Nanomaterials%20in%20Construction%20and%20Rehabilitation:%20Contributions%20and%20Perspectives%20of%20the%20US%20National%20Science%20Foundation

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Nanomaterials in Construction and
RehabilitationContributions and Perspectives of
the US National Science Foundation

• Jorn Larsen-Basse and Ken P. Chong
• Program Directors, Mechanics and Materials
  Engineering
• National Science Foundation
• Arlington, Virginia, USA
• Jlarsenb_at_nsf.gov kchong_at_nsf.gov
• 2nd International Symposium on Nanotechnology in
  Construction
• Bilbao, Spain, Nov. 13-16, 2005
• Note Opinions expressed are those of the authors
  only NSF takes no position in the matter

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Overview of Presentation

• The National Science Foundation
• Search for the Small
• Technology of the Small
• The Nanotechnology Initiative
• Some Nanotechnology Opportunities Related to
  Infrastructure
• Some Examples of Projects
• Expectations for Future

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NSF

• Conceived by Roosevelt, operational 1950
• Independent US Government agency
• Supports basic research in all areas of science
  and engineering
• Budget now about 6 billion
• Engineering is about 10
• Infrastructure Materials Engineering is 0.08
• Mechanics and Materials Engineering is 0.4

4
NSFs Funding Methods

• Unsolicited proposals researcher-generated
  ideas (from universities, mostly)
• free flowing, or in response to central
  initiatives
• most funds go to the PI-generated ideas most
  new funds are earmarked for initiatives
• Peer review success rate low (10-20)
• Awards - grants to universities for support of
  individual investigators, groups, centers
• Some centers and networked equipment and/or
  computational user facilities awarded in response
  to calls for proposals
• Research community helps define directions
  reviewers, program directors, workshops,
  unsolicited proposals

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Long History of Tools to Search for The Small
Leads to the Present

• 14th century grinding of lenses for spectacles,
  Italy
• 1590 Dutch Janssen brothers make first microscope
• 1667 Robert Hooke publishes Micrographia
• mid-19th century, metallograph (reflected light)
  microstructure
• 1938 Ruska develops electron microscope
  dislocations, precipitates
• 1950 electron microprobe leads to SEM surface
  observations
• 1981 Binnig Rohrer invent STM, Nobel Prize
  1986. (Precursor instrument used at NIST 1965-71
  by Russell Young et al).
• STM leads to AFM high resolution SEM, STEM
• Recent discoveries of new material forms fan the
  fires of investigation
• 1996 Nobel prize for discovery of C60, Buckyball
• 1991 Iijima in Japan discovers carbon nanotube

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Carbon Nanotubes

• SWNTs and MWNTs
• Diameter 1 nm
• Length 100 mm (and larger)
• Perfect hexagonal structure
• In-plane covalent (s) bonds dominates mechanical
  property
• Out-of-plane (p) gas cloud determines electrical
  property

Potential Applications Nano-electronics
Nano-electro-mechanical systems Nano-composites
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Mechanical Properties of Carbon Nanotubes

• Superior Mechanical Properties
• Elastic Modulus 1 TPa
• Yield Strain More than 4
• Buckling Strain 5 (aspect ratio of 1/6)
• Potential Application Nano-composite

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Breaking Strain of Carbon Nanotubes

• Model the breaking strain calculated by molecular
  dynamics as the critical strain for bifurcation
  in the continuum analysis.

• Breaking strain calculated by molecular dynamics
• EZZ 55
• Bifurcation strain predicted by the nanoscale
  continuum theory
• EZZ 52
• Reasonable agreement between the continuum and
  atomistic approaches.
• No additional parameter fitting!

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Properties of Carbon Nanotubes (CNT)
Best available under development
Emerging material, carbon nanotubes
Baseline Material, available today
Single Crystal bulk material (CNT)
1000
500
Specific Modulus GPa/(g/c3)
CNTFRP Composite
Long-term potential of CNT material
200
100
50
CFRP Composite
Aluminum 2219
20
10
0.5
5
0.2
2
20
50
1
10
100
0.1
Specific Strength, GPa/(g/c3)
from NASA-larc
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Technology of The Small has Advanced in Step
with Science

• Transistor 1947, Bardeen Brattain
• Junction transistor 1950, Shockley (the 3 got
  Nobel in 56)
• Integrated Circuit 1958, Kilby (Nobel in 2000)
• Moores law 1964 number of transistors/area
  doubles about every 1.5 years (1971 2,250
  transistors 2003 Itanium 2 chip has 410,000,000
  transistors). Constantly pushing the limits -
  nano is next lithography? quantum dots, quantum
  computing?
• Storage capacity of magnetic hard disk drives has
  followed similar path. First 1956 50 disks, 24
  diameter, flying ht. 20 Micrometers. First 1 Gb
  storage1980,size of refrigerator, weight 550 lbs
  (250 kg). Now 1Gb drives can be the size of a
  US quarter coin. Developments made possible by
  smaller domains, smoother media, lower head
  flying height, thinner overcoats and lubricants
• MEMS
• Nanotechnology

