Multiwalled ice helixes and ice nanotubes
- Jaeil Bai,
- Jun Wang, and
- X. C. Zeng*
- Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE 68588
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Edited by Benjamin Widom, Cornell University, Ithaca, NY, and approved October 31, 2006 (received for review September 25, 2006)
Abstract
We report six phases of high-density nano-ice predicted to form within carbon nanotubes (CNTs) at high pressure. High-density nano-ice self-assembled within smaller-diameter CNT (17,0) exhibits a double-walled helical structure where the outer wall consists of four double-stranded helixes, which resemble a DNA double helix, and the inner wall is a quadruple-stranded helix. Four other double-walled nano-ices, self-assembled respectively in two larger-diameter CNTs (20,0 and 22,0), display tubular structure. Within CNT (24,0), the confined water can freeze spontaneously into a triple-walled helical nano-ice where the outer wall is an 18-stranded helix and the middle and inner walls are hextuple-stranded helixes.
Footnotes
- *To whom correspondence should be addressed. E-mail: xczeng{at}phase2.unl.edu
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Author contributions: J.B. and X.C.Z. designed research; J.B., J.W., and X.C.Z. performed research; J.B., J.W., and X.C.Z. analyzed data; and X.C.Z. wrote the paper.
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The authors declare no conflict of interest.
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This article is a PNAS direct submission.
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This article contains supporting information online at www.pnas.org/cgi/content/full/0608401104/DC1.
- Abbreviations:
- CNT,
- carbon nanotube;
- INT,
- ice nanotube;
- MD,
- molecular dynamics.
- © 2006 by The National Academy of Sciences of the USA
