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CHE5480 Summer 2005

CHE5480 Summer 2005

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CHE5480 Summer 2005

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  1. CHE5480 Summer 2005 Dendrimers and Nanofluidics

  2. Nanostructured Materials: • Carbon nanotubes • Aerogels • Zeolites • Dendrimers • Self-assembled monolayers • Nanoparticles • Nanowires • NEMS, etc.

  3. Example of Nanostructures:Starburst Dendrimers

  4. What is a dendrimer? Branched polymers(dendron = tree in Greek)Functionality= 3 (Nitrogen)

  5. Generations of Dendrimers Your Text Here

  6. Generations of Dendrimers 2nd gen. 5th gen. 4th gen.

  7. PAMAM Dendrimer (polyamidoamine) • Alternating (B)-AB-AB-AB-... • Ethylenediamine (B) • H2N-C-C-NH2 • Methylacrylate (A) • C=C-CO-OCH3

  8. PAMAM Moieties: Diamine Acrylate NH3 or Diamine

  9. Size of PAMAM DendrimersGeneration M.W. Angstrom (dia.) End Gps (1 nm = 10 Angstroms)

  10. Equivalent Sizes with Cells:

  11. 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

  12. Nanofluidics:Flows in channels of nanometer dimension

  13. Nanofluidics :Examples of MEMS & NEMS: (Micro- & Nano-electromechanical systems) Lieber (Harvard)

  14. (“Laboratory-on-a chip”) Lieber (Harvard) MEMS

  15. Flow behavior in nanofluidics:

  16. Flow behavior in nanofluidics: (2) • 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)

  17. 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.

  18. (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.

  19. SEM images of aligned nanowires.Charles Lieber (Harvard)--2 SEM: bar = 2 μm bar = 50 μm

  20. Nanocircuitries :Examples of NEMS Lieber (Harvard)

  21. hydrophobic surfaces OTS Harvard

  22. 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 flow.

  23. On what theories to use for nanoscale flows?

  24. 2. Nanostructured materials: Gas adsorption in dendrimers

  25. Dendrimer: PAMAM

  26. 2. Nanostructured materials: Gas adsorption in dendrimers