Nanotechnology A big issue in a small world

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Nanotechnology A big issue in a small world

• H.Aourag
• URMER, University of Tlemcen

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Public concern and media hype
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What Is All the Fuss About Nanotechnology?

• Any given search engine will produce 1.6 million
  hits

Nanotechnology is on the way to becoming the
FIRST trillion dollar market
Nanotechnology influences almost every facet of
every day life such as security and medicine.
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Does Nanotechnology Address Teaching Standards?

• Physical science content standards 9-12
• Structure of atoms
• Structure and properties of matter
• Chemical reactions
• Motion and forces
• Conservation of energy and increase in disorder
  (entropy)
• Interactions of energy and matter

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Does Nanotechnology Address Teaching Standards?

• Science and technology standards
• Abilities of technological design
• Understanding about science and technology
• Science in personal and social perspectives
• Personal and community health
• Population growth
• Natural resources
• Environmental quality
• Natural and human-induced hazards
• Science and technology in local, national, and
  global challenges

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Does Nanotechnology Address Teaching Standards?

• History and nature of science standards
• Science as a human endeavor
• Nature of scientific knowledge
• Historical perspective

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Does Nanotechnology Address Teaching Standards?
Nanotechnology Idea Standard it can address
The idea of Nano being small Structure of Atoms
Nanomaterials have a high surface area (nanosensors for toxins) Structure and properties of matter, Personal and Community Health
Synthesis of nanomaterials and support chemistry (space propulsion) Chemical Reactions
Shape Memory Alloys Motion and Forces, Abilities of technological design, Understanding about science and technology
Nanocrystalline Solar Cells Conservation of Energy and increase in disorder (entropy), Interactions of energy and matter, Natural Resources
Nanocoatings resistive to bacteria and pollution Personal and Community Health, Population Growth, Environmental Quality, Natural and human-induced hazards
i
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Does Nanotechnology Address Teaching Standards?
Nanotechnology Idea Standard it can address
Nanomaterials, such as MR (magneto-resistive) fluids in security Science and technology in local, national, and global challenges
Richard P. Feynmans talk, There is plenty of room at the bottom. Feynman had a vision. Science as a human endeavor, Nature of scientific knowledge, Historical perspective
Nanocosmetics and nanoclothing Science as a human endeavor, Science and technology in local, national, and global challenges
Nanotechnology and Science Ethics Science and technology in local, national, and global challenges, Science as a human endeavor, Historical perspective, Natural and human-induced hazards, Population Growth, Personal and Community Health
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What is Nanotechnology?

• It comprises any technological developments on
  the nanometer scale, usually 0.1 to 100 nm.
• One nanometer equals one thousandth of a
  micrometer or one millionth of a millimeter.
• It is also referred as microscopic technology.

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WHAT IS NANOTECHNOLOGY?
The intentional manufacture of large scale
objects whose discrete components are less than
a few hundred nanometers wide. Exploits novel
phenomena and properties at the nanoscale. Nature
employs nanotechnology to build DNA, proteins,
enzymes etc. Nanotechnology Bottom up
approach Traditional technology Top down
approach
It is the ultimate technology.
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What does Nano mean?

• Nano derived from an ancient Greek word
  Nanos meaning DWARF.
• Nano One billionth of something
• A Nanometer One billionth of a meter
• 10 hydrogen atoms shoulder to shoulder
• There are 25 million nms in a single inch.

NATIONAL NANOTECHNOLOGY ACT, October 2003
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VARIOUS MATERIALS IN NANOMETER DIMENSION
lt NM ? NM ? 1000s of NMs ? Million NMs ?
Billions of NMs
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NANOMATERIALS WITH DIFFERENT ATOMIC ARRANGEMENTS
Carbon Nanotube 50,000 times Thinner than Human
hair
Buckyball
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FUTURE AUTOMOBILE
Nano-scale metal oxide ceramic catalysts to
almost eliminate emissions
Carbon nanotubes in windshields frames to make
them strong lightweight
Nano-powders in paints for high gloss durability
Fuel cells with nano-catalysts and membrane
technologies
Nano polymer composites for lightweight high
resistance bumpers
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NANOMATERIALS IN CURRENT CONSUMER PRODUCTS
Cosmetics, sunscreens Containing zinc oxide
and Titanium oxide nanoparticles
Nano polymer Composites for stain Resistant
clothing
Carbon nanotubes
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HEALTH AND MEDICINE
Expanding ability to characterize genetic
makeup will revolutionize the specificity of
diagnostics and therapeutics - Nanodevices
can make gene sequencing more efficient Effe
ctive and less expensive health care using remote
and in-vivo devices
New formulations and routes for drug
delivery, optimal drug usage More durable,
rejection-resistant artificial tissues and
organs Sensors for early detection and
prevention
Nanotube-based biosensor for cancer diagnostics
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HOMELAND SECURITY
Very high sensitivity, low power sensors for
detecting chem/bio/nuclear threats Light
weight military platforms, without sacrificing
functionality, safety and soldier
security - Reduce fuel needs and
logistical requirements Reduce carry-on weight
of soldier gear - Increased functionality
per unit weight
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ESTIMATES OF THE POTENTIAL MARKET SIZE

