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

Thermal interface materials (TIMs) are indispensable materials in thermal management, and Al 2 O 3 -based TIMs are most widely used in thermal managements. Surface modification is an effective method to improve Al 2 O 3 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 Al 2 O 3 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 Al 2 O 3 -MXene-SR TIM with Al 2 O 3 -graphene-SR TIM and Al 2 O 3 -SR TIM under the same Al 2 O 3 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 Al 2 O 3 -MXene-SR TIM is 0.117 MPa, higher than that of the Al 2 O 3 -graphene-SR TIM (0.082 MPa) and the Al 2 O 3 -SR TIM (0.07 MPa). Second, the thermal conductivity of TIMs improves a lot after MXene coating. The thermal conductivity of Al 2 O 3 -MXene-SR TIM is 3.4 W·m −1 ·K −1 , with the matrix/filler mass ratio of 100:1600, which is 30% higher than that of the Al 2 O 3 -SR TIM (2.6 W·m −1 ·K −1 ) and 21% higher than that of Al 2 O 3 -Gr-SR TIM (2.8 W·m −1 ·K −1 ). Whereas the Al 2 O 3 loading keeps the same and the MXene fraction is only about 1.16 vol‰, 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 Al 2 O 3 -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 Al 2 O 3 and SR than graphene, so MXene sheets play the role as a bridge between Al 2 O 3 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.