Polymer Films with Metal-Like Thermal Conductivity, Excellent Stability, and Flame Retardancy

Polymers often have thermal conductivities that are too low to be used directly in thermal management applications. In this study, a poly(p-phenylene-2,6-benzobisoxazole) (PBO) film is prepared through a sol-gel-film conversion and annealing method that utilizes PBO nanofibers as building blocks. The polymer film shows an in-plane thermal conductivity of 36.7 W mK(-1), which is two orders of magnitude higher than those of most polymers (<0.5 W mK(-1)) and 2.4 times that of 304-stainless steel. The high thermal conductivity is attributed to the highly oriented 3D interconnected nanofiber network resulting from the fine-tuning sol-gel-film conversion, and the annealing that further enhances the ordering of the PBO chains and the interactions between the nanofibers. Moreover, the PBO films exhibit excellent mechanical strength, thermal/chemical stability, electrical insulation, flame retardance, and improved UV resistance. The lightweight, robust, and easily processed PBO film with a metal-like thermal conductivity has promising potential thermal management applications.