Deciphering the three-dimensional morphology of free-standing block copolymer thin films by transmission electron microscopy

Frances I. Allen, Peter Ercius, Miguel A. Modestino, Rachel A. Segalman, Nitash P. Balsara, Andrew M. Minor

Research output: Contribution to journalArticlepeer-review

Abstract

Block copolymer thin films with distinct morphologies are prepared by spin casting a nominally lamellar assay of poly(styrene-block-ethylene oxide) from a variety of solvents with and without salt doping. The 3-D morphologies of free-standing thin-film regions, which are obtained by casting directly onto holey substrates, are investigated in detail using various energy-filtering transmission electron microscopy techniques and by electron tomography. Surface characterization is achieved by atomic force microscopy. Our results demonstrate that in order to fully characterize the unique 3-D morphologies of the block copolymer thin films, a multi-method approach is required. When casting from a binary solvent, an unexpected layered honeycomb-type morphology is revealed, which likely results from an expansion of the poly(ethylene oxide) phase. A dramatic effect of selective cation coordination on the morphology of the as-cast block copolymer films is also directly observed.

Original languageEnglish (US)
Pages (from-to)442-450
Number of pages9
JournalMicron
Volume44
Issue number1
DOIs
StatePublished - Jan 2013

Keywords

  • Block copolymer morphology
  • Casting solvent
  • Electron tomography
  • Energy-filtered TEM
  • PS-b-PEO thin films
  • Salt doping

ASJC Scopus subject areas

  • Structural Biology
  • Materials Science(all)
  • Physics and Astronomy(all)
  • Cell Biology

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