  Over the past decade, substantial progress has been made in the chemical
processing (chiral enrichment, length sorting, handedness selectivity, and
filling substance) of single-wall carbon nanotubes (SWCNTs). Recently, it was
shown that large, horizontally-aligned films can be created out of
post-processed SWCNT solutions. Here, we use machine-vision automation and
parallelization to simultaneously produce globally-aligned SWCNT films using
pressure-driven filtration. Feedback control enables filtration to occur with a
constant flow rate that not only improves the nematic ordering of the SWCNT
films, but also provides the ability to align a wide range of SWCNT types and
on a variety of nanoporous membranes using the same filtration parameters.
Using polarized optical spectroscopic techniques, we show that meniscus combing
produces a two-dimensional radial SWCNT alignment on one side of the film.
After we flatten the meniscus through silanation, spatially-resolved nematicity
maps on both sides of the SWCNT film reveal global alignment across the entire
structure. From experiments changing ionic strength and membrane tribocharging,
we provide evidence that the SWCNT alignment mechanism stems from an interplay
of intertube interactions and ordered membrane charging. This work opens up the
possibility of creating globally-aligned SWCNT film structures for a
new-generation of nanotube electronics and optical control elements.
