Researchers create nanoporous polymer membrane that can be used for water purification
With holes 100 nanometers in size, researchers have successfully created an ultrafine porous polymer membrane that could be used to rid water of minute bacteria and virus pathogens.
Thomas Vidil, Ph.D., led this project and worked for two years to create this new membrane material that could have important applications in the purification of water. He worked with Nicholas Hampu, a Department of Chemical Engineering & Materials Science graduate student. Both were advised by Professor Marc Hillmyer.
Creating this polymer meant overcoming many challenges. The membrane had to be highly porous and all the nanopores needed to be uniform in size to be highly efficient. Moreover, the pores had to adopt uninterrupted and bi-continuous paths from the top to the bottom of the membrane. The membrane itself had to be robust enough to force water through using pressure.
The researchers created this new nanoporous membrane by utilizing what is called an order-disorder transition (ODT). Using a block polymer comprising a cross-linkable block and a chemically etchable block, they were able to morph the material from an ordered layered state to a bicontinuous state that could be coated atop a supporting membrane. After curing and etching to remove sacrificial components, the result was the creation of a robust, highly permeable composite membrane that can be used for the ultrafiltration of water.
“It’s like orchestrating different processes at a molecular level,” said Vidil. “This is never an easy task because it requires you to monitor the transition and the reactions while controlling their occurrences. But once you learn how to do it, you have a very powerful and robust system.
“The order disorder transition in block polymers has been known and studied for decades. However, there have been very few studies reporting real applications out of it. Our work is a good illustration that, providing a small additional pinch of creativity and a bit of patience ‘the best wine can come out of an old vessel,’” said Vidil.
Researchers tested the efficacy of the membrane in model filtration studies and showed that it rejected nanoscopic particles with very high efficiency. These studies bode well for real world applications in water filtration.
Hillmyer enjoys engaging in basic fundamental research, where you don’t know what it might lead. “This opens up a new strategy for making other kinds of porous membranes and filters that can be translated into other technologies because of their robustness,” Hillmyer said.
These possibilities include biomedical, separation, catalysis, and energy technologies. Vidil is optimistic that one of those technologies could be the design of new membranes for battery applications.
This research, "Nanoporous Thermosets with Percolating Pores from Block Polymers Chemically Fixed above the Order–Disorder Transition," was published in ACS Central Science. It was funded by a National Science Foundation grant.