Title: Self Assembly
1Self Assembly
- Nanotechnology Institute
- Summer 2009
Mark Tuominen University of Massachusetts
2(No Transcript)
3Overview
- Self assembly defined
- Self assembly as a process
- Self assembly in nature
- Self assembly in nanotechnology
- Modeling self assembly
- Harnessing self assembly
4Self Assembly Defined
- Static assembly (thermodynamic free energy
minimum) -- once formed it is stable - Dynamic assembly (kinetically formed, not
necessarily thermodynamic minimum) -- not
necessarily stable
5Making Nanostructures Nanomanufacturing
- "Top down" versus "bottom up" methods
6Tobacco Mosaic Virus
wisc.edu
nih.gov
7Gecko feet
8Diatoms
sinancanan.net
priweb.org
9Abalone
10The Cell and Its Hierarchy
ebi.ac.uk
11Self assembly at all scales?
Whitesides et al. Science 295, 2418 (2002)
12What drives and governs self assembly?
- 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)
13Excerpt 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!
14Langmuir Film - of an amphiphilic molecule
15Langmuir-Blodgett Film
solid
Must control movable barrier to keep
constant pressure
liquid
16SAM 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)
17SAM Self Assembled Monolayer
Molecules from solution
solid
- Chemisorbed molecules
- Stabilized by intermolecular van der Waals
interaction
18Nanoparticle Monolayer Formation
toluene
Nature Materials MOVIE
- Requirements
- rapid evaporation
- excess dodecane present
- attractive interaction to liquid-air interface
and between particles
19SELF 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
20CORE CONCEPT FOR NANOFABRICATION
(physical or electrochemical)
Remove polymer block within cylinders (expose and
develop)
Versatile, self-assembling, nanoscale
lithographic system
21TEMPLATE CHARACTERIZATION
PS/PMMA - MW 42,000
SEM
SAXS
Array Period 24 nm Pore Diameter 14 nm
22Improving Order Guided Assembly in a Trench
Graphioepitaxy
side view
assemble here
top view
23Nanomagnets in a Self-Assembled Polymer Mask
nanoporous template
1x1012 magnets/in2
Data Storage... ...and More
24Metal Nanorings
Ferromagnetic cobalt rings as small as 15 nm OD
25More 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)
Mohan Srinivasarao, et al. Science 292, 79 (2001).
26Anodized 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)
27Proposed 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)
28Improving 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)
29Ni in Anodized Aluminum Oxide Template
SEM
MFM
Nielsch, et al. Appl. Phys. Lett. 79, 1360 (2001).
30Microfluidic Assembly
flow direction
Parts, having unique shape, are delivered via
fluid flow to mating pockets on an assembly
substrate.
31Molecular Recognition ("lock and key" bonding)
hydrogen bonding
thymine (T) adenine (A) guanine (G)
cytosine (C)
biotin-avidin pair (site-specific binding)
32Using 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 - http//seemanlab4.chem.nyu.edu/
33Programmed DNA Folding to Make "DNA Origami"
P.W.K. Rothemund, Nature 440, 297 (2006)
34Additional examples to amplify concepts
- Balls in a box
- Magnets
- Crystallization
- Coffee stain
- Nanoparticle assembly by droplet
- Forces (non-directional or directional), shape,
thermal agitation - Nanoscale self assembly
35Summary
- Types of self assembly
- Principles of self assembly
- Mathematics of self assembly
- Self Assembly in nature
- Self assembly in nanotechnology
Self assembly is a key function in the process
of life if not the organization of the entire
universe
36Permissions
- Permission to use this presentation granted by
Mark Tuominen - Professor of Physics Co-Director
of the Center for Hierarchical Manufacturing and
MassNanoTech - 411 Hasbrouck Laboratory, Amherst MA 01003
tuominen_at_physics.umass.edu - Phone 413.545.1944 Fax 413.545.1691
- NSF Nanoscale Science and Engineering Conference
Website - http//umassk12.net/nano/materials/web2011/
- Please do not redistribute without permission!