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128 results on '"Feng, Xunda"'

26. Nanoscale Thickness Control of Nanoporous Films Derived from Directionally Photopolymerized Mesophases.

Author

Imran, Omar Q., Kim, Na Kyung, Bodkin, Lauren N., Dwulet, Gregory E., Feng, Xunda, Kawabata, Kohsuke, Elimelech, Menachem, Gin, Douglas L., and Osuji, Chinedum O.

Subjects
MESOPHASES, PERMEABILITY measurement, REVERSE osmosis, NANOSTRUCTURED materials, THIN films, COMPOSITE membranes (Chemistry), WATER filtration
Abstract

The preparation of thin films of nanostructured functional materials is a critical step in a diverse array of applications ranging from photonics to separation science. New thin‐film fabrication methods are sought to harness the emerging potential of self‐assembled nanostructured materials as next‐generation membranes. Here, the authors show that nanometer‐scale control over the thickness of self‐assembled mesophases can be enacted by directional photopolymerization in the presence of highly photo‐attenuating molecular species. Metrology reveals average film growth rates below ten nanometers per second, indicating that high‐resolution fabrication is possible with this approach. The trends in experimental data are reproduced well in numerical simulations of mean‐field frontal photopolymerization modeled in a highly photo‐attenuating and photo‐bleaching medium. These simulation results connect the experimentally observed nanometer‐scale control of film growth to the strong photo‐attenuating nature of the mesophase, which originates from its high‐aromatic‐ring content. Water permeability measurements conducted on the fabricated thin films show the expected linear scaling of permeability with film thickness. Film permeabilities compare favorably with current state‐of‐the‐art nanofiltration and reverse osmosis membranes, suggesting that the current approach may be utilized to prepare new nanoporous membranes for such applications. [ABSTRACT FROM AUTHOR]

Published
2021
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29. Janus Graft Block Copolymers: Design of a Polymer Architecture for Independently Tuned Nanostructures and Polymer Properties

Author

Guo, Zi‐Hao, primary, Le, An N., additional, Feng, Xunda, additional, Choo, Youngwoo, additional, Liu, Bingqian, additional, Wang, Danyu, additional, Wan, Zhengyi, additional, Gu, Yuwei, additional, Zhao, Julia, additional, Li, Vince, additional, Osuji, Chinedum O., additional, Johnson, Jeremiah A., additional, and Zhong, Mingjiang, additional

Published
2018
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49. Thin Polymer Films with Continuous Vertically Aligned 1 nm Pores Fabricated by Soft Confinement

Author

Feng, Xunda, Nejati, Siamak, Cowan, Matthew G., Tousley, Marissa E., Wiesenauer, Brian R., Noble, Richard D., Elimelech, Menachem, Gin, Douglas L., and Osuji, Chinedum O.

Abstract

Membrane separations are critically important in areas ranging from health care and analytical chemistry to bioprocessing and water purification. An ideal nanoporous membrane would consist of a thin film with physically continuous and vertically aligned nanopores and would display a narrow distribution of pore sizes. However, the current state of the art departs considerably from this ideal and is beset by intrinsic trade-offs between permeability and selectivity. We demonstrate an effective and scalable method to fabricate polymer films with ideal membrane morphologies consisting of submicron thickness films with physically continuous and vertically aligned 1 nm pores. The approach is based on soft confinement to control the orientation of a cross-linkable mesophase in which the pores are produced by self-assembly. The scalability, exceptional ease of fabrication, and potential to create a new class of nanofiltration membranes stand out as compelling aspects.

Published
2016
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