When it comes to thermal insulation, a layperson usually thinks of a polymer. Examples of polymer materials manufactured for trapping heat includes a Styrofoam coffee cup or a silicon oven mitt.
Engineers from the Massachusetts Institute of Technology have revolutionized the original function of a standard polymer insulator. They were able to design thin polymer films that allow heat to pass through. Their results showed that the films thinner than plastic wraps have better heat conductivity compared to other metals. This includes steel and ceramic.
This innovation may serve as the catalyst in applications involving polymer insulators as substitute to conventional metal heat conductors. Their properties of being flexible, corrosion-resistant, and lightweight allows them for possible technological applications in heat dissipating materials in cellphones and laptops as well as cooling elements in cars and refrigerators.
"We think this result is a step to stimulate the field," says Gang Chen, the Carl Richard Soderberg Professor of Power Engineering at MIT, and a senior co-author on the paper. "Our bigger vision is, these properties of polymers can create new applications and perhaps new industries, and may replace metals as heat exchangers."
The team also includes lead author Yanfei Xu, along with Daniel Kraemer, Bai Song, Jiawei Zhou, James Loomis, Jianjian Wang, Migda Li, Hadi Ghasemi, Xiaopeng Huang, and Xiaobo Li from MIT, and Zhang Jiang of Argonne National Laboratory.
Their previous study published in Nature Nanotechnology in 2010 regarding the design of thin polyethylene fibers that were as conductive as most metals and were 300 times more thermally conductive than normal polyethylene. This attracted the attention of different manufacturing companies.
The researchers came to conclude that they need to fabricate ultrathin fibers in order for these polymer conductors to work for any of these applications.
"At that time we said, rather than a single fiber, we can try to make a sheet," Chen says. "It turns out it was a very arduous process."
"The researchers not only had to come up with a way to fabricate heat-conducting sheets of polymer, but they also had to custom-build an apparatus to test the material's heat conduction, as well as develop computer codes to analyze images of the material's microscopic structures," according to Nature Communications.
