1 / 40

Self Assembly

Self Assembly. Nano Education Institute 2010. Lithography Deposition Etching Machining. Chemical Self-Assembly. Making Nanostructures: Nanomanufacturing. "Top down" versus " bottom up" methods. First a case you already know: The nanofilm.

keithanderson
Download Presentation

Self Assembly

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Self Assembly Nano Education Institute 2010

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

  3. First a case you already know: The nanofilm 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.... Franklin made this observation, but did not determine the thickness.

  4. Agnes Pockels • The first person to make worthwhile, reproducible measurements on monolayers was Agnes Pockels who lived in Braunschweig, Germany. Agnes Pockels was the original housewife superstar. She performed her first experiments on monolayers in her kitchen in her home, starting in about 1882. She used a tin tray as the water container and a small disk suspended from a balance with a slide weight to measure the surface tension of the water. • By contaminating the water surfaces with different materials, Pockels created monolayers and observed their properties when confining the water surfaces to various areas using waxed tin strips. Pockels observed that the surface tension of a water surface varies with its size and depends on the type of contamination. • She sent an account of her work to Lord Rayleigh, who recommended its publication in the journal Nature. Lord Rayleigh had a similar interest in the science of interfaces and was inspired by Pockels to make his own experiments, from which he concluded that these layers were just a single molecule thick.

  5. hydrophobic end e.g., steric acid pressure Langmuir-BlodgettFilm of an amphiphilic molecule monolayer film water hydrophilic end

  6. multiple dips - multiple layers solid Must control movable barrier to keep constant pressure Langmuir-Blodgett Film Transferred to a Solid Surface liquid

  7. What drives and governs self assembly? As you view the following images you should consider the question:

  8. Tobacco Mosaic Virus wisc.edu nih.gov

  9. Gecko feet

  10. Diatoms sinancanan.net priweb.org

  11. Abalone

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

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

  14. What drives self assembly? • Static assembly (thermodynamic free energy minimum; requires agitation) -- 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)

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

  16. 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)

  17. 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

  18. Nanoparticle Monolayer Formed at a Liquid-Air Interface

  19. Nanoparticle Monolayer Formation toluene Nature Materials MOVIE • Requirements: • rapid evaporation • excess dodecane present • attractive interation to liq-air interface and between particles

  20. ~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

  21. 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

  22. PS/PMMA MW = 42,000 100 cpp TEMPLATE CHARACTERIZATION SAXS SEM Array Period = 24 nm Pore Diameter = 14 nm

  23. UMass-Seagate Improving Order: Guided Assembly in a Trench: Graphioepitaxy side view assemble here top view

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

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

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

  27. 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)

  28. Anodized Aluminum Oxide Templates counter electrode Nanoporous aluminum oxide (AAO) ~ 40 V Aluminum I (oxalic, sulfuric, or phosphoric acid) Anodization Acid Bath Masuda, et al. e.g., • Keller, et al., J. Electrochem. Soc. 100, 411 (1953) • Masuda & Fukuda, Science 268, 1466 (1995)

  29. Al2O3 Al3+ O2- E Al Proposed AAO Growth Mechanism • Density mismatch between Al and Al2O3 • Some Al3+ goes to solution • Mechanical stress yields pore growth in uniform hexagonal array Pore diameters of ~ 10-400 nm possible by choice of anodization conditions Figure adapted from Jessensky, Müller, & Gösele, Appl. Phys. Lett. 72, 1173 (1998)

  30. Improving AAO Order at Surface SiC stamp Aluminum anodize e.g., Masuda et al., Appl. Phys. Lett 71, 2770 (1997); Choi, et al., J. Vac. Sci. Tech. B 21, 763 (2003)

  31. Ni in Anodized Aluminum Oxide Template SEM MFM Nielsch, et al. Appl. Phys. Lett. 79, 1360 (2001).

  32. Molecular Recognition ("lock and key" bonding) hydrogen bonding thymine (T) adenine (A) guanine (G) cytosine (C) biotin-avidin pair (site-specific binding)

  33. Using Synthetic DNA for Designer Structures Designer DNA molecules can be synthesized chemically, and allowed to assemble into a specific configuration of lowest energy. Ned Seeman, NYU

  34. Programmed DNA Folding to Make "DNA Origami" P.W.K. Rothemund, Nature 440, 297 (2006)

  35. Application: RFID Alien Technology Nanoscale Phase Separation IBM "air gap" technology Introducing nanoscale air pockets into the insulating material separating wires on a computer chip -- lowers the capacitance Microfluidic Assembly flow direction Parts, having unique shape, are delivered via fluid flow to mating pockets on an assembly substrate.

  36. Large Scale Self-Assembly (Geological) Giant's Causeway (Northern Ireland) Volcanic basalt cooled rapidly to form these (mostly) hexagonally shaped columns

  37. Additional examples to amplify concepts • balls in a box • magnets • crystallization Forces (non-directional or directional), shape, thermal agitation Nanoscale self assembly • coffee stain • nanoparticle assembly by droplet • others

More Related