Furthermore, confocal optical microscopy images of CdS NWBBFs
show that the CdS NWs were also uniformly distributed
within the films.27 As a last example, we have made nanoparticle-
BBFs using 40 nm diameter SiC nanoparticles. Optical
imaging shows individual or small aggregations of SiC nanoparticles
at a distance of hundreds of nanometers to a few micrometers
at an initial solution concentration of 0.1–0.6 wt%. Preliminary
results suggest that the nanoparticles are uniformly distributed
in BBFs and do not form more ordered structures such as onedimensional
chains (of nanoparticles). Bubbles with a size of
>10 inches could be easily blown from high concentration nanoparticle
solutions (e.g. >0.6 wt%), and BBFs containing uniformly
distributed, high density individual nanoparticles are possible by
appropriate functionalization to ensure homogeneous dispersion
in the epoxy matrix. Taken together these results demonstrate
a great materials diversity possible for nanomaterial-BBFs.
In addition, the blown bubble method can be extended to
other polymer systems (versus epoxy). For example, poly(methyl
methacrylate) (PMMA), a photoresist material for UV photolithography
and electron-beam lithography, has been employed
to make bubbles embedded with SiNWs or MWNTs, and these
BBFs have been directly processed by photolithography to
pattern nanoelectronic devices.46
2.5 BBF transfer and scale up
Another unique key feature of the BBF approach is that BBFs
with aligned nanostructures can be transferred to a broad range