(195f) Vertically-Aligned Carbon Nanotube Membranes for Breathable and Protective Fabrics

Vertically-aligned Carbon Nanotube Membranes for Breathable
and Protective Fabrics

N. Bui, S. Kim, E.
Meshot, J.
Pena, S. Guo, K. J. Wu, F. Fornasiero*

Lawrence Livermore National Laboratory, Livermore, CA

P. Gibson

U.S. Army Natick Soldier Research, Development and
Engineering Center, Natick, MA

Membrane
materials with high breathability, high degree of protection from chemical and
biological (CB) agents, and rapid response to CB threats are highly desirable
for protective fabrics. At LLNL, we recently proposed a CB threat responsive
fabric platform based on a carbon nanotube membrane. The membrane consists of an
array of a-few-nm-wide vertically-aligned carbon nanotubes (VACNTs) as through
pores and a flexible, impermeable parylene-N matrix filling the inter-tube
spacing. It promises to provide high water-vapor transport rate and an
effective barrier function to CB agents by best leveraging the outstanding mass
transport properties of narrow CNT channels. Furthermore, this membrane
platform is ideally suited to fundamentally understand the mechanisms of mass transport
through CNT pores.

In
this work, we empirically investigated the transport properties through the
well-aligned, narrow CNT channels at varied length scale. Results showed that these
VACNTs membranes sustained an ultrahigh liquid and gas transport rates when
compared with conventional theory predictions. Also, they performed outstanding
moisture vapor transport rates (> 4000 g.m^-2.day^-1 at
all relative humidities), comparable to or exceeding state-of-the-art breathable
fabrics. Selectivity study showed that these membranes completely excluded 5-7nm-Au
nanoparticles and charged 3-nm dye molecules during dead-end filtration tests. Furthermore,
our membranes demonstrated bioprotection capability through size-exclusion
mechanism when Dengue virus was used as a surrogate for a biological threat
agent. These findings suggest that, with appropriate functionalization at the
CNTs pore entrances, VACNT-polymer composite membranes may provide excellent candidates
for next generation of breathable fabrics with active protection from CB
threats.

This
work was performed under the auspices of the U.S. Department of Energy by
Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.