• Other

• Conservative case

• Materials

• Aerospace

• Chemical Manufacturing

• NSF Estimate

• Pharmaceuticals

• Aggressive case

• Electronics

USD trillions
Nanotechnology related goods and services by
2010-2015
Source National Science Foundation
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SAFETY OF NANOMATERIALS

• Environmental impact
• Absorption through skin
• Respitory ailments
• Evidence that carbon nanotubes cause
• lung infection in mice. Teflon nanoparticles
• smaller than 50 nm cause liver cancer in mice.

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NANOTECHNOLOGY RESEARCH AND COMPUTATION CENTER
(NRCC)WESTERN MICHIGAN UNIVERSITY
Inter Multidisciplinary program Established in
December 2002 www.wmich.edu/nrcc
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AREAS OF RESEARCH

• Molecular Self-Assembly organic, biological,
  and
• composites for molecular recognition, sensors,
  catalysis.
• Sensors chemical, biological, and radiological
  agents
• - biosensors gases (O2, H2).
• Novel nanomaterial synthesis and
  characterization.
• Lab-on-chip and Lab-on-a-CD.
• Novel nanomaterials derived from biological
  molecules
• protein nanotubes, viral scaffolds,
  bacteriophages.
• Quantum mechanical modeling of nanomaterials.
• Electronic structures and properties of
  nanoclusters.
• Fluid dynamics in micro- and nano-channels.
• Molecular electronics.
• Toxicity of nanoparticles.

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Molecular Nanotechnology

• The term nanotechnology is often used
  interchangeably with molecular nanotechnology
  (MNT)
• MNT includes the concept of mechanosynthesis.
• MNT is a technology based on positionally-controll
  ed mechanosynthesis guided by molecular machine
  systems.

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Nanotechnologyin Field of Electronics

• Miniaturization
• Device Density

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History

• Richard Feynman
• 1959, entitled There's Plenty of Room at the
  Bottom
• Manipulate atoms and molecules directly
• 1/10th scale machine to help to develop the next
  generation of 1/100th scale machine, and so
  forth.
• As things get smaller, gravity would become less
  important, surface tension molecule attraction
  would become more important.

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History

• Tokyo Science University professor Norio
  Taniguchi
• 1974 to describe the precision manufacture of
  materials with nanometre tolerances.
• K Eric Drexler
• 1980s the term was reinvented
• 1986 book Engines of Creation The Coming Era of
  Nanotechnology.
• He expanded the term into Nanosystems Molecular
  Machinery, Manufacturing, and Computation

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Nanomaterial and Devices

• Small Scales
• Extreme Properties
• Nanobots

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Self-Assemble

• Nanodevices build themselves from the bottom up.
• Scanning probe microscopy
• Atomic force microscopes
• scanning tunneling microscopes
• scanning the probe over the surface and measuring
  the current, one can thus reconstruct the surface
  structure of the material

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Problems in Nanotechnology

• how to assemble atoms and molecules into smart
  materials and working devices?
• Supramolecular chemistry
• self-assemble into larger structures

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Current Nanotechnology

• Stanford University
• extremely small transistor
• two nanometers wide and regulates electric
  current through a channel that is just one to
  three nanometers long
• ultra-low-power

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• Intel
• processors with features measuring 65 nanometers

Gate oxide less than 3 atomic layers thick
20 nanometer transistor
Atomic structure
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Plasmons

• Waves of electrons traveling along the surface of
  metals
• They have the same frequency and electromagnetic
  field as light.
• Their sub-wavelength require less space.
• With the use of plasmons information can be
  transferred through chips at an incredible speed

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Nanomaterial modeling and simulation types
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What I will cover

• Carbon Nanotubes
• Bio-Nano-Materials
• Thermoelectric Nanomaterials
• What is happening at UK

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Carbon Nanotubes

• What are they?
• Carbon molecules aligned in cylinder formation
• Who discovered them?
• Researchers at NEC in 1991
• What are some of their uses?
• Minuscule wires
• Extremely small devices

