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Self Assembly

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

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Self Assembly

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  1. Self Assembly Nanoscience Education Institute

  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 of an amphiphilic molecule monolayer film water Langmuir-Blodgett Film hydrophilic end

  6. Irving Langmuir Katharine Burr Blodgett The people behind the research • Nobel prize in chemistry for his work in surface chemistry • First woman to earn a PhD in Physics from Cambridge University Performed their research at General Electric in Schenectady, New York

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

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

  9. Tobacco Mosaic Virus wisc.edu nih.gov

  10. Diatoms sinancanan.net priweb.org

  11. Abalone

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

  13. Gecko feet

  14. Scorpion Armor The scorpion a special grooved shield to protect itself against scratches from desert sand. Researchers study this to help develop materials with good erosion resistance for helicopters, pipes, and other applications. Original article: http://dx.doi.org/10.1021/la203942r Publicity: http://www.sciencedaily.com/releases/2012/01/120125101950.htm

  15. Ultra-tough Shrimp Hammer The peacock mantis shrimp feasts on snails, crabs and other mollusks and crustaceans by smashing through their shells with its front hammer-like claws, delivering 500 Newtons of force. This is powerful enough to punch through aquarium glass. Science magazine June 8, 2012 DOI: 10.1126/science.1218764

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

  17. What enables 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)

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

  19. alkanethiol on gold (Au) HS(CH2)nX where X is the end group of the chain –CH3, –OH, or –COOH SAM: Self Assembled Monolayer 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)

  20. 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

  21. Nanoparticle Monolayer Formed at a Liquid-Air Interface

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

  23. ~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

  24. 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

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

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

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

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

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

  30. 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)

  31. 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)

  32. 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)

  33. 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)

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

  35. 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

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

  37. Programmed DNA Folding: Advanced Designs William Shih, Harvard University

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

  39. NEW! Self-Folding Objects https://www.youtube.com/watch?v=NKRWZG67dtQ http://www.prism-magazine.org/jan13/feature_01.cfm

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

  41. Explore concepts of self assembly in the classroom • Balls in a box (best packing) • Straws or toothpicks in a container (lattice and defects) • How shape influences packing density and the symmetry of assembled structures • Objects floating on water (Cheerios and other shapes) • Two-dimensional array of magnets; floating magnets - attractive and repulsive cases • Crystallization - explore how conditions influence size and perfection of crystals Underlying principles: forces (non-directional or directional), shape, thermal agitation

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