Carbon Nano Tube (CNT)

NanochemistryCarbon Nanotubes(CNTs)ByAbdul WahabM.Sc Chemistry1

1

Table Of Content2

Nanochemistry NanochemistryorNanotechnologyare related with the production and the reactions ofnanoparticlesand theircompounds. Thisstudythesynthesisandanalysisofmaterialsinthenanoscalerange(1-100 nanometers). This science use methodologies from thesynthetic chemistryand the material's chemistry.3

For ExampleAnd in energy, optical engineering, defense and security, nanobio technology, nano devices, nano fabrics, bio engineering and many others.4

Nanoparticlesare particles between 1 and 100 nanometers in size.One nanometer corresponds to five atoms side by side.OR An apple compared to earth.OREarth compared to this galaxy(milky way).ORGalaxy compared to this universe.

5

History of CNTsIn 1970 Morinobu Endo first grew carbon fibers about 7 nm in diameter during PhD studies at the University of Orleans in France. Filaments were not recognized as nanotubes and were not studied. ButIn 1991 Sumio Iijima at NEC Laboratory in Tsukuba observed carbon nanotubes for first time. And from here it came to know.

6

Carbon Nanotubes (CNTs) Carbon nanotubes(CNTs) are allotropes of carbonwith acylindrical nanostructure. These cylindricalcarbonmoleculeshave unusual properties, which are valuable for nanotechnology,electronics,opticsand other fields ofmaterials scienceand technology.

7

Types of Carbon nanotubesClassified mainly into two types:Single Walled NanoTubes(SWNT) Single-wall nanotubes (SWNT) are tubes of graphite, which is rolled into a cylinder.

8

2. Multi Walled NanoTubes(MWNT) Multi-wall nanotubes can appear either in the form of a coaxial assembly of SWNTsimilar to a coaxial cable, or as a single sheet of graphite rolled into the shape of a scroll.Structure of MWNT is less well understood because of its greater complexity and variety.

9

How nanotubes are made? They can be made by following method like:Arc dischargeLaser AblationChemical Vapor DecompositionNatural, incidental and controlled flame environments

10

Arc DischargeAnelectric arc, orarc discharge, is anelectrical breakdownof a gas that makes insulator medium conductive.Nanotubes were observed in 1991 firstly by this method.The yield both single- and multi-walled nanotubes.

11

Chemical vapor depositionChemical vapor deposition (CVD) is the most popular method of producing CNTs nowadays. Chemical vapor deposition (CVD) is a versatile process in which gas-phase molecules are decomposed to reactive species, leading to film or particle growth.

12

Laser Ablation Laser ablationis the process of removing material from a solid surface by irradiating it with alaserbeam. The laser ablation method primarily single-walled carbon nanotubes with a controllable diameter determined by the reactiontemperature. However, it is more expensive than either arc discharge or chemical vapor deposition.

13

Natural, incidental, and controlled flame environmentsCarbon nanotubes are not necessarily products of high-tech laboratories; they are commonly formed in environment.However, these naturally occurring varieties can be highly irregular in size and quality because the environment in which they are produced is often highly uncontrolled. Thus, they can lack in the high degree of uniformity necessary to satisfy the many needs of both research and industry.14

Properties of CNTsProperties15

Strength PropertiesCarbon nanotubes have the strongest tensile strength and highest modulus of elasticity than any material known.A nanotube with cross section 1 square millimeter can lift up more than 6000kg weight.

MaterialStrength(TPa)CNTs1Kevlar0.13Stainless Steel0.2Glass0.07/0.08

16

Electrical PropertiesCarbon nanotubes can be conductor, insulator and semiconductor depending on the type of CNT.Metallic nanotubes can carry an electrical current density of 4109 A/cm2 which is more than 1,000 times greater than metals such as copper.

17

Thermal PropertiesCarbon nanotubes can transmit up to 6000 watts per meter per Kelvin at room temperature; compare this to copper, a metal well-known for its good thermal conductivity, which transmits 385 watts per meter per K. The temperature stability of carbon nanotubes is estimated to be up to 2800oC.18

One dimensional transportElectron transport in carbon nanotubes will only propagate along the axis of the tube. Because of this special transport property, carbon nanotubes are frequently referred to as one-dimensional.19

DefectsDefects can occur in the form of atomic vacancies. High levels of such defects can lower the tensile strength by up to 85%.Because of the very small structure of CNTs, the tensile strength of the tube is dependent on its weakest segment in a similar manner to a chain, where the strength of the weakest link becomes the maximum strength of the chain.

20

ApplicationsNanotubes hold the promise of creating novel devices, such as carbon-based single-electron transistors, that significantly smaller than conventional transistors. These maybe used for the fabrication of the next generation of energy storage, super capacitors, field emission transistors, solar cell, and biomedical devices and implants.

21

In medicine: applications are in bone tissue engineering, fluorescent and photoacoustic imaging and biosensors etc.In Composite materials:mixtures, yarns, alloys, coating and films etc.In MicroelectronicsTransistor, solar cells and thermal management etc. In ChemicalDesalination, filters and nanowires etc.And many other mechanical and optical applications

22

ToxicityAvailable data clearly show that, under some conditions, nanotubes can cross membrane barriers and can induce harmful effects such as inflammatory and fibrotic reactions.

Cardiac amyloidosis

Inflammation23

Hazard to health

24

Hazard to environment

25

Future Of CNTsThese tiny tubes have big future. Research on their chemistry is continued.

26

Summary27

28