posted on 2023-01-06, 03:03authored byXu-Dong Zhang, Zi-Tong Zhang, Hong-Zhang Wang, Bing-Yang Cao
Thermal interface materials (TIMs), as typical thermal
functional
materials, are highly required to possess both high thermal conductivity
and low Young’s modulus. However, the naturally synchronized
change in the thermal and mechanical properties seriously hinders
the development of high-performance TIMs. To tackle such a dilemma,
a strategy of codoping solid fillers and liquid metal fillers into
polymer substrates is proposed in this study. This strategy includes
a large amount of liquid metals that play the role of thermal paths
and a small amount of uniformly dispersed solid fillers that further
enhance heat conduction. Through the synergistic effect of the liquid
metal and solid fillers, the thermal conductivity can be improved,
and Young’s modulus can be kept small simultaneously. A typical
TIM with a volume of 55% gallium-based liquid metal and 15% copper
particles as fillers has a thermal conductivity of 3.94 W/(m·K)
and a Young’s modulus of 699 kPa, which had the maximum thermomechanical
performance coefficient compared with liquid metal TIMs and solid
filler-doped TIMs. In addition, the thermal conductivity of the solid–liquid
metal codoped TIM increased sharply with an increase of liquid metal
content, and Young’s modulus increased rapidly with an increase
of the volume ratio of copper and polymer. The high–low-temperature
cycling test and large-size light-emitting diode (LED) application
demonstrated that this TIM had stable physical performance. The synergistic
effect of the solid fillers and liquid metal fillers provides a broad
space to solve the classic tradeoff issue of the mechanical and thermal
properties of composites.