overview for carbon nanotubes

1. CARBON
NANOTUBES
PRESENTED BY :- JEMIN MANGUKIYA
(19BME045)

2.  WHAT ARE CNTs ?
• CARBON NANOTUBES (CNTS) ARE CYLINDRICAL MOLECULES THAT
CONSIST OF ROLLED-UP SHEETS OF SINGLE-LAYER CARBON
ATOMS
• CARBON NANOTUBES (CNTS) ARE AN ALLOTROPE OF CARBON.
• THEY ARE CHEMICALLY BONDED WITH SP2 BONDS, AN EXTREMELY
STRONG FORM OF MOLECULAR INTERACTION.
• NANOTUBES ARE MEMBERS OF THE FULLERENE STRUCTURAL
FAMILY, WHICH ALSO INCLUDES BUCKYBALLS.
• WHEREAS BUCKYBALLS ARE SPHERICAL IN SHAPE, A NANOTUBE
IS CYLINDRICAL, WITH AT LEAST ONE END TYPICALLY CAPPED
WITH A HEMISPHERE OF THE BUCKYBALL STRUCTURE

3. • A CARBON NANOTUBE HAS A HONEYCOMB LATTICE ROLLED INTO CYLINDER .
• DEPENDING UPON THE STRUCTURE THERE ARE TWO TYPES OF CNTs.
 A FEW CONCENTRIC CYLINDERS WITH THE REGULAR PERIODIC INTERLAYER
SPACING LOCATE AROUND ORDINARY CENTRAL HOLLOW AND MADE MWCNTs
(MULTI WALLED CARBON NANOTUBES).
• DEPENDING ON THE NUMBER OF LAYERS, THE INNER DIAMETER OF MWCNTs
DIVERGES FROM 0.4 NM UP TO A FEW NANOMETERS AND OUTER DIAMETER
VARIES CHARACTERISTICALLY FROM 2 NM UP TO 20 TO 30 NM.
• MOREOVER THE ENDS ARE CAPPED WITH DOME SHAPED PENTAGONAL RINGS.
 ON OTHER HAND, SWCNT (SINGLE WALLED CARBON NANOTUBES) DIAMETERS
DIFFER FROM 0.4 TO 2 TO 3 NM, AND THEIR LENGTH IS TYPICALLY OF THE
MICROMETER RANGE.
• SWCNTS USUALLY CAN COME TOGETHER AND FORM BUNDLES (ROPES). IN A
BUNDLE STRUCTURE, SWCNTS ARE HEXAGONALLY ORGANIZED TO FORM A
CRYSTAL-LIKE CONSTRUCTION
STRUCTURE

4. FIGURE :-
1. SINGLE WALL CNT
2. MULTIWALL CNT

5. ZIGZAG CONFIGURATION
ARMCHAIR CONFIGURATION

6. • THERE ARE SEVERAL TECHNIQUES THAT HAVE BEEN DEVELOPED FOR
FABRICATING CNT STRUCTURES WHICH MAINLY INVOLVE GAS PHASE PROCESSES.
COMMONLY, THREE PROCEDURES ARE BEING USED FOR PRODUCING CNTS:
(1) THE CHEMICAL VAPOR DEPOSITION (CVD) TECHNIQUE
(2) THE LASER-ABLATION TECHNIQUE , AND
(3) THE CARBON ARC-DISCHARGE TECHNIQUE .
(4) HIGH PRESSURE CARBON MONOXIDE DISPROPORTIONATION(HIPCO)
• HIGH TEMPERATURE PREPARATION TECHNIQUES FOR EXAMPLE LASER ABLATION
OR ARC DISCHARGE WERE FIRST USED TO SYNTHESIZE CNTS, BUT CURRENTLY,
THESE TECHNIQUES HAVE BEEN SUBSTITUTED BY LOW TEMPERATURE CHEMICAL
VAPOR DEPOSITION (CVD) METHODS (<800°C), SINCE THE NANOTUBE LENGTH,
DIAMETER, ALIGNMENT, PURITY, DENSITY, AND ORIENTATION OF CNTS CAN BE
ACCURATELY CONTROLLED IN THE LOW TEMPERATURE CHEMICAL VAPOR
DEPOSITION (CVD) METHODS .
SYNTHESIS

7. PROPERTIES
1. THEIR MECHANICAL TENSILE STRENGTH CAN BE 400 TIMES THAT OF STEEL .
THEY ARE VERY LIGHT-WEIGHT – THEIR DENSITY IS ONE SIXTH OF THAT OF STEEL
BECAUSE CARBON NANOTUBES HAVE THE SP2 BONDS BETWEEN THE INDIVIDUAL
CARBON ATOMS AND THERE TENDENCY TO FORM ROPE TOGETHER VIA VANDER
WAAL FORCE MAKES IT STRONGER AND LIGHT IN WEIGHT .EVEN STRONGER THAN
SP3 BOND OF DAIMOND.
2. CNTs THERMAL CONDUCTIVITY IS BETTER THAN THAT OF A DIAMOND
SINCE CARBON NANOTUBES HAVE SUCH A PERFET STRUCTURE , THEY AVOID
DEGRADATION OF STRENGTH THAT YOU GET WITH OTHER MATERIAL
THE STIFFNESS OF CARBON BOND HELPS TRANSMIT THIS VIBRATION
THROUGHTOUT THE NANOTUBE PROVIDING GOOD THERMAL CONDUCTIVITY.
3. CARBON NANOTUBES HAVE A VERY HIGH ASPECT RATIO OF GREATER THAN 1000.
IN OTHER WORDS, IN RELATION TO THEIR LENGTH, THEY ARE EXTREMELY THIN

