Hydration-responsive folding and unfolding in graphene oxide liquid crystal phases

Fei Guo, Franklin Kim, Tae Hee Han, Vivek B. Shenoy, Jiaxing Huang, Robert H. Hurt*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

181 Scopus citations

Abstract

Graphene oxide is promising as a plate-like giant molecular building block for the assembly of new carbon materials. Its water dispersibility, liquid crystallinity, and ease of reduction offer advantages over other carbon precursors if its fundamental assembly rules can be identified. This article shows that graphene oxide sheets of known lateral dimension form nematic liquid crystal phases with transition points in agreement with the Onsager hard-plate theory. The liquid crystal phases can be systematically ordered into defined supramolecular patterns using surface anchoring, complex fluid flow, and microconfinement. Graphene oxide is seen to exhibit homeotropic surface anchoring at interfaces driven by excluded volume entropy and by adsorption enthalpy associated with its partially hydrophobic basal planes. Surprisingly, some of the surface-ordered graphene oxide phases dry into graphene oxide solids that undergo a dramatic anisotropic swelling upon rehydration to recover their initial size and shape. This behavior is shown to be a unique hydration-responsive folding and unfolding transition. During drying, surface tension forces acting parallel to the layer planes cause a buckling instability that stores elastic energy in accordion-folded structures in the dry solid. Subsequent water infiltration reduces interlayer frictional forces and triggers release of the stored elastic energy in the form of dramatic unidirectional expansion. We explain the folding/unfolding phenomena by quantitative nanomechanics and introduce the potential of liquid crystal-derived graphene oxide phases as new stimuli-response materials.

Original languageEnglish (US)
Pages (from-to)8019-8025
Number of pages7
JournalACS nano
Volume5
Issue number10
DOIs
StatePublished - Oct 25 2011

Keywords

  • assembly
  • folding
  • graphene oxide
  • liquid crystal
  • nematic
  • surface anchoring
  • unfolding

ASJC Scopus subject areas

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

Fingerprint

Dive into the research topics of 'Hydration-responsive folding and unfolding in graphene oxide liquid crystal phases'. Together they form a unique fingerprint.

Cite this