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• Potential energy
• Vk Repulsive force
• Va attractive force
• Morse potential equations

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Carbon Nanotubes

• total potential of a system
• Adds the NB contribution
• Force of interaction

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Carbon Nanotubes

• Leonard Jones potential with von der Waals
  interaction
• Geen - Kudo relation

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Bio-Nanomaterials

• What is Bio-Nanomaterials?
• Putting DNA inside of carbon nanotubes
• What can this research give us?
• There are lots of chemical and biological
  applications

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Distances over time

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Van der waals engery

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Radical density profiles

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Thermoelectric Nanomaterials

• Concepts before modeling can begin
• ZT TsS2/?
• T temperature
• s electrical conductivity
• S Seebeck constant
• ? ?ph ?el
• K sum of lattice and electronic contributions
• Potential across thermoelectric material
• Boltzmann transport

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The Modeling equations

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Thermoelectric Nanomaterials
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Thermoelectric Nanomaterials
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Thermoelectric Nanomaterials
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Nanomaterials at UK

• Deformation Mechanisms of Nanostructured
  Materials
• Synthesis of Nanoporous Ceramics by Engineered
  Molecular Assembly
• Carbon Nanotubes
• Optical-based Nano-Manufacturing
• The Grand Quest CMOS High-k Gate Insulators
• Self-assembled metal alloy nanostructures
• Rare-earth Monosulfides From Bulk Samples to
  Nanowires
• Thermionic Emission and Energy Conversion with
  Quantum Wires
• Resonance-Coupled Photoconductive Decay

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Computer Simulation of Fluorinated Surfactants
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Introduction to surfactant and self-assembly

• What is surfactant?
• What is self-assembly?
• Micelles, mesophases

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Introduction to fluorinated surfactants

• Unique properties introduced by the strong
  electronegativity of fluorine and the efficient
  shielding of the carbon atoms by fluorine atoms
• Fluorocarbon chain is stiffer, and favors
  aggregates with low curvature (Fig from 2)
• Advantages over hydrocarbon chains higher
  surface activity , thermal, chemical, and
  biological inertness, gas dissolving capacity,
  higher hydrophobicityand lipophobicity

R-NC5H5Cl- CMC(mM) _at_ 298 K
C12H25- 15.5 3
C8H17- 275 4
C6F13C2H4- 16.2 3
C4F9C2H4- 170 4
2. M. Sprik, U. Rothlisberger and M. L. Klein,
Molec. Phys. 1999 973553. K. Wang, G. Karlsson,
M. Almgren and T. Asakawa, J. Phys. Chem. B 1999
10392374. E. Fisicaro, A. Ghiozzi, E.
Pelizzetti, G. Viscardi and P. L. Quagliotto, J.
Coll. Int. Sci. 1996 182549
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Motivations for the computer simulation of
fluorinated surfactants

• Simulations can be treated as computer
  experiments that serve as adjuncts to theory and
  real experiments
• Experiment is a viable way to study the effect of
  chain stiffness, yet it might be expensive to do
  a systematic study on this topic.
• Computer simulations might help selecting
  surfactants for the right type of mesophase,
  which provides a guideline for experimental
  study.

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Monte Carlo techniques for the simulation of
surfactant solutions

• Off-lattice atomistic simulation
• All atoms (or small group of atoms, e.g. CH2 )
  are explicitly represented
• Most interactions are included, more realistic,
  yet hard to model
• Can simulates molecular trajectories on a
  time-scale of nanoseconds
• Cant simulation the self-assembly phenomena
• Off-lattice coarse-grain
• A number of atoms are grouped together and
  represented in a simplified manner
• Electrostatic and dihedral angle potentials are
  usually absent
• Can simulate process happening on a time-scale of
  microseconds, e.g. micelle formation
• Cant simulate equilibrium self-assembly
  structure at higher concentration

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Monte Carlo techniques for the simulation of
surfactant solutions (continued)

• Lattice coarse-grain
• replacing the continuous space with a discretized
  lattice of suitable geometry
• Electrostatic and intra-molecular potentials are
  absent
• Fast, efficient, can simulate process happening
  on a time-scale of a few hours, e.g. mesophase
  formation
• Based on Flory-Huggins Theory. Proven to be
  successful in polymer science for many years for
  investigating universal properties of single
  chains, polymer layers and solutions and melts
• Utility of the model is limited

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Choosing the right model for our simulation
purpose lattice coarse-grain

