Vu Minh Canh, Kim Il-Ho, Choi Won Kook, Lim Choong-Sun, Islam Md Akhtarul, Kim Sung-Ryong
Department of Polymer Science and Engineering, Korea National University of Transportation, Chungju 27469, Republic of Korea.
Department of Materials Science and Engineering, Korea National University of Transportation, Chungju 27469, Republic of Korea.
ACS Appl Mater Interfaces. 2020 Jun 10;12(23):26413-26423. doi: 10.1021/acsami.0c02427. Epub 2020 May 29.
In modern society, advanced technology has facilitated the emergence of multifunctional appliances, particularly, portable electronic devices, which have been growing rapidly. Therefore, flexible thermally conductive materials with the combination of properties like outstanding thermal conductivity, excellent electrical insulation, mechanical flexibility, and strong flame retardancy, which could be used to efficiently dissipate heat generated from electronic components, are the demand of the day. In this study, graphite fluoride, a derivative of graphene, was exfoliated into graphene fluoride sheets (GFS) via the ball-milling process. Then, a suspension of graphene oxide (GO) and GFSs was vacuum-filtrated to obtain a mixed mass, and subsequently, the mixed mass was subjected to reduction under the action hydrogen iodide at low temperature to transform the GO to reduced graphene oxide (rGO). Finally, a highly flexible and thermally conductive 30-μm thick GFS@rGO hybrid film was prepared, which showed an exceptional in-plane thermal conductivity (212 W·m·K) and an excellent electrical insulating property (a volume resistivity of 1.1 × 10 Ω·cm). The extraordinary in-plane thermal conductivity of the GFS@rGO hybrid films was attributed to the high intrinsic thermal conductivity of the filler components and the highly ordered filler alignment. Additionally, the GFS@rGO films showed a tolerance to bending cycles and high-temperature flame. The tensile strength and Young's modulus of the GFS@rGO films increased with increasing the rGO content and reached a tensile strength of 69.3 MPa and a Young's modulus of 10.2 GPa at 20 wt % rGO. An experiment of exposing the films to high-temperature flame demonstrated that the GFS@rGO films could efficiently prevent fire spreading. The microcombustion calorimetry results indicated that the GFS@rGO had significantly lower heat release rate (HRR) compared to the GO film. The peak HRR of GFS@rGO10 was only 21 W·g at 323 °C, while that of GO was 198 W·g at 159 °C.
在现代社会，先进技术推动了多功能电器的出现，尤其是便携式电子设备，其发展迅速。因此，兼具出色导热性、优异电绝缘性、机械柔韧性和强阻燃性等多种性能组合，可用于有效消散电子元件产生热量的柔性导热材料成为当务之急。在本研究中，石墨烯的衍生物氟化石墨通过球磨工艺被剥离成氟化石墨烯片（GFS）。然后，将氧化石墨烯（GO）和GFS的悬浮液进行真空过滤以获得混合物料，随后，该混合物料在低温下于碘化氢作用下进行还原，将GO转化为还原氧化石墨烯（rGO）。最后，制备出了高度柔性且导热的30μm厚的GFS@rGO复合薄膜，其面内热导率高达212W·m·K，具有优异的电绝缘性能（体积电阻率为1.1×10Ω·cm）。GFS@rGO复合薄膜非凡的面内热导率归因于填料组分的高本征热导率以及填料的高度有序排列。此外，GFS@rGO薄膜表现出对弯曲循环和高温火焰的耐受性。GFS@rGO薄膜的拉伸强度和杨氏模量随rGO含量增加而增大，当rGO含量为20wt%时，拉伸强度达到69.3MPa，杨氏模量达到10.2GPa。将薄膜暴露于高温火焰的实验表明，GFS@rGO薄膜能够有效阻止火势蔓延。微燃烧量热法结果表明，与GO薄膜相比，GFS@rGO的热释放速率（HRR）显著更低。GFS@rGO10在323℃时的峰值HRR仅为21W·g，而GO在159℃时的峰值HRR为198W·g。
