Abstract
Dielectric materials with excellent thermally conductive and mechanical properties can enable disruptive performance enhancement in the areas of advanced electronics and high-power devices. However, simultaneously achieving high thermal conductivity and mechanical strength for a single material remains a challenge. Herein, we report a new strategy for preparing mechanically strong and thermally conductive composite films by combining aramid nanofibers (ANFs) with graphene oxide (GO) and edge-hydroxylated boron nitride nanosheet (BNNS-OH) via a vacuum-assisted filtration and hot-pressing technique. The obtained ANF/GO/BNNS film exhibits an ultrahigh in-plane thermal conductivity of 33.4 Wm−1 K−1 at the loading of 10 wt.% GO and 50 wt.% BNNS-OH, which is 2080% higher than that of pure ANF film. The exceptional thermal conductivity results from the biomimetic nacreous “brick-and-mortar” layered structure of the composite film, in which favorable contacting and overlapping between the BNNS-OH and GO is generated, resulting in tightly packed thermal conduction networks. In addition, an outstanding tensile strength of 93.3 MPa is achieved for the composite film, owing to the special biomimetic nacreous structure as well as the strong π−π interactions and extensive hydrogen bonding between the GO and ANFs framework. Meanwhile, the obtained composite film displays excellent thermostability (Td = 555 °C, Tg > 400 °C) and electrical insulation (4.2 × 1014 Ω·cm). We believe that these findings shed some light on the design and fabrication of multifunctional materials for thermal management applications.
Highlights
With the rapid development of advanced electronics to higher voltages, higher frequency, and higher temperature, efficient heat dissipation of devices has become a great challenge [1,2,3,4,5]
A previous report has shown that Kevlar fibers that are exposed to a potassium hydroxide/dimethyl sulfoxide (KOH/Dimethyl sulfoxide (DMSO)) system abstracts the mobile protons from amide groups to generate the negatively charged nitrogen ions [47]
The microstructures, thermal conductivity, mechanical properties, electrical insulation, and thermal stability of the nacre-like composite films are investigated in detail
Summary
With the rapid development of advanced electronics to higher voltages, higher frequency, and higher temperature, efficient heat dissipation of devices has become a great challenge [1,2,3,4,5]. The heat conduction network of the polymer matrix can be well constructed while fillers form a random close-packed structure, the high fillers loading will generally deteriorate the superior mechanical performance of a polymer matrix [32] To address this issue, a solution for the combined use of hybrid fillers is proposed [33,34,35,36,37]. The high electrical conductivity of graphene restricts the application of TMMs. GO sheets, as inorganic heat-dissipating filler are as important as graphene; it is found that the oxygen-containing groups on the surface of GO substantially enlarged the interlayer spacing of GO sheets, but effectively improve the dispersibility in the polymer matrix [43,44]. The low content of GO in the composite film remains low electron transport efficiency, resulting in high electrical insulating properties of composite films
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