MIT scientists make heatsink from polythene

Getting beyond the thermal conductivity of copper would currently involve creating a bling heatsinsk using silver or diamonds, but a new discovery at MIT could result in an altered form of polythene being used to conduct heat on future chip coolers.

Yes, we did say polythene; the stuff that you make plastic bags with. Of course, this would be a rubbish material to put next to a hot CPU in its normal state, but the scientists at MIT have found a way of transforming the molecular structure of the material to turn it into an effective heat conductor and electrical insulator.

What’s more, the material only conducts heat in one direction, as opposed to the multi-directional heat conduction that you get from metals. This makes it an ideal material for cooling silicon computer chips, where the main object of the cooling system is to remove heat from the chip and then moving it away via air, water or the extreme cooling material of your choice. Concentrating the flow of heat in one direction will make for a much more efficient cooling system.

The science team was headed by Gang Chen, who is the director of MIT’s Pappalardo Micro and Nano Engineering Laboratories, and the work is outlined in a paper in Nature Nanotechnology this month.

According to MIT, the, "key to the transformation was getting all the polymer molecules to line up the same way, rather than forming a chaotic tangled mass, as they normally do. The team did that by slowly drawing a polyethylene fibre out of a solution, using the finely controllable cantilever of an atomic force microscope, which they also used to measure the properties of the resulting fibre.”

The lead author on the paper, Sheng Shen, explained that there were two stages in the process of creating the new fibres in which the polymer molecules are neatly aligned. “The polymer is initially heated and drawn out, then heated again to stretch it further,” he says. “Once it solidifies at room temperature, you can’t do any large deformation, so we heat it up twice.”

Intel engineer Ravi Prasher is already keen on the idea, saying that “the quality of the work from Prof. Chen’s group has always been phenomenal,” and adding that “this is a very significant finding.” However, he also asked “how scalable is the manufacturing of these fibers? How easy is it to integrate these fibers in real-world applications?”

The answer, according to Chen, is hopefully coming soon. Although the team has so far only succeeded in making individual fibres in the lab, Chen says “we’re hoping that down the road, we can scale up to a macro scale.” This could result in the manufacturing of big sheets of the new material with the same heat conducting properties.