carbon nanomaterials 2013 pt1

8/13/2019 Carbon Nanomaterials 2013 Pt1

1/8

Carbon Nanomaterials Part 1

Dr. Virginia A. DavisMacroscale Assembly and Applications

of Nanomaterials

Spring 2013

Overview

Materials

C60 and other fullerenes

Carbon Nanotubes

Vapor grown carbon fiber, traditional carbon fiber

Graphene

Other Structures

Topics

Types

Properties

Production Techniques

Functionalization

Fullerenes

A new family of carbon discovered in 1985

Closed Convex Carbon cage containing only hexagonal

and pentagonal faces


2/8

Carbon Chemistry

Fullerenes: The angle between a p axis and a C-C bond vector,

is 101.6 (as compared to 90 in planar graphite)

Concavity at each sp carbon center introduces strain but

symmetry distributes the strain evenly across the structure

http://www.chemistry.wustl.edu/~edudev/Fullerene/structure.html

Resonance structure of graphite (stacked planes of carbon)

Sp2 hybridization

H -C - C-H

H H

H H

What we all learned in high school

ALLOTROPES OF CARBON

1 layer graphene

CARBON NANOTUBE/BUCKY BALL MODELS

http://mrsec.wisc.edu/Edetc/pmk/pages/bucky.html

CARBON NANOTUBE CONSTRUCTION

http://www.mrsec.wisc.edu/Edetc/modules/HighSchool/CNT_Vector_Activity/index.html


3/8

C60 Started it All

Discovered by Harold Kroto, James Heath, Sean O'Brien, Robert Curl, and

Richard Smalley in 1985 (Nature 318, 162).

1996 Nobel Prize in Chemistry went to Smalley, Kroto, Curl

If C60 was the size of a soccer ball the soccer ball would be the size of

Neptune

From one of Eulers theorem: spherical surface entirely built up from

pentagons and hexagons must have exactly 12 pentagons

Named Bucky-Ball after American Architect Buckminster Fueller who

designed geodesic domes

Many others C70, C78, C82, C84

12 pentagons arbitrary number of hexagons

http://www.fkf.mpg.de/andersen/fullerene/intro.html

Buckminster Fuller

Time Magazine of January 10, 1964

Apparatus for Discovery C60

http://www.chemistry.wustl.edu/~edudev/Fullerene/discovery.html

Vaporization laser beam strikes a rotating graphite disk plasma of vaporized carbon

atoms.

Pulsed nozzle passes high-density helium over the vaporization zone cooling the

carbon atoms in the plasma and causing them to cluster and be carried through theapparatus

Free expansion of the carbon cluster/gas mixture forms beam

Beam is photoionized with a laser and detected by time of flight mass spectrometry

Timing the laser firing and increasing the time between vaporization and expansion by

adding integration cup resulted in stream resulted in predominantl y C60 with some C70

C60 Potential Applications

Biopharmaceutical ( C

Sixty Inc)

Free radical Sponge

Buckysomes targeted

drug delivery

Pre-clinical trials in progress

Catalysts

Electronics Packaging

Molecular Devices

Polymer Additive

Dye (Blacker than

Carbon Black)

Polymer-Solar Cells: C60

good for charge transfer

ROS = Reactive Oxygen Species

http://www.csixty.com/antioxidant.html


4/8

Nano- To Micro- Scale Properties

Of SWNTS

Electrical conductivity similar to copper (metallic SWNTs)

ballistic conductance, 1 cm at 25 oC (McCuen, 2002)

Thermal conductivity equal or better than that of diamond ~ 3000 W / m K (Hone, 2000)

Low density, small size

density ~ 1.4 g/cm3 , packing ~ 1x1014 SWNT/cm2

Strongest known natural or synthetic material, 100x stronger and

6x lighter than steel

tensile strength at least 37 GPa and strain to failure

at least 6 % (Walters et al. 1999; Yu et al. 2000)

Youngs modulus ~ 0.62 to 1.25 TPa (Gao et al. 1998;

Krishnan et al. 1998; Yu et al. 2000)

CAN THESE PROPERTIES BE REALIZED IN A

MACROSCOPIC SYSTEM???????????

