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 con-ductivity 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 orienta-tion and that high pressure and thermal treatment during the hot-pressing process facilitated the formation of Jr-Jr interactions, resulting in an exceptionally high thermal conductivity in HP-PI.

Automated summary

Due to their remarkable properties, polymers are widely used in industry. However, the low thermal conductivity of polymers poses limitations. In this study, we demonstrate that increasing chain orientation and intermolecular interaction can enhance the thermal conductivity of polyimide (PI). Our results show that electrospun PI nanofibers and hot-pressed nanofibrous PI films have significantly higher thermal conductivity values compared to solution-casting PI films. Molecular-scale structural characterizations reveal the mechanisms behind the improved thermal conductivity.