Are There Even Better Performing Thermal Interface Materials available Than Metal?

What could possibly beat it? Many scientists are exploring the use of carbon nanotubes as thermal interface materials. These have been a hot topic for the past couple years, with many graduate students exploring their potential.

Unfortunately, that is all they are today. They are a potential solution which has not been proven as a viable mass-produced thermal interface material. The problem is that in order to seize the magnitude of their conductivity (3000W/mK), the interface must be continuous. These nanotubes are so fine, that they cannot be oriented to stand all the way across the interface unless they are grown on there. This is a time-consuming and tricky process which is near impossible to simulate outside the lab.

Why can't the nanoparticles just be squished together, lowering the thermal resistance, but still capturing the high conductivity of the bulk material? The resistance between the nanoparticles is high enough, even in a silicone suspension, to increase the resistance much higher than a metal TIM.

As far as I am aware, metal thermal interface materials are the highest performing, viable solution available today. If anyone can prove otherwise, please let me know! I look forward to this discussion!

Image courtesy of http://www.epa.gov/epahome/enviroeye/images/nanotubes.jpg