Achieving Global Alignment of Single-Wall Carbon Nanotube Films through Electrostatic Control

Single-wall carbon nanotubes (SWCNTs), known for their exceptional mechanical, thermal, electrical, and optical properties, present a platform for next generation opto- and thermo-electronics. The difficulty, however, lies in the ability to reproducibly form aligned SWCNT films from aqueous nanotube solutions, which continues to be a significant scientific and technological challenge. Although multiple research groups have achieved high nematic ordering from SWCNT solutions, the mechanism driving this alignment, as well as optimization of it, remains elusive. Here, we use an automated filtration platform and superhydrophobic glass to create globally aligned films from solution-based SWCNTs. We show how SWCNT alignment is impacted by the filtration flow rate and SWCNT electrostatic environment. Additionally, we find that the SWCNT nematicity can be enhanced via buffing of the polymeric membrane coating and hindered by reducing the Debye interaction length of the SWCNTs, both of which show the importance of electrostatics in the alignment mechanism. These results have direct implications for achieving and optimizing the alignment of single- and few- chirality SWCNT films.