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Nanotechnology A big issue in a small world. H.Aourag URMER, University of Tlemcen. Public concern and media hype. 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.

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Nanotechnology a big issue in a small world l.jpg

NanotechnologyA big issue in a small world

H.Aourag

URMER, University of Tlemcen



What is all the fuss about nanotechnology l.jpg
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.


Does nanotechnology address teaching standards l.jpg

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

Does Nanotechnology Address Teaching Standards?


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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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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

< NM  NM  1000’s of NM’s  Million NM’s  Billions of NM’s


Nanomaterials with different atomic arrangements l.jpg
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

Nano polymer composites for lightweight high resistance bumpers

Fuel cells with nano-catalysts and membrane technologies


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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

• Effective 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-controlled 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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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





Thermoelectric nanomaterials l.jpg
Thermoelectric Nanomaterials

Concepts before modeling can begin:

  • ZT = TσS2/κ

    • T = temperature

    • σ = electrical conductivity

    • S = Seebeck constant

  • κ = κph +κel

    • K = sum of lattice and electronic contributions

    • Potential across thermoelectric material

    • Boltzmann transport






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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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1. Davis, H. T., Bodet, J. F., Scriven, L. E., Miller, W. G. Physics of Amphiphilic Layers, 1987, Springer-Verlag, New York

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

2. M. Sprik, U. Rothlisberger and M. L. Klein, Molec. Phys.1999 97:3553. K. Wang, G. Karlsson, M. Almgren and T. Asakawa, J. Phys. Chem. B1999 103:92374. E. Fisicaro, A. Ghiozzi, E. Pelizzetti, G. Viscardi and P. L. Quagliotto, J. Coll. Int. Sci.1996 182:549


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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

    • Can’t 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

    • Can’t simulate equilibrium self-assembly structure at higher concentration


Monte carlo techniques for the simulation of surfactant solutions continued l.jpg
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


Choosing the right model for our simulation purpose lattice coarse grain l.jpg
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

    • It’s 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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Larson’s Lattice Model – representation of the system lattice coarse-grain

  • 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 N×N×N 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


Larson s lattice model interactions between species l.jpg

Square-well potential lattice coarse-grain

A simple 2D lattice with 2 chains, 7 water (grey) and 6 oil (red) molecules

(i, j=water, oil, head, tail)

Larson’s 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


Larson s lattice model typical trial moves l.jpg
Larson’s Lattice Model - typical trial moves lattice coarse-grain

  • 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


Larson s lattice model simulation process l.jpg

A simple 2D lattice with 2 chains, 7 water (grey) and 6 oil (red) molecules

Larson’s 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 (red) molecules

  • 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 Larson’s 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 (red) molecules

  • 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


Verification of our lattice simulation program compare with larson s simulation results l.jpg
Verification of our lattice simulation program – compare with Larson’s simulation results

  • Ternary phase diagram of H4T4 surfactant in water and oil by Larson’s 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


Simulation results from our simulation program l.jpg
Simulation results from our simulation program with Larson’s simulation results

  • 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


Simulation results from our simulation program continued l.jpg
Simulation results from our simulation program with Larson’s simulation results(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 Materials1999 11: 579


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Motivations to study the textured walls wall textures on the self-assembly structure

  • 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


Simulation results without walls and with flat walls l.jpg

The nano-structures prepared by the evaporation-induced dip-coating process

Self-assembly structure with hydrophobic (left) and hydrophilic (right) walls, according to oil density

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 = 10.7σ , unit cell parameter = 12.4σ

  • 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


Wave patterned wall texture applied in the simulation l.jpg
Wave-patterned wall texture applied in the simulation dip-coating process

  • 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


Lattice monte carlo simulation results for the hydrophilic textured walls l.jpg
Lattice Monte Carlo simulation results for the hydrophilic textured walls

  • Simulation results of 30x30x30 and 30x30x40 simulation box, wave amplitude = 1

  • Surface pattern doesn’t 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


Lattice monte carlo simulation results for the hydrophilic textured walls continued l.jpg
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


Lattice monte carlo simulation results for the textured walls l.jpg
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


Conclusions l.jpg
Conclusions walls

  • 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 > 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


References l.jpg
References walls

  • http://shasta.mpi-stuttgart.mpg.de/research/bionano/bionano/modeling%20and%20simulation%20of%20bio-nano-materials.htm

  • http://www.foresight.org/Conferences/MNT6/Papers/Cagin3/

  • http://www.humphrey.id.au/papers/ITC2004.pdf

  • http://www.engr.uky.edu/%7Emenguc/NECP_Sems/

  • http://pubs.acs.org/cgi-bin/article.cgi/nalefd/2003/3/i04/pdf/nl025967a.pdf

  • http://www.foresight.org/Conferences/MNT6/Papers/Cagin3/

  • http://www.research.ibm.com/topics/popups/serious/nano/html/nanotubes.html


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