  The Langmuir-Blodgett (LB) technique is a powerful, widely used method for
preparing coatings of amphiphilic molecules at air/water interfaces with
thickness control down to a single molecule. Here we report two new LB
techniques designed to create ordered, multifunctional nanoparticle films on
any non-reactive support. The methods utilize Marangoni stresses produced by
surfactants at a fluid/solid/gas interface and self-assembly of nanoparticles
to facilitate rapid creation of dense monolayers of multi-wall carbon nanotubes
(MWCNT), metal-oxide nanoparticles, polymers, and combinations of these
materials in a layer-by-layer configuration. Using the polyolefin separator in
a lithium sulfur (Li-S) electrochemical cell as an example, we illustrate how
the method can be used to create structured membranes for regulating mass and
charge transport. We show that a layered MWCNT/SiO2/MWCNT nanomaterial created
in a clip-like configuration, with gravimetric areal coverage of ~130 mg cm-2
and a thickness of ~3 micron, efficiently adsorbs dissolved lithium polysulfide
(LiPS) species and efficiently reutilize them for improving Li-S battery
performance.
