(???????)Enhanced interfacial heat-transfer of Al2O3-MXene-silicone composite via an electrostatic self-assembly strategy

ZQ Ye and C Ji and T Yu and R Sun and XL Zeng and BY Cao, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, 199, 123430 (2022).

DOI: 10.1016/j.ijheatmasstransfer.2022.123430

Thermal interface materials (TIMs) are indispensable materials in thermal management, and Al2O3-based TIMs are most widely used in thermal managements. Surface modification is an effective method to improve Al2O3 dispersion in matrix, thereby increasing the maximum filler loading. However, traditional surfactants hardly promote the interfacial heat-transfer on the premise of the same filler loading. In this work, we proposed an electrostatic self-assembly strategy to functionalize the surface of Al2O3 particles with MXene sheets to enhance the interfacial heat-transfer between fillers and silicone rubber (SR). To validate the effectiveness of MXene, we compared the Al2O3-MXene-SR TIM with Al2O3-graphene-SR TIM and Al2O3-SR TIM under the same Al2O3 loading in the aspects of mechanical properties and thermal properties. Though MXene could increase the viscosity and hardness, the negative influence of MXene is much weaker than that of graphene. Nevertheless, the positive impact of MXene is more significant. First, it can reinforce the mechanical strength. The experiment showed the breaking tensile strength of the Al2O3-MXene-SR TIM is 0.117 MPa, higher than that of the Al2O3-graphene-SR TIM (0.082 MPa) and the Al2O3-SR TIM (0.07 MPa). Second, the thermal conductivity of TIMs improves a lot after MXene coating. The thermal conductivity of Al2O3-MXene-SR TIM is 3.4 W m(-1).K-1, with the matrix/filler mass ratio of 10 0:160 0, which is 30% higher than that of the Al2O3-SR TIM (2.6 W m(-1).K-) and 21% higher than that of Al2O3-Gr-SR TIM (2.8 W m(-1).K-). Whereas the Al2O3 loading keeps the same and the MXene fraction is only about 1.16 vol parts per thousand , the increment of the thermal conductivity is mostly due to the improvement of interfacial heat-transfer via MXene. The temperature cycling test and aging test implied that the Al2O3- MXene-SR TIM is thermally stable and reliable. The underlying mechanism of the interfacial heat-transfer enhancement was revealed by the analysis of phonon density of states (PDOS) via a molecular dynamics simulation. The PDOS of MXene is more compatible with Al2O3 and SR than graphene, so MXene sheets play the role as a bridge between Al2O3 and SR to improve the interfacial phonon transport. This work provides an effective method to reduce interfacial thermal resistance in TIMs, which could facilitate the development of thermal management materials. (c) 2022 Elsevier Ltd. All rights reserved.

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