8. 4. LIKE GRAPHITE, THEY ARE HIGHLY CHEMICALLY STABLE AND RESIST VIRTUALLY
ANY CHEMICAL IMPACT UNLESS THEY ARE SIMULTANEOUSLY EXPOSED TO HIGH
TEMPERATURES AND OXYGEN - A PROPERTY THAT MAKES THEM EXTREMELY
RESISTANT TO CORROSION.
5. THEIR HOLLOW INTERIOR CAN BE FILLED WITH VARIOUS NANOMATERIALS,
SEPARATING AND SHIELDING THEM FROM THE SURROUNDING ENVIRONMENT
- A PROPERTY THAT IS EXTREMELY USEFUL FORNANOMEDICINE APPLICATIONS
LIKE DRUG DELIVERY.
6. THE WAY OUTER WALL OF CARBON NANOTUBES ARE WRAPPED , MAKES IT
CONDUCTIVE. THE WALL ATOMS ARE STRUCTURED IN A WAY THAT MAKES IT ROOM
TEMPERATURE ZERO GAP SEMI CONDUCTIVE BY MAKING ELECTRONS FREE TO
MOVE.

9. APPLICATIONS
CNTS HAVE BEEN MAKING QUITE AN IMPRESSION ON COMMERCIAL PRODUCTS FOR
SOME TIME NOW.
CARBON NANOTUBES ARE ALREADY BEING USED TO CONTROL OR ENHANCE
CONDUCTIVITY IN POLYMERS AND ARE ADDED TO ANTI-STATIC PACKAGING.
THE MOST POPULAR CURRENT USE FOR CNTS IS STRUCTURAL REINFORCEMENT. THEY
ARE ADDED TO OTHER MATERIALS LIKE REBAR TO CONCRETE BECAUSE OF THEIR
HIGH STRENGTH, LOW WEIGHT, AND FLEXIBILITY. CNT PRODUCTION IS ALSO USED IN
BULK COMPOSITE MATERIALS AND THIN FILMS.
THESE ARE THE FEW PLACE FOR APPLICATION OF CNTs:-
• CNTs field emission  CNTs thermal conductivity
• CNTs energy storage CNTs conductive properties
• Molecular electronics based on CNTs CNTs structural applications
• CNTs fibre and fabric CNTs biomedical applications
• CNTs Air & Water Filtration CNTs catalyst supports

10. CNTS THERMAL CONDUCTIVITY AND EXPANSION
CNTS HAVE OUTSTANDING HEAT CONDUCTIVITY, ELECTRICAL CONDUCTIVITY, AND
MECHANICAL PROPERTIES. THEY ARE PROBABLY THE BEST ELECTRON FIELD-EMITTER
POSSIBLE. CNTS ARE MOLECULARLY PERFECT, IN THE SENSE THAT THEY ARE
GENERALLY FREE OF PROPERTY-DEGRADING FLAWS IN THE NANOTUBE STRUCTURE.
THEIR MATERIAL PROPERTIES CAN THUS REACH CLOSE TO THE VERY HIGH LEVELS
INTRINSIC TO THEM. DUE TO THESE EXTRAORDINARY CHARACTERISTICS, CNTS CAN
BE PROSPECTIVELY USED IN A NUMBER OF APPLICATIONS.
CNTS BIOMEDICAL APPLICATIONS
SINCE A GREAT PART OF THE HUMAN BODY IS MADE UP OF CARBON, IT IS USUALLY
CONSIDERED A VERY BIOCOMPATIBLE MATERIAL. THE GROWTH OF CELLS ON CNTS
HAS BEEN DEMONSTRATED; THEREFORE, THEY APPARENTLY HAVE NO TOXIC EFFECT.
THE ABILITY TO FUNCTIONALIZE (CHEMICALLY MODIFY) THE SIDEWALLS OF CNTS
ALSO GIVES RISE TO BIOMEDICAL APPLICATIONS INCLUDING NEURON GROWTH AND
REGENERATION, AND VASCULAR STENTS. IT HAS ALSO BEEN DEMONSTRATED THAT A
SINGLE STRAND OF DNA CAN BE BONDED TO A NANOTUBE, WHICH CAN
SUBSEQUENTLY BE EFFECTIVELY INSERTED INTO A CELL.
CNTS AIR AND WATER FILTRATION
WITH THE ABILTY TO BLOCK TINIEST PARTICLE AND DESTROING SMALLEST BATERIAL
CNTS MAKES ITS USE IN PURIFICATION INDUSTRIES.

11. WASTE WATER TREATMENT
CNTs HAS LARGE SURFACE AREA THAT GIVES LARGE CAPACITY TO RETAIN WATER
SOLUBLE DRUG.
SOLAR CELL
DUE TO STRONG UV ABSORPTION CHARACTERSTICS , CNTs ARE POTENTIAL
CANDIDATES TO BE USED FOR
SOLAR CELL
RESEARCH HAS SHOWN THAT THEY PROVIDE SIZABLE INCREASE IN EFFICIENCY,
EVEN AT CURRENT UNOPTIMIZED STATE.
HYDROGEN STORAGE
BY TAKING ADVANTAGE OF CAPILLARY EFFECTS OF SMALL CARBON NANOTUBES,
IT IS POSSIBLE TO CONDENSE
GASES IN HIGH DENSITY INSIDE SINGLE WALL NANOTUBE.
THIS ALLOWS FOR GASES,MOST NOTABLE HYDROGEN TO BE STORED AT HIGH
DENSITIES WITHOUT BEING CONDENSED INTO LIQUID STATE. THESE METHOD
CAN BE USED IN VEHICLES IN PLACE OF FUEL TANKS.