Transcript CHE5843 Spring 2003 - University of Oklahoma

CHE5480 Summer 2005
Dendrimers and
Nanofluidics
Nanostructured Materials:
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Carbon nanotubes
Aerogels
Zeolites
Dendrimers
Self-assembled
monolayers
Nanoparticles
Nanowires
NEMS, etc.
Example of Nanostructures:
Starburst Dendrimers
What is a dendrimer?
Branched polymers
(dendron = tree in Greek)
Functionality = 3 (Nitrogen)
Generations of Dendrimers
2nd
gen.
4th
gen.
5th
gen.
PAMAM Dendrimer
(polyamidoamine)
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Alternating
(B)-AB-AB-AB-...
 Ethylenediamine (B)
 H2N-C-C-NH2
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Methylacrylate (A)
C=C-CO-OCH3
PAMAM Moieties:
Diamine
Acrylat
e
NH3 or
Diamine
Size of PAMAM Dendrimers
(1 nm = 10 Angstroms)
Generation
M.W.
Angstrom (dia.)
End Gps
Equivalent Sizes with Cells:
Applications of Dendrimers
Gas and chemical sensors
 Catalysts
 Drug delivery and gene therapy
 Surface modifiers (tribology, and
information storage)
 Bio compatible materials
 Electronic devices and antennae
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Nanofluidics:
Flows in channels of nanometer dimension
Nanofluidics :Examples of MEMS & NEMS:
(Micro- & Nano-electromechanical systems)
Lieber (Harvard)
(“Laboratory-on-a chip”)
Lieber (Harvard)
MEMS
Flow behavior in nanofluidics:
Flow behavior in nanofluidics: (2)
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1.
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4.
5.
LOCOMOTION?
difficult to make fluid flow in small channels.
Driving forces:
Pressure
Surface-capillary force
Electric (electroosmotic, electrophoretic,
electrohydrodynamic, electrowetting), and
magnetic (magnetohydrodynamic)
Sound—acoustic
Centrifuge (rotation)
Making Circuitry by
Nanofluidics:
(Lieber, Harvard)
Purpose: using viscous flow in nanochannels.
to orient and assemble nanowires (to make
logical circuitries).
Note: at nanoscale, the surface effects are large
(due to large surface-to-volume ratio). Thus
viscous forces dominate in the flow.
(1) Make a mold of channels (PDMS-polydimethylsiloxane).
(2) Disperse nanowires (GaP, InP, Si) in ethanol, the carrier
solvent. (3) Flow the suspension through the nanochannels.
SEM images of aligned nanowires.
Charles Lieber (Harvard)--2
SEM:
bar = 2 μm
bar = 50 μm
Nanocircuitries :Examples of NEMS
Lieber (Harvard)
hydrophobic surfaces
OTS
Harvard
What happens to the flow when
the interface is hydrophobic? --Slip
2002 Phys.
Fluids
Velocity at wall is 10% of the center (NOT zero,
i.e. Slip). This increases the total volumetric
On what theories to use for nanoscale flows?
2. Nanostructured materials:
Gas adsorption in dendrimers
Dendrimer: PAMAM
2. Nanostructured materials:
Gas adsorption in dendrimers