Page 471 - Polymer-based Nanocomposites for Energy and Environmental Applications

424 Polymer-based Nanocomposites for Energy and Environmental Applications

study did not show any loss or crack even at a pressure of 2 bar, whereas high selectivity
was sustained for the filtrationof human rhinovirus type 14 that has a diameter of 30 nm
and is a main pathogen of the common cold in humans. Likewise, the nanoporous mem-
brane revealed excellent resistance to all organic solvents owing to cross-linked PS
matrix during the UV irradiation. This could be employed under harsh filtration con-
ditions such as high temperature and strong acidic (or basic) solution.
Similarly, Thormann et al. [135] have reported a novel preparation procedure to
generate mechanically stabilized nanoporous aluminum oxide membranes for filtra-
tion and biofunctionalization. Nanoporous aluminum oxide membranes were pre-
pared using anodic oxidation with high open porosity. Traditional self-supporting
plus mechanically stabilized nanoporous membranes were synthesized from alumi-
num plates and microimprinted aluminum foils, respectively. The analysis of the
mechanically stabilized membranes was performed using a very thin membrane parts
stabilized by surrounding thick bridges. The minimum thickness of these thin mem-
branes was found 1 mm on both sides with open pores by means of a mean pore size of
the parallel open pores of 185 nm. For cross filtration, the flow rates can be regulated
over a wide range using these two kinds of membrane. The experiments that cannot be
performed with thicker membranes became possible using the mechanically stabilized
membranes, and considerably, higher flow rates were achieved. The biofunc-
tionalization of the pore walls using archaebacterial tetraether lipids was recognized
and proved via aminated semiconductor nanocrystals. The lipid layer deposited on the
pore walls also changed the filtration properties.

15.9 Nanostructured polymer-based membrane

In the recent years, research efforts on developing nanomaterials for the ultrasensitive
detection of biological species have focused owing to their unique optical, electronic,
chemical, and mechanical properties. Materials including metal (gold and silver), car-
bon, and polymers (especially conducting polymers) have been widely used to prepare
nanomaterials such as nanoparticles [136], nanotubes [137], and nanowires [138].
Among nanotubes, CNTs have been of great interest, both from a fundamental
perspective and for potential applications. These open a broad range of applications
including nanoelectronic devices, composites, chemical sensors, and biosensors
owing to their mechanical and unique electronic properties [139].
Nowadays, advances in nanotechnology enhance the R&D in nanostructured
membranes [140].
Various nanomaterials including TiO 2 , SiO 2 , CNTs, zeolite, and metal organic
frameworks (MOF) have been incorporated into polymer matrices to prepare nano-
structured membranes for gas separations [141–145].
Salim and Ho [140] studied the recent developments of the nanostructured
polymer-based membranes, shaped by incorporating nanomaterials and/or porous
membranes using nanoscale pores, for gas separations, RO, ultrafiltration, and other
potential applications. For gas separations, particularly for CO 2 separations from H 2 ,