Ways to Think of Nanotubes

Chemist

Single element polymer

C1,000,000 and beyond

Physicist

Single Crystal

Civil Engineer

Beam and Truss

Yakobson and Smalley

Discovered by Iijim a in 1991

Rolled sheet of graphite

Vector Ch defines diameter,chirality and properties

Ballistic conductor n-m = 0

Metal or Very Small band gapsemiconductor: n m integerdivisible by 3

Semiconductor: n - m notdivisible by 3

Zigzag: (0,m) or (n,0)

SINGLE-WALLED CARBON NANOTUBES (SWNTs)

1 2

id a = 1.42 nm

h

h

C a a

C

n m

Dresselhaus and Avouris 2001

zigzag

m = 0

n = 5

0.142 nm


5/8

Discovered by Iijim a in 1991


Vector Ch defines diameter,chirality and properties


Metal or Very Small band gapsemiconductor: n m integerdivisible by 3

Semiconductor: n - m notdivisible by 3


Armch air: (n,m) n = m


1 2

id a = 1.42 nm

h

h

C a a

C

n m

zigzag

armchair

Dresselhaus and Avouris 2001

m = 5

n =5

0.142 nm*

Discovered by Iijima in 1991


Vector Ch defines diameter, chirality

and properties


Metal or Very Small band gap

semiconductor: n m integer divisible

by 3

Semiconductor: n - m not divisible by

3


Armch air: (n,m) n = m

Chiral: (n,m) n m


1 2

i

d a = 1.42 nm

h

h

C a a

C

n m

m = 3

(n,m) : (7,3)

chiral

semiconductor

n = 7

zigzag

armchair

chiralDresselhaus and Avouris 2001

0.142 nm


6/8

Why Bonding (Electronic Structur e) Controls Electrical Properties

http://en.wikipedia.org/wiki/Conduction_band

Valence band: highest range of electron energies occupied at absolute zero

Conduction band: Electron energies at which electrons can accelerate under

applied electron field creating current

Semiconductor: At room temp some electrons can overcome the BAND GAP and

enter conduction band, typically < 3 eV (1 eV = 1.602 x 1019 J )

Metal: conduction and valence bands overlap: Zero band gap

22 April 2005, Guinness World Record

Model of a 5-5 Single Walled Carbon

Nanotube (SWNT)

~65,000 pieces

360 m long, 0.36 m wide (L/D = 1000)

about 100 builders

over 1000 in attendance

Supremely Silly (from Rick Smalley)

RAJAT DUGGAL

(former grad student

now employed by GE)

SWNTs Are Anisotropic

Types of Carbon Nanotubes (CNTs)

BEWARE OF TERMINOLOGY !!!! !!! !!! !!! !!! !

CNT is a general term not a specific entity

Gorillas, chimpanzees, and orangutans are all

apes, but have vastly different characteristics Apples to Oranges Comparisons Abound in

the Peer Reviewed Literature and Popular

Press


7/8

VGCF

Vapor Grown Carbon Fiber (VGCF)

Highly imperfect, not exactly even a carbon nanotube

Much bigger can be > 100 nm diameter

Much easier to disperse than SWNTs or MWNTs

Much lower aspect ratio

Much Cheaper

Worse properties on nanoscale

Sometimes used for method development prior to using

SWNTs, but there are dramatic differences in how they

process

SWNTs

SWNTs molecular perfection

Dimensions, chiralities, defects vary widely

depending on production and purification

processes

All sp2 Hybridized carbons

Ends more reactive due to strain and

endcaps often lost during purification

Molecular perfection makes them hard

to disperse

500 eV/micron van der Waals attraction

Bundle of SWNTs

Spaces between lines

(circle diameter)

~ 1 nm

http://cohesion.rice.edu/naturalsciences/smalley/emplibrary/ropes_1d.jpgDavis et al 2004

5 m

MWNTs/FWNTs/DWNTs

MWNTs Multi-Walled Carbon Nanotubes (MWNTs)

Like nested SWNTs

Easier to disperse

Quality & dimensions vary widely

If 2 cylinders: Double Walled Carbon Nanotubes (DWNTs)

If a few cylinders: FWNTs

1 MWNT


8/8

Courtesy Huina Guo & Dr. Satish Kumar, GaTech

WHAT ARE POTENTIAL

APPLICATIONS OF SWNTS???

WHAT ARE THE

OBSTACLES???

HOW DO YOU SYNTHESIZE

CARBON NANOMATERIALS??

carbon nanomaterials 2013 pt1

Documents