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M. ROCO, 2002
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US Federally Funded Nanotechnology
Initiative(more at www.nano.gov)

• Budgets, in millions 1997 2001
  2005 (request)
• National Science Foundation 65 150
  305
• Defence
  32 125 276
• Energy 7 88 211
• Health, NIH 5
  40 89
• NIST
  4 33 53
• NASA
  3 22 35
• Total
  116 464 982
• Similar activities in many other countries
• NSF funds small grants for exploratory research,
  groups of researchers, large centers, and
  networks of user facilities for nanofabrication
  

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Defining the vision for the second strategic plan
(II) National Nanotechnology Initiative 2004
2004 10-year vision/plan
Energy
Agriculture and Food
Societal Implications 2004
Reports
Government Plan (annual)
Survey manufacturing
Other topical reports on www.nano.gov
2004 Update 10 year vision, and develop
strategic plan
MC Roco, 3/16/05
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NNI Outcomes 2001-05

• 4000 projects at 500 institutions
• 25 or world investment in nano-
• 30,000 papers in 2004 (2x number for Si, 6x
  steel)
• US 875 nanotech companies, 50 small
  businesses, 60 have products, others license
• 60 of nano-patents and 70 of start-up companies
  are in US large of patents for foreign
  companies
• World-wide 20,000 people work on nanotechnology
  (some re-classified, e.g., from catalysts some
  cosmetics, to nano-)

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Infrastructure Outcomes of 2001-2005
NSF RD Networks and User Facilities

• Network for Computational Nanotechnology (NCN)
  7 universities
  (Purdue as the central node)
  Nanoelectronic device
  simulation/modeling
• National Nanotechnology Infrastructure Network
  (NNIN) 13
  universities with user facility Develop
  measuring manuf. tools, including NEPM
  -Education and societal
  implications
• Oklahoma Nano Net (EPSCoR award)
• Centers
• 16 Nanoscale Science and Engineering (NSEC) -
  6 (2001) 2 (2003) 6 (2004) 2 (2005)
• 1 Nanotechnology Center for Learning and
  Teaching (NCLT)
• 6 new Materials Research Science and
  Engineering Centers (MRSEC)

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NNI FY 2006 Budget RequestTotal 1,054 million
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Areas of investment in FY2006(Program Component
Areas)

1. Fundamental Nanoscale Phenomena and Processes
2. Nanomaterials
3. Nanoscale Devices and Systems
4. Instrumentation Research, Metrology, and
   Standards for Nanotechnology
5. Nanomanufacturing
6. Major Research Facilities and Instrumentation
   Acquisition
7. Societal Dimensions

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Construction- and Infrastructure-Related
Opportunities in Nano-

• Most work to date has been in electronic and
  biomedical applications
• Potential construction-related applications
• Smart aggregates and coatings acting as wireless
  sensors and actuators
• Self-healing structural polymers, pavements
  self-assembly
• Large surface/volume ratio gives new
  possibilities
• Ultra-high strength, ultra-high ductility steels,
  polymers and even concrete
• New composite materials photocatalytic coatings
• Plus new tools are giving new understanding of
  basic materials structure-property relations,
  especially needed for cement

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Polymer Nanocomposites NIST
Layered Silicates
Polyurethane
Quantum Dots
ZnO
Polyethylene
SiO2
PMMA
Carbon Nanotubes
Epoxy
TPO
Nanowires
PDMS
Ag
TiO2
Polypropylene
Polystyrene
Nylon

• Flame retardant materials
• Conducting polymers
• Scratch resistant coatings
• Self-healing materials
• Self-disinfecting surfaces

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Nano-Clay Filled Polymers NIST

• Certain types of clay naturally form platelet
  structures
• Thickness just less than 1 nm
• High aspect ratios
• Lengths and widths are 25 to 2000 times the
  thickness
• Gallery spacing between platelets between 1.5 nm
  and 2 nm
• Contain cations for charge balance
• Hold platelets together
• Use of just 1 to 5 by volume can dramatically
  alter material behavior
• Properties related to flammability improved
• Mechanical properties improved
• Improvements often depend on ability to separate
  and disperse platelets
• Organic treatment needs to be thermally stable.

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Some Current Project Areas Supported by the NSF
Mechanics and Materials Programs

• Cement materials science
• Measure progress of hydration by high intensity
  nitrogen ion beams
• Follow strength evolution by X-ray tomography
  plus elastic wave
• Self cleaning photocatalytic coating, field trial
• Composites nanotubes, nanoparticles in various
  matrices
• Multiscale modeling of concrete, composites
• Biosealant for cement, derived from genetically
  engineered bacteria
• Workshop on cellulose nanotubes from wood

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Example Nanoscale alumina (40nm) / PMMA
graduate student - Ben Ash (NSF - Nanoinitiative)

• Order of magnitude increase in ductility
  accompanied by a decrease in Tg, modulus and
  strength

Stronger Interface

• No change in MW, tacticity
• No residual monomer
• NMR results support this result

Weak Interface
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Nanocomposites vs Microncomposites

