Automated Platform for Investigating Aligned Carbon Nanotube Films

The one-dimensional nature of single-wall carbon nanotubes (SWCNTs) creates highly directional properties. Utilizing this anisotropy for optoelectronic devices requires researchers to macroscopically align SWCNT ensembles. Recently, surfactant-dispersed SWCNTs were aligned using a manually operated, slow-filtration technique. Building off this method, we present in this work a new platform for reproducibly forming multiple aligned SWCNT films simultaneously. Our parallel filtration setup uses machine vision with pressure feedback control to produce aligned SWCNT films with areas ranging from 2.5 to 9.6 cm². SWCNT alignment is then determined by polarized optical measurements, such as linear dichroism and Raman spectroscopy. The ability to reproducibly create aligned films enables us to investigate parameters contributing to SWCNT alignment. Specifically, we show that for certain filtration conditions, meniscus pinning produces a spherulite pattern. Additionally, we tune the ionic strength across four orders of magnitude to show the effects of the inter-nanotube electrostatic environment on alignment. These results lead us to a deeper understanding of the physics behind SWCNT directional control.