Ultra‐Flexible, Dielectric, and Thermostable Boron Nitride‐Graphene Fluoride Hybrid Films for Efficient Thermal Management

Abstract

As an important 2D nanomaterial, boron nitride nanosheet (BNNS) has aroused much academic interest due to its high in‐plane thermal conductivity (TC) and good electrical insulation capability. However, the brittleness and low strength of high‐content BNNS films greatly limit its practical application. In the authors’ work, densely layered films containing 2D exfoliated graphene fluoride sheets (GFS) and BNNS with similar phonon vibrational characteristics and intrinsic high TC, are fabricated via vacuum‐assisted filtration (VAF) using cellulose nanofiber (CNF) as the framework. The strong hydrogen bonding between the ternary components and tight “face‐to‐face” contact between the BNNS/GFS interfaces significantly improve the thermal pathway density. Superior in‐plane TC (55.65 W m−1 K−1) of the nanocomposite can be achieved at the 90 wt% BNNS‐GFS loading, a value of 114% greater than a BNNS/CNF counterpart. Additionally, the as‐prepared papery films show tolerance to bending, folding, humid environment, and high‐temperature flame. The newly developed hybrid films are promising for efficient thermal management applications in many electronic devices.

Highly flexible cellulose nanofiber/single-crystal nanodiamond flake heat spreader films for heat dissipation

“…However, with the addition of SCND, the stretching vibration peak of O-H underwent a slight blueshift from 3351 cm À1 of CNF/SCND-0 to 3311 cm À1 of CNF/SCND-7, which indicated the formation of hydrogen bonding between SCND and CNF. 31 Nevertheless, as of the thermal conductivity of the CNF/SCND composite films with those of some reported results; [24][25][26]28,30,31,39,[45][46][47][48][49] (e) setup of the test system for heat dissipation of high-power LED modules; (f) central temperature evolution of the LED chip as a function of running time using various composite films as heat spreaders; and (g) the corresponding IR images.…”

“…[25][26][27] Additionally, preparing composite films with high thermal conductivity requires the addition of high-loading BNNS, which leads to films with poor flexibility. 28 Nanodiamond (ND) is a hydrophilic nanocarbon diamond possessing high thermal conductivity (À2000 W m À1 K À1 ) and excellent electrical insulation (10 7 V cm À1 ) at room temperature, offering great potential applications in the field of thermal management of electrical systems. In addition, due to the high density of ND, high thermal conductivity enhancement can be achieved at lower volume fractions than with BNNS.…”

Emerging Flexible Thermally Conductive Films: Mechanism, Fabrication, Application

“…The used Foygel model is given by Eqs. ( 7 ) and ( 8 ) [ 27 , 175 , 195 ]: where k m , k 0 , V f , V c , L and β are the k of the polymer matrix, k of filler network, volume fraction of fillers, percolation threshold of composites, average length of filler and conductivity exponent dependent on the aspect ratio of fillers, respectively [ 196 ].…”

“…Unfortunately, most of these flexible thermally conductive films cannot be used in common thermal management applications such as TIMs to effectively transfer the heat from heat source to heat sink vertically, because these films usually showed very low through-plane k [ 25 , 26 ]. However, compared to isotropic thermally conductive materials, these thermally conductive films with low thickness, high mechanical strength and excellent flexibility show great potential in thermal management applications such as flexible heat spreader, wearable technologies, personal thermal management, on-skin electronics and energy storage devices, which can effectively transfer the heat from high-temperature positions in the in-plane direction without the compromise of electronics flexibility, while holding back the effect of adjacent components [ 27 , 28 ]. For example, owing to high in-plane k and adequate breathability, graphene/cellulose films can be used as heat management materials in on-skin electronics [ 29 ].…”

Directional fabricating of flexible and compressible cellulose nanofibril composite aerogel with excellent thermal insulation, flame-retardancy and radiative cooling for efficient thermal management

“…As shown in Fig.3c, the FT-IR spectrum of h-BN only exhibits typical in-plane B-N stretching vibration at 1384 cm − 1 and out-of-plane B-N bending vibration at 803 cm − 1 . The FT-IR spectrum of BNNS shows additional O-H stretching vibration at 3466 cm − 1 and B-O stretching vibration at 1049 cm − 1 , which demonstrates the hydroxylation of BNNS(Cheng et al 2022;Liu et al 2021a;Qiu et al 2021). Moreover, the content of each element can be detected in the XPS survey spectrum of BNNS (C: 11.3%, B: 39.7%, N:…”