• Interparticle distance decreases
• Surface area increases
• Interaction zone
• region of altered mobility and chain
  conformation
• region of altered crystallinity
• small molecule migration
• crosslink density
• chemistry

Interaction zones will overlap at low
volume fractions (2 vol)
L. SCHADLER, RPI
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Nanotube Composites Offer Promises and Challenges

• Nanotubes are super strong and also very flexible
  and they have large surface area with strong
  tube-matrix interfaces one could have composites
  with the unusual combination of both high
  stiffness and high ductility because nanocracking
  and crack deflection are possible. Many
  questions remain
• Wetting, adhesion, how measure, how manipulate?
• Stress transfer, how model deformation zone near
  reinforcement
• SWNT, MWNT, ropes, how do they deform?
• Mixing is problem, and eventually quality
  control, mass production, cost, health and many
  other issues have to be dealt with
• So far, most nano-composites have been
  nanoparticle- or nanotube-filled polymers rather
  than true composites

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Vaia, Wagner, Materials Today, Nov. 2004, 32-37
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Vaia, Wagner, Materials Today, Nov. 2004, 32-37
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Metal Oxide Nanoparticles in Coatings

• TiO2 and ZnO used in nanosize forms in sunscreens
• Photoreactive behavior
• Good absorbers of UV light
• Deactivate and destroy
• Bacteria, viruses, fungi
• Organic and inorganic pollutants in air and water
• Cancer cells
• Producing energy via photoelectrochemical cells
• Applications include
• Self-disinfecting surfaces
• Paints and coatings with improved durability
• Indoor air cleaners
• Water treatment
• Mitigation of air-borne biological agents
• Solar cells

If charge carriers get to surface O2-
superoxide OH. hydroxyl radical H2O2
hydrogen peroxide and other activated oxygen
species can be generated. All are capable of
further reaction with organic materials for good
or bad
NIST
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Symbol of Purity The Lotus Leaf
The white lotus, born in the water and grown in
the Water, rises beyond the water and remains
unsoiled By the water (ancient Indian Buddhist
text)
Symbol of Purity
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Nano-raspberries, strongly water repellant
surface, silica spheres bonded to epoxy-based
polymer film (Eindhoven U)
Nano
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Materials Today, March 2005, cover
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Biosealant-producing genetically engineered
microorganism a) the original strain b)
Transformed with plasmid to produce exopolymer
and CaCO3 (Bang)
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Length and time scale of Present day mechanics
years
Engineering Design
Friction Machines, i.e. SFA
minutes
Continuum Models
Proximal Probes, i.e. AFM
millisec
Micro- structural Models
microsec
Atomic Simulations
picosec
Quantum Simulations
femtosec
Courtesy W. Goddard
0.1 nm
1 nm
10 nm
1 mm
meters
1 cm
SFA
AFM
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Modeling and Measuring the Structure and
Properties of Cement-Based Materials
http//ciks.cbt.nist.gov/monogr
aph/
nm
?m
mm
REAL
MODEL
Over 10,000 users from 83 countries per month
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DISCUSSIONS OF COMMON MODELING METHODS

• FIRST PRINCIPLE CALCULATIONS - TO SOLVE
  SCHRODINGERS EQ. AB INITIO, e.g. HATREE- FOCK
  APPROX., DENSITY FUNCTIONAL THEORY,
• - COMPUTIONAL INTENSIVE, O(N4)
• - UP TO 3000 ATOMS
• MOLECULAR DYNAMICS MD - DETERMINISTIC, e.g. W/
  LENNARD JONES POTENTIAL
• - MILLIONS TIMESTEPS OF INTEGRATION TEDIOUS
• - UP TO BILLION ATOMS FOR NANO-SECONDS
• COMBINED MD CONTINUUM MECHANICS CM, e.g.
  MAAD LSU BRIDGING SCALE
• - PROMISING...

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Summary and Outlook

• While nanotechnology has been the subject of much
  hype there are many developments on the horizon
  which can benefit the infrastructure and
  construction fields
• Materials
• Coatings
• Sensors
• Durability
• New designs and structures taking advantage of
  much stronger materials, ductile concrete (?) and
  other advances
• Many advances depend on serious engineering of
  lab-demonstrated concepts, from the pretty
  picture to the useful product or structure

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   Figure 4 Structure and pivot motion of the
trimers. (a) Structure of trimers 2 and 3. A
sequence of STM images (b-e) acquired
approximately 1 min apart during annealing at
225    C show the pivoting motion of 2 (both
circled molecules) and lack of translation in b-e
of any molecules. These images were taken from a
much longer sequence at the same temperature, a
part of which can be found on http//tourserver.ri
ce.edu/movies/ (Vb -0.7 V, It 200 pA image
size is 34 27 nm2). Monatomic step edges in
these images are lined with clustered molecules.
(f) A summary of the two methods of motion for
the different structures showing that nanocar 1
consecutively pivots and then translates
perpendicular to its axles, whereas trimer 2
pivots but does not translate on the surface. For
clarity, both structures are drawn devoid of the
alkoxy units.
Shirai et al, Nanoletters Sept. 05 Nanocar