Superstable Ultrathin Water Film Confined in a Hydrophilized Carbon Nanotube

Yoko Tomo, Alexandros Askounis, Tatsuya Ikuta, Yasuyuki Takata, Khellil Sefiane, Koji Takahashi

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)
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Abstract

Fluids confined in a nanoscale space behave differently than in the bulk due to strong interactions between fluid molecules and solid atoms. Here, we observed water confined inside "open" hydrophilized carbon nanotubes (CNT), with diameter of tens of nanometers, using transmission electron microscopy (TEM). A 1-7 nm water film adhering to most of the inner wall surface was observed and remained stable in the high vacuum (order of 10(-5) Pa) of the TEM. The superstability of this film was attributed to a combination of curvature, nanoroughness, and confinement resulting in a lower vapor pressure for water and hence inhibiting its vaporization. Occasional, suspended ultrathin water film with thickness of 3-20 nm were found and remained stable inside the CNT. This film thickness is 1 order of magnitude smaller than the critical film thickness (about 40 nm) reported by the Derjaguin-Landau-Verwey-Overbeek theory and previous experimental investigations. The stability of the suspended ultrathin water film is attributed to the additional molecular interactions due to the extended water meniscus, which balances the rest of the disjoining pressures.

Original languageEnglish
Pages (from-to)1869-1874
Number of pages6
JournalNano Letters
Volume18
Issue number3
Early online date9 Feb 2018
DOIs
Publication statusPublished - 14 Mar 2018
Externally publishedYes

Keywords

  • Carbon nanotube
  • water
  • transmission electron microscopy
  • thin liquid film
  • disjoining pressure

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