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Self Assembly

Self Assembly. July 9, 2008. Summer 2008 Nanotechnology Institute. Lithography Deposition Etching Machining. Chemical Self-Assembly. Making Nanostructures: Nanomanufacturing. "Top down" versus " bottom up" methods. What drives self assembly?.

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Self Assembly

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  1. Self Assembly July 9, 2008 Summer 2008 Nanotechnology Institute

  2. Lithography • Deposition • Etching • Machining • Chemical • Self-Assembly Making Nanostructures: Nanomanufacturing "Top down" versus "bottom up" methods

  3. What drives self assembly? As you view some of the following images you should consider the question:

  4. Tobacco Mosaic Virus wisc.edu nih.gov

  5. Gecko feet

  6. Diatoms sinancanan.net priweb.org

  7. Abalone

  8. The Cell and Its Hierarchy ebi.ac.uk

  9. Self assembly at all scales? Whitesides et al. Science 295, 2418 (2002);

  10. What drives self assembly? • Static assembly (thermodynamic free energy minimum) -- once formed it is stable • Dynamic assembly (kinetically formed, not necessarily thermodynamic minimum) -- not necessarily stable • Forces of chemical bonding (4) • covalent, ionic, van derWaals, hydrogen • Other forces (magnetic, electrostatic, fluidic, ...) • Polar/Nonpolar (hydrophobicity) • Shape (configurational) • Templates (guided self assembly) • Kinetic conditions (e.g., diffusion limited)

  11. Excerpt from Letter of Benjamin Franklin to William Brownrigg (Nov. 7, 1773) ...At length being at Clapham, where there is, on the Common, a large Pond ... I fetched out a Cruet of Oil, and dropt a little of it on the Water. I saw it spread itself with surprising Swiftness upon the Surface ... the Oil tho' not more than a Tea Spoonful ... which spread amazingly, and extended itself gradually till it reached the Lee Side, making all that Quarter of the Pond, perhaps half an Acre, as smooth as a Looking Glass.... A nanofilm!

  12. hydrophobic end e.g., steric acid pressure LangmuirFilm of an amphiphilic molecule monolayer film water hydrophilic end

  13. multiple dips - multiple layers solid Must control movable barrier to keep constant pressure Langmuir-Blodgett Film liquid

  14. SAM: Self Assembled Monolayer alkanethiol on gold (Au) HS(CH2)nX where X is the end group of the chain –CH3, –OH, or –COOH Longer alkanethiol molecules have greater thermodynamic stability Review article: J.C. Love, et al., Chem. Rev. 2005, 105, 1103 (G. Whitesides group, Chem Dept, Harvard)

  15. SAM: Self Assembled Monolayer molecules from solution solid • Chemisorbed molecules • Stabilized by intermolecular van der Waals interaction

  16. gold NP SAMs on Nanoparticles There are now many configurations and uses of SAMs imperfect packing J.C. Love, et al., Chem. Rev. 2005, 105, 1103

  17. SAMs via Microcontact Printing (silicon rubber) A type of stamping! J.C. Love, et al., Chem. Rev. 2005, 105, 1103

  18. ~10 nm SELF ASSEMBLY with DIBLOCK COPOLYMERS Block “B” Block “A” PS PMMA Scale set by molecular size Ordered Phases 10% A 30% A 50% A 70% A 90% A

  19. Deposition Template Etching Mask Nanoporous Membrane CORE CONCEPT FOR NANOFABRICATION (physical or electrochemical) Remove polymer block within cylinders (expose and develop) Versatile, self-assembling, nanoscale lithographic system

  20. Nanomagnets in a Self-Assembled Polymer Mask nanoporous template 1x1012 magnets/in2 Data Storage... ...and More

  21. Metal Nanorings Ferromagnetic cobalt rings as small as 15 nm OD

  22. Larger Nanorings Holes Rings

  23. Kinetic Self-Assembly - by Breath Figures Polystyrene Film Mohan Srinivasarao, et al. Science 292, 79 (2001).

  24. More Fabrication by Breath Figures a, Breath-figure pattern obtained with pure polystyrene. b, Optical and c, confocal fluorescence microscope images of different areas of a sample obtained from solvent-casting a polystyrene film from chloroform with CdSe nanoparticles. Scale bars: 16 mum. The inset in c shows a fluorescence intensity scan along the line indicated. UMass: Alexander Böker, Yao Lin, Kristen Chiapperini, Reina Horowitz, Mike Thompson, Vincent Carreon, Ting Xu, Clarissa Abetz, Habib Skaff, A. D. Dinsmore, Todd Emrick and Thomas P. Russell, Nature Materials 3, 302 - 306 (2004)

  25. Conjugate molecular pairing "key & lock" biotin-avidin pair (site-specific binding)

  26. Application: RFID tags (radio frequency identification) Alien Technology Microfluidic Assembly An alternative to "pick and place" -- for tiny parts.

  27. Application: RFID tags (radio frequency identification) Alien Technology Microfluidic Assembly An alternative to "pick and place" -- for tiny parts.

  28. Really Large Scale Self-Assembly Giant's Causeway, Northern Ireland

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