Scalable fabrication of polymer membranes with vertically aligned 1 nm pores by magnetic field directed self-Assembly

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

Research output: Contribution to journalArticlepeer-review

169 Scopus citations


There is long-standing interest in developing membranes possessing uniform pores with dimensions in the range of 1 nm and physical continuity in the macroscopic transport direction to meet the needs of challenging small molecule and ionic separations. Here we report facile, scalabe fabrication of polymer membranes with vertically (i.e., along the through-plane direction) aligned 1 nm pores by magnetic-field alignment and subsequent cross-linking of a liquid crystalline mesophase. We utilize a wedge-shaped amphiphilic species as the building block of a thermotropic columnar mesophase with 1 nm ionic nanochannels, and leverage the magnetic anisotropy of the amphiphile to control the alignment of these pores with a magnetic field. In situ X-ray scattering and subsequent optical microscopy reveal the formation of highly ordered nanostructured mesophases and cross-linked polymer films with orientational order parameters of ca. 0.95. High-resolution transmission electron microscopy (TEM) imaging provides direct visualization of long-range persistence of vertically aligned, hexagonally packed nanopores in unprecedented detail, demonstrating high-fidelity retention of structure and alignment after photo-cross-linking. Ionic conductivity measurements on the aligned membranes show a remarkable 85-fold enhancement of conductivity over nonaligned samples. These results provide a path to achieving the large area control of morphology and related enhancement of properties required for high-performance membranes and other applications.

Original languageEnglish (US)
Pages (from-to)11977-11986
Number of pages10
JournalACS Nano
Issue number12
StatePublished - Dec 23 2014
Externally publishedYes


  • LC mesophase
  • aligned membranes
  • directed self-Assembly
  • ionic conductivity
  • magnetic alignment
  • nanoporous polymers

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)


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