Flexible Nanoporous Materials by Matrix Removal from Cylinder-Forming Diblock Copolymers

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Abstract

We describe a straightforward self-assembly route to nanoporous materials derived from a hexagonally-packed cylinder (HEX) morphology of a polyisoprene-block-polylactide (PI-b-PLA) diblock copolymer, by thermal cross-linking of the minority PI domains followed by selective chemical etching of the PLA matrix. The resulting mechanically stable and porous samples defy the expectation that the remaining cylinders cannot yield a robust, integrated material upon matrix removal. Scanning electron microscopy imaging reveals that this unexpected structural integrity stems from the interconnected nanofibrils therein, reflecting topological defects at the grain boundaries of the parent polydomain HEX nanostructure. Hydrodynamic radius-dependent poly(ethylene oxide) (Mn = 0.4-35 kg/mol) permeation behavior through these monoliths directly demonstrated the continuity and size selectivity of the nanoporous material. The ready accessibility of block copolymer HEX morphologies of varied chemistries suggests that this matrix etching strategy will enable the future design of functional, size-selective nanofiltration membrane materials.

Original languageEnglish (US)
Pages (from-to)7587-7594
Number of pages8
JournalNano letters
Volume21
Issue number18
DOIs
StatePublished - Sep 22 2021

Bibliographical note

Funding Information:
This work was funded by National Science Foundation grants DMR-1708874 and DMR-2003668 and start-up funds from the Department of Chemical Engineering & Materials Science and College of Science & Engineering at the University of Minnesota. Synchrotron SAXS patterns were collected at the 12-ID-B beamline of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated by Argonne National Laboratory under contract no. DE-AC02-06CH11357. Portions of this work were carried out at the Characterization Facility at the University of Minnesota, which receives partial support from the NSF through the MRSEC (Award Number DMR-2011401) and the NNCI (Award Number ECCS-2025124) programs. We thank Aaron Lindsay for kindly providing the α-hydroxy-polystyrene (PS-OH) and α-hydroxy-polyisoprene (PI-OH) precusors used in this study.

Publisher Copyright:
© 2021 American Chemical Society.

Keywords

  • block copolymer
  • nanofiltration
  • nanoporous polymer
  • polymer membrane
  • self-assembly

How much support was provided by MRSEC?

  • Shared

PubMed: MeSH publication types

  • Journal Article

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