- MIT engineers have developed a polymer named polythiophene that conducts heat efficiently.
- It’s flexible, lightweight and 10 times more conductive than conventional polymers.
- It can be directly coated onto silicon wafers and various electronic instruments.
You already know that plastics are perfect insulators – they can effectively trap heat. This property is extremely useful in numerous things such as a coffee cup sleeve, but when it comes to electronic devices, like plastic casings for phones and laptops, they trap heat and makes the device even hotter.
Now MIT engineers have developed a technique that turns plastic insulator into a heat conductor, meaning rather than insulating heat the new material dissipates it. The new polymer is flexible, lightweight and is 10 times more conductive than conventional polymers.
The new material will make it easier to develop electronic devices like solar cells, wearable biosensors and flexible displays. Unlike conventional polymers, which are thermally and electrically insulating, it thermally conducts and eliminates heat efficiently.
MIT engineers believe that this material could also be used in complex thermal management applications, including organic electronics, optoelectronics and self-cooling alternatives.
How It’s Made?
A polymer is a large molecule composed of several repeated subunits (monomers linked end to end). So far, developing polymers has been limited either by strong intermolecular interaction (transferring photon between polymer chains) or strong intramolecular interaction (transferring photon along polymer chains).
Now engineers have tried to achieve both interactions simultaneously. They came up with a technique that allows heat to transfer between- as well as along-polymer chains. They developed a conjugated polymer, called polythiophene or poly(3-hexylthiophene), that has high thermal conductivity.
It is made through bottom-up oxidative chemical vapor deposition, while utilizing strong p-p stacking non-covalent interaction between polymer chains and strong C=C covalent bond along the extended chain.
The reaction formed rigid chains of polymer, instead of twisted strands in traditional polymers. They created large-scale prototypes, each measuring 2cm2.
Testing and Results
Credit: Chelsea Turner / MIT
To test the thermal conductivity of prototypes, engineers used a technique known as time-domain thermal reflectance. In this technique, the material is exposed to a laser beam to heat up its surface. Then they analyze temperature drop by measuring reflectance of the material as heat extends to other parts of the material.
The temperature drop shows how fast heat is propagating to other portions, which further allows engineers to calculate the material’s thermal conductivity.
They found that prototypes were uniform and conducting heat at the rate of 2 Watts per meter per Kelvin, which is 10 times higher than that of traditional polymers. Since the polymer is almost isotropic, it conducts heat in all directions at the same rate, raising material’s heat-dissipating capability.
The oxidative chemical vapor deposition process and nondestructive nature of the material enables the formation of high-quality, thermally conductive thin films on numerous substrates, showing its versatility and countless applicability.
The material can be directly coated onto silicon wafers and various electronic instruments. Engineers plan to further work on this project and make it compatible with other products like films for printed circuit boards and casings for batteries.