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

Abstract

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.

Dry-Contact Thermal Interface Material with the Desired Bond Line Thickness and Ultralow Applied Thermal Resistance

“…Now, considerable attention has been paid to the development of high- k materials, and many attempts at highly thermally conductive TIMs have been witnessed in the past two decades. − For example, carbon nanotubes (CNTs) are the ideal TIM precursor due to their one-dimensionally highly thermo-conductive characteristic (≥2000 W/m K) . Various vertically aligned technologies were adopted to successfully fabricate perpendicular CNTs-array TIMs, whose out-of-plane k were reported to be able to exceed 70 W/m K. , Similar results can also be found in vertical graphene TIMs, for example, a mechanical-machining processed graphene monolith was manifested to exhibit an out-of-plane k as high as 143 W/m K, which is on par with some metals and alloys. , In addition to the above high- k carbons, other TIMs include liquid metals, ,, inherently thermally conductive polymers, polymer composites (i.e., thermal grease, gel, and pad), − and phase change materials. − Looking at the previously reported TIMs, the manipulation of the anisotropic k and making it superb in the thickness direction is not a very difficult thing; however, the achievement of a low R eff when these TIMs are applied in a sandwiched heat source-sink structure remains a formidable challenge.…”

Recyclable and elastic highly thermally conductive epoxy-based composites with covalent–noncovalent interpenetrating networks

“…8 Therefore, in recent years, researchers have conducted extensive research on designing and preparing highly thermally conductive polymer materials, by synthesizing polymer matrices with intrinsically high thermal conductivity or loading with inorganic thermally conductive fillers. 9–14…”