nl9b04764_si_001.pdf (1.53 MB)
Groove-Assisted Global Spontaneous Alignment of Carbon Nanotubes in Vacuum Filtration
journal contribution
posted on 2020-03-04, 19:48 authored by Natsumi Komatsu, Motonori Nakamura, Saunab Ghosh, Daeun Kim, Haoze Chen, Atsuhiro Katagiri, Yohei Yomogida, Weilu Gao, Kazuhiro Yanagi, Junichiro KonoEver
since the discovery of carbon nanotubes (CNTs), it has long
been a challenging goal to create macroscopically ordered assemblies,
or crystals, of CNTs that preserve the one-dimensional quantum properties
of individual CNTs on a macroscopic scale. Recently, a simple and
well-controlled method was reported for producing wafer-scale crystalline
films of highly aligned and densely packed CNTs through spontaneous
global alignment that occurs during vacuum filtration (Nat.
Nanotechnol. 2016, 11, 633).
However, a full understanding of the mechanism of such global alignment
has not been achieved. Here, we report results of a series of systematic
experiments that demonstrate that the CNT alignment direction can
be controlled by the surface morphology of the filter membrane used
in the vacuum filtration process. More specifically, we found that
the direction of parallel grooves pre-existing on the surface of the
filter membrane dictates the direction of the resulting CNT alignment.
Furthermore, we intentionally imprinted periodically spaced parallel
grooves on a filter membrane using a diffraction grating, which successfully
defined the direction of the global alignment of CNTs in a precise
and reproducible manner. These results are promising not only for
developing novel devices based on macroscopically aligned CNTs but
also for understanding the microscopic physical mechanism of the alignment
process.