Researcher: Sinan Keten, Northwestern University in collaboration with researchers at University of California, Berkeley and Lawrence Berkeley National Laboratory
Scientists at Northwestern University, in partnership with researchers at University of California, Berkeley and Lawrence Berkeley National Laboratory, are designing and synthesizing thin film membranes with unprecedented gas separation capabilities. The thin film membrane may be a breakthrough for clean energy applications such as carbon capture and fuel cell technology.
The thin film membrane has a special nanotube structure that gives scientists a “world of possibilities as to how to separate two different gases, or three different gases, or n different gases,” said Sinan Keten of Northwestern University, principle investigator on the project.
This ability is key for carbon capture technology, where excess CO2, which causes the greenhouse effect, is captured from the atmosphere. The nanoporous membrane can also serve as ion exchange membranes used in fuel cells and energy storage. Other applications include desalinization and possible medical use in artificial kidneys.
The membrane is composed of innovative tunable nanotubes. Tunable nanotubes are tiny tubes that can be adjusted for exact size and chemical composition, so that they have great selectivity in the types of gas molecules they allow through.
Another innovation of the membrane is the ability of the nanotubes to coassemble into block copolymer membranes. A non-scientific way to understand this achievement is to visualize rigatoni noodles spontaneously aligning themselves so that they form a membrane of open tubes – in essence, the ability of basic building blocks to self-assemble into a stable, useful structure.
Challenges in the research exist with stability, design, and understanding of the mechanisms behind coassembly.
“We don’t know how exactly these things self-assemble,” Keten said. “We know they do, but we don’t know it well enough that we can fine tune it a little bit to generate different types of structures, different types of membranes.”
In the long run, the scientists aspire to replicate biological systems, such as the sodium-potassium pump found in cell membranes. Keten notes that such a structure is very complicated, and there is a long way to go before humans can replicate such sophisticated channels.
However, “depending on how you change the chemical structure at this small scale, you could open up a lot of different possibilities,” Keten said.