THERMAL FIELD-FLOW FRACTIONATION APPLICATIONS (Thermal FFF)
Thermal FFF is suitable to separate polymers, gels and
nanoparticles. Because the Thermal FFF channel has no stationary phase or any packing inside, the complete sample is eluted from the Thermal FFF
channel and no loss of material due to shear forces or filtering effects of
a stationary phase is caused.
Polymer Characterization
One application which shows the advantages of Thermal FFF is the separation
of polystyrene polymers. It shows that In Thermal FFF smaller polymers can
also be separated with comparable efficiency than in GPC. But also the high
resolution of Thermal FFF for the higher molar mass polymers can be seen.
The separation of the 900 kDa and 1,200 kDa PS shows this high separation
power of Thermal FFF. On top of that, for molecular weights
higher than 1,200 kDa, Thermal FFF shows an even higher resolution (Solvent
= THF, Detection = ELSD).
Nanoparticle Characterization
Another interesting state-of-the-art and up-to-date application is the
characterization of nanoparticles with Thermal FFF. Especially Carbon
Nanotubes (CNTs) and Carbon Nanoonios (CNOs) are in the center of interest
since a couple of years and can be easily investigated by Thermal FFF
coupled with Light Scattering. Carbon Nanoonions are multi-layered,
concentric large carbon fullerenes. Because of the unique physical and
chemical properties arising from their structure and size, carbon
nanoparticles have potential applications in devices requiring efficient
field emitters, high-strength fibers, strong radiation shields, energy
absorbing materials, nano-scale catalytic beds, efficient gas storage,
nano-circuits, nano-scale transistors, charge storage materials and white
light sources. In addition, they have potential applications as nano-sized,
frictionless bearings, in the construction of nano-mechanical devices,
electromechanical devices and optoelectronic devices. Electron Microscopy
and Atomic Force Microscopy are usually applied to provide visual images of
a selected region of the sample but they are incapable of giving detailed
statistical information about the nano-material. A comprehensive
characterization of carbon nanomaterial is possible if the bulk sample can be separated into narrow sized fractions prior to the subsequent
analyses.
Field-Flow Fractionation in general and Thermal FFF in special has been
proven to be an ideal method to separate and characterize Carbon Nanoonions
and Carbon Nanotubes in aqueous and organic media [1,2]. 1996 Nobel Prize winner
Richard E. Smalley already used Field-Flow Fractionation for the
characterization of a novel type of polymer-wrapped SWNTs, as he stated in
his last patent [3]. Shown here is the separation of Carbon Nanoonions in
non-aqueous solvents using Thermal FFF. The figure shows the result of the
analysis of Carbon Nanoonion clusters in acetonitrile by Thermal FFF coupled
to Light Scattering. The fractionated samples eluting from Thermal FFF have
been checked with scanning electron microscopy (SEM) as shown in the
corresponding picture. The results show that Thermal FFF is easily capable
of separating Carbon Nanoonions according to their size. Also, narrow sized
fractions can be collected during the Thermal FFF separation for further
investigations.
For more information about Thermal FFF contact Postnova Analytics via
telephone, fax, email or visit our homepage
www.postnova.com !
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[1] Chen, B., and Selegue, J.P., Anal. Chem. 2002, 74, 4774-4780
[2] Chen, B., et al. The carbon2002, Beijing, September 2002
[3] Smalley, Richard E.; Rice University Houston, Tx, USA; US Patent
#7,008,563; “Polymer-wrapped single wall carbon nanotubes”, March 7th, 2006.
Flow FFF | Asymmetrical Flow Field Flow Fractionation | Thermal FFF | Sedimentation FFF