MIT Scientists Make a Polyethylene Heatsink

arcticstoat calls our attention to MIT research that has produced a version of polyethylene that can conduct heat away from computer chips. Polyethylene is the most widely used plastic. It's not clear how practical this research is for industrial-scale use, involving as it does an atomic-force microscope. The work is detailed in a paper published in Nature Nanotechnology this month. "The new process causes the polymer to conduct heat very efficiently in just one direction, unlike metals, which conduct equally well in all directions. ... 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 fiber 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 fiber. This fiber was about 300 times more thermally conductive than normal polyethylene along the direction of the individual fibers, says the team’s leader..."

Of course when plastic is exposed to heat...

[Orga]

Of course after being exposed to heat for a couple minutes the material transforms back into a chaotic tangled mass since the polymer molecules are only lined up the same way when at a lower temperature with less molecular volatility.

Re:Article is wrong.

[Xiph1980]

Having a material direct heat in 1 direction doesn't necessarily result in a perpetuum mobile. If said material only conducts heat from point 1 to point 2 if t1 > t2, and doesn't direct any heat in any direction if t1 t2, then it wouldn't break any law of thermodynamics.

Is it electrically conductive?

[Simonetta]

Generally, plastic is not electrically conductive. Which makes it good for mounting electronics. But it is also not heat conductive. Which makes it near worthless for mounting.
    A non-electric conductive, but heat conductive material would be very useful. Especially if it is CHEAP. It could be used to distribute heat in buildings and not just on circuit boards.

AFM is a slow probe

[Heshler]

AFM = Atomic Force Microscope, which is a tiny cantilever that probes a surface down to the atomic scale. I highly doubt this process is high throughput enough to service the electronics industry.

Re:Article is wrong.

[RobVB]

It wouldn't break any laws of thermodynamics. Say it only allows heat transfer from A to B.

If A is warmer than B, energy (heat) will flow from A to B (from warm to cold), decreasing A's temperature while increasing B's. This process decreases energy while increasing entropy, making it perfectly "legal" according to the laws of thermodynamics.

If B is warmer than A, nothing happens, or, perhaps more realistically, the heatsink now acts as a thermal insulator and only allows a very small amount of energy to go from B to A. It would be hard (read: impossible) to make it work perfectly, just like it's impossible to make a perfect thermal insulator.

So maybe something that literally only allows heat flow in one direction is impossible in practice, I don't see why you couldn't make something that has a (much) greater thermal conductivity in one direction than the other. It exists for electronics, why not for heat?