Περίληψη:
Aerogels have been defined as solid colloidal or polymeric networks of
nanoparticles that are expanded throughout their entire volume by a gas.
They have high surface areas, low thermal conductivities, low dielectric
constants, and high acoustic attenuation, all of which are very
attractive properties for applications that range from thermal and
acoustic insulation to dielectrics to drug delivery. However, one of the
most important impediments to that potential has been that most efforts
have been concentrated on monolithic aerogels, which are prone to
defects and their production requires long and costly processing. An
alternative approach is to consider manufacturing aerogels in
particulate form. Recognizing that need, the European Commission funded
NanoHybrids, a 3.5 years project under the Horizon 2020 framework with
12 industrial and academic partners aiming at aerogel particles from
bio- and synthetic polymers. Biopolymer aerogels in particulate form
have been reviewed recently. This mini-review focuses on the emerging
field of particulate aerogels from synthetic polymers. That category
includes mostly polyurea aerogels, but also some isolated cases of
polyimide and phenolic resin aerogels. Particulate aerogels covered
include powders, micro granules and spherical millimeter-size beads. For
the benefit of the reader, in addition to the literature, some new
results from our laboratory concerning polyurea particle aerogels are
also included.
