Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Dependence of Single-Wall Carbon Nanotubes Alignment on the Filter Membrane Interface in Slow Vacuum Filtration



Jeffrey Fagan, Angela R. Hight Walker, Adam Biacchi, Andrei Kolmakov, Zia Macdermid, William D. Rice, Joshua Walker, Thomas Searles


The recent development of slow vacuum filtration (SVF) technology has shown great promise for reproducibly producing high-quality, large-area aligned films of single-wall carbon nanotubes (SWCNTs) from solution-based nanotube dispersions. In contrast to other SWCNT alignment methods, SVF creates films of high nematic ordering and controllable thickness and can be automated, parallelized, and works with either sorted or mixed SWCNTs. Despite these advantages, the mechanism driving SWCNT alignment self-assembly during SVF remains unclear, a short coming that continues to hinder further optimization of the SVF protocol. In this work, we modify the filter membrane surface to show how the resulting SWCNT nematic order can be significantly enhanced. We show that uni-directional mechanical grooving on filter membranes does not play a significant role in SWCNT alignment, despite the tendency for nanotubes to follow the groove direction. By thermally removing the grooving and treating the membrane surface with different solvents, we find that increased membrane surface roughness, which enhances turbulence right at the SWCNT-membrane interface, increases nanotube alignment. These findings suggest that roughness-enhanced turbulent back flow at the membrane surface, which allows the reorientation of alignment of domains over many agitation cycles, plays a key role in SVF-produced SWCNT alignment.


carbon nanotube, directed assembly, filtration


Fagan, J. , Hight Walker, A. , Biacchi, A. , Kolmakov, A. , Macdermid, Z. , Rice, W. , Walker, J. and Searles, T. (2022), Dependence of Single-Wall Carbon Nanotubes Alignment on the Filter Membrane Interface in Slow Vacuum Filtration, Small, [online],, (Accessed February 26, 2024)
Created January 22, 2022, Updated November 29, 2022