerful intermolecular interaction can boost the thermal conductivity of polyimide (PI). The thermal conductivity values of electrospun individual PI nanofibers (INF-PI) and hot-pressed nanofibrous PI films (HP-PI) formed with these nanofibers were as high as 0.44 and 0.98 W m−1 K−1, respectively, at room temperature. The former and the latter were measured by the suspended microdevice and hot-disk methods, respectively. These values are considerably higher than the solution-casting PI film (SC-PI) value of 0.1 W m−1 K−1. Furthermore, molecular-scale structural characterizations revealed that the electrospinning process improved chain orientation and that high pressure and thermal treatment during the hot-pressing process facilitated the formation of π–π interactions, resulting in an exceptionally high thermal conductivity in HP-PI.