• Most time-consuming part in a MC simulation is
  the evaluation of inter and intra-molecular
  potentials after each trial move
• The speed of off-lattice models is limited,
  because
• It has to reevaluate the potential functions
  explicitly when calculate the energy change after
  each move
• The speed of the simulation is determined by the
  complexity of the potential functions
• Off-lattice can at most simulate the formation of
  a few micelles
• Lattice models are fast, because
• Atoms (united atoms) are moving on the lattice,
  intra and inter-molecular distance, bond angles
  are thus discretized
• Its possible to precalculate the potentials
  corresponding to certain distance and angles and
  build look-up tables
• When calculate the energy change, only need to
  look up the tables
• Can simulate the mesophase formation efficiently
• Our targeted system mesophase formation in
  surfactant solutions

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Larsons Lattice Model representation of the
system

• Targeted system a surfactant solution consists
  of NA moles water, NB moles oil and Nc moles
  surfactant molecules, with fixed volume and
  temperature (canonical ensemble)
• Surfactant use HiTj to define a linear
  surfactant consisting of a string of consecutive
  i head units attached to consecutive j tail
  units.
• Whole system resides on an NNN cubic lattice,
  periodic boundary conditions are applied
• Oil and water molecules occupy single sites on
  the lattice, and each amphiphile occupies a
  sequence of adjacent or diagonally adjacent sites
  (equal molar volume for all the species)
• Number of sites occupied by surfactant is,
• The rest of the sites is fully occupied by water
  and oil according to their volume ratio

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Larsons Lattice Model interactions between
species

• Each site interacts only with its 8 nearest, 9
  diagonally nearest, and 9 body-diagonally nearest
  neighbors
• Essentially, a square well potential is applied
• Favorable interactions are set to be -1, while
  unfavorable interactions are 1
• Total energy is pairwise additive

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Larsons Lattice Model - typical trial moves

• Pair interchange 5
• Exchange of positions of two simple molecules
• Chain kink 5
• A surfactant segment exchanges position with its
  neighbor without breaking the surfactant chain
• Chain reptation 5
• One chain end moves to a neighboring site, and
  the rest of that chain slithers a unit to keep
  the chain connectivity
• Chain multiple kink 6
• If a kink move creates a single break in the
  chain, the simple molecule will continue to
  exchange with subsequent beads along the chain
  until beads on the chain are close enough to
  reconnect.

5. R. G. Larson, L.E. Scriven and H. T. Davis, J.
Chem. Phys. ,1985, 83, 2411 6. K.R. Haire, T.J.
Carver, A.H. Windle, Computational and
Theoretical Polymer Science, 2001, 11, 17
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Larsons Lattice Model simulation process

• Initialize the system
• Put the system in a random state
• Make a trial move
• Randomly conduct a trial move according toits
  occurrence ratio
• Calculate the energy change
• Reevaluate the interactions of the moved
  particles with its neighbors and calculate the
  energy change
• Accept the trial move with the Metropolis scheme
• Keep trying the moves until system approach
  equilibrium
• Either monitor the total energy change, or
  monitor the structure formed in the simulation
  box
• Sampling
• Sample a certain property over a certain number
  of configurations

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Simulation of the mesophase formation -
preliminary results

• Simulation procedure
• Start the simulation from a higher temperature
  and equilibrate the system, in order to make the
  system in a athermal state and as random as
  possible
• Anneal the system by decreasing the temperature
  in a small amount after the system reaches
  equilibrium at a higher temperature
• When the temperature is lower than the critical
  temperature, sample the density of a certain
  species
• Preliminary results
• 60vol H4T4 surfactant, 40vol water
• Should form cylindrical structure according to
  Larsons report 7
• The right figures are the same self-assembly
  structure viewed from two different perspectives

3D density contour plot according to the oil
concentration. 60 H4T4 surfactant, 40 water
7. R. G. Larson Chemical Engineering Science,
1994, 49, 17, 2833
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Add the bond overlapping constraint

• Bond overlapping may occurred in the system,
  which is unrealistic
• Simulation results after adding the bond
  overlapping constrain (other conditions are the
  same). Perfect hexagonal close packing
  cylindrical structure is formed.

