APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017;
New Orleans, Louisiana
Session P21: Soft Tribute to John Cahn
2:30 PM–5:30 PM,
Wednesday, March 15, 2017
Room: 281-282
Sponsoring
Units:
DPOLY GSNP
Chair: Kalman Migler, NIST
Abstract ID: BAPS.2017.MAR.P21.3
Abstract: P21.00003 : Liquid Quasicrystals*
3:42 PM–4:18 PM
Preview Abstract
Abstract
Author:
Goran Ungar
(University of Sheffield)
Following the discovery of quasicrystals by Shechtman and Cahn in
1984$^{\mathrm{1}}$, for the following 20 years the new field of QCs was
confined to metal alloys and atomic-scale structures. Then, with the
discovery of a liquid crystal phase possessing dodecagonal QC
symmetry$^{\mathrm{2}}$], research interest has extended from metal alloys
to those where the motifs were no longer single atoms but assemblies of many
molecules. In dendron-based liquid quasicrystals (LQC) between 10-50
molecules form a supramolecular sphere with 10$^{\mathrm{3}}$ --
10$^{\mathrm{4}}$ atoms. In 2007 a 2-d quasiperiodic phase was found in
three-arm star ABC polymers$^{\mathrm{3}}$. In 2012 the first linear diblock
copolymer was reported to form a sphere-based bulk QC phase, similar to that
in dendrimer LQC but on a still larger scale$^{\mathrm{4}}$. In the same
year bulk QC domains were reported in ``hard'' nanoporous silica, produced
however, again from a ``soft'' lyotropic template$^{\mathrm{5}}$. The
symmetry of all confirmed soft QCs so far is 12-fold.
Another important development in soft QCs is the observation of complex QC
approximants in a number of side-branched polyphilic LC honeycombs,
described by multicolour tilings$^{\mathrm{6,7}}$. In fact, recently we
found a genuine dodecagonal QC in such systems, the first example of a 2D
LQC. Furthermore, we succeeded in direct AFM imaging of the \textit{xy} plane of a
dendrimer LQC. The images confirm the ``half-step'' inflation rule, proposed
earlier$^{\mathrm{7}}$ but not confirmed until now.
(1) D. Shechtman, I. Blech, D. Gratias, and J. W. Cahn, \textit{PRL} 1984, \textbf{53},
1951. (2) X.B. Zeng et al, \textit{Nature} 2004, \textbf{428}, 157. (3) K.
Hayashida, et al. \textit{PRL }2007, \textbf{98}, 195502. (4) J. Zhang, F. Bates, \textit{J. Am. Chem. Soc.} 2012,
\textbf{134}, 7636. (5) C. Xiao et al \textit{Nature} 2012, \textbf{487}, 349. (6) B. Chen
et al \textit{Science} 2005, \textbf{307}, 96. (7) X.B. Zeng et al \textit{Science} 2011, \textbf{331},
1302. X.B. Zeng and G. Ungar, \textit{Phil. Mag. }2006 \underline {86} 1093.
*Funding is acknowledged from Leverhulme Trust.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2017.MAR.P21.3