Two chains overlaps with each other
3D density contour plot according to the oil
concentration. 60 H4T4 surfactant, 40 water
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Verification of our lattice simulation program
compare with Larsons simulation results

• Ternary phase diagram of H4T4 surfactant in water
  and oil by Larsons lattice Monte Carlo
  simulation 8
• 5 data points (volume percentage)
• 40 water, 40 oil, 20 surfactant
• 20 water, 40 oil, 40 surfactant
• 20 water, 45 oil, 35 surfactant
• 60 water, 40 surfactant
• 7.3 water, 32.7 oil, 60 surfactant
• 40 water, 60 surfactant

8. R. G. Larson J. Phys. II France, 1996, 6, 1441
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Simulation results from our simulation program

• 40 water, 40 oil, 20 surfactant - Bicontinuous
  mesophase
• 20 water, 40 oil, 40 surfactant - lamellar
  without holes mesophase
• 20 water, 45 oil, 35 surfactant - lamellar
  with holes mesophase

Left oil concentration profile, Right water
concentration profile
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Simulation results from our simulation program
(continued)

• 60 water, 40 surfactant spherical structure,
  plot according to the surfactant tail density
• 7.3 water, 32.7 oil, 60 surfactant
  intermediate bicontinuous structure (might be
  gyration structure), plot according to the water
  density
• 40 water, 60 surfactant hexagonal close
  packing cylindrical structure, plot according to
  the surfactant tail density

Left oil concentration profile, Right water
concentration profile
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An application of lattice MC simulation the
effect of wall textures on the self-assembly
structure

• Motivation nanostructured materials
• SiO2 source, ethanol, water, catalyst
  surfactants give ordered phases
• Mimic surfactant mesophases (coassembled)
• Calcination gives ordered mesopores

Figures from 9. C.J. Brinker et al. Advanced
Materials 1999 11 579
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Motivations to study the textured walls

• Real substrate surface may not be flat
• For hierarchical materials (macroporous /
  mesoporous), curved surfaces may be present
• Design of nanostructure using surface texturing
  use nano-patterned substrate to control the
  orientation of the self-assembly structure
• Mesopores perpendicular to the substrate is
  desired
• Use the texture on the substrate to make the
  mesopores perpendicular to the substrate

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Simulation results without walls and with flat
walls

• Targeted system
• 60 H4T4 surfactant, 40 water solvent
• The simulation without walls
• Hexagonal close packing cylindrical structures
• From the figure, d spacing 10.7s , unit cell
  parameter 12.4s
• The simulation results with flat walls
• Whether walls are hydrophilic or hydrophobic,
  cylindrical structure are always parallel to the
  wall and sits on the (1, 0, 0) plane

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Wave-patterned wall texture applied in the
simulation

• Walls are treated as a set of block sites, which
  can be neither occupied nor penetrated by any
  molecules
• Interactions between wall site and other
  components in the system are set to 10 or -10,
  to emphasize the wall existence
• The form of the 3D wave function
• Illustration of a discretized wave pattern with
  wall thickness 2 and wave amplitude 2
• Periodic boundary conditions

Wave pattern with wall thickness 2 and wave
amplitude 2
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Lattice Monte Carlo simulation results for the
hydrophilic textured walls

• Simulation results of 30x30x30 and 30x30x40
  simulation box, wave amplitude 1
• Surface pattern doesnt change the structure much
  at lower wall spacing. Walls sit on the (2 1 0)
  plane.
• A little calculation
• How many layer in the horizontal plane
• Number of layers in the vertical plane

Box size 30x30x30, wave amplitude 1, plot
according to the oil density
Box size 30x30x40, wave amplitude 1, plot
according to the oil density
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Lattice Monte Carlo simulation results for the
hydrophilic textured walls (continued)

• Surface pattern changes the self-assembly
  structures at higher wall spacing
• Number of layers in the vertical place
• 30x30x50 box, wall sits on (1, 0, 0) plane
• 30x30x60 box, wave amplitude 1, wall sits on
  (1, 0, 0) plane
• 30x30x60 box, wave amplitude 2, wall sits on
  (2, 1, 0) plane

Box size 30x30x50, wave amplitude 1, plot
according to the oil density
Box size 30x30x60, wave amplitude 1 (left)
and 2(right), plot according to the oil density
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Lattice Monte Carlo simulation results for the
textured walls

• With higher wall spacing, the amount of planar
  defects increases, 2 layers with a different
  orientation formed.
• Same phenomena are not observed in systems with
  hydrophobic walls

Box size 30x30x100, wave amplitude 1, plot
according to the oil density
Box size 30x30x60, wave amplitude 1,
hydrophobic walls, plot according to the oil
density
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Conclusions

• Cylinders always align along diagonal of texture,
  even with small wave amplitude
• For hydrophilic walls, small wall spacing with
  small wave amplitude only distorts structure
• For hydrophilic walls, large wall spacing with
  small wave amplitude promotes (1 0 0) orientation
• For hydrophilic walls, planar defects may be more
  likely if wall spacing gt space needed for of
  layers
• systems with hydrophobic walls may avoid planar
  defects, because
• the deposition of a monolayer of surfactant on
  the wall.
• The chain softness mitigates the pattern

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References

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