nanotechnology and nano fibers

8/4/2019 Nanotechnology and Nano Fibers

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SKYLINE INSTITUTE OF ENGINEERING

& TECHNOLOGY GR.NOIDA

BYASHISH SHARMA

ME-3rd YEAR

NANO FIBER

l o a d i n g l o a d i n g l o a d i n g

0% 100%


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Nanotechnology and Nanofibers


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Nanotechnology

The study of control of matter on an atomic

and molecular scale.

Deals with structures the size of 3300 nanometers

or smaller (33 nm = 33/33,000,000,000 m or 330-9

m).

Involves engineering on a small scale to create

smaller, cheaper, lighter, and faster devices that

can do more things with less raw materials.


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Key Dimensions in Nanometers

An atom is about 0.3 nm in size.

Typical spacing between 2carbon atoms in a molecule is

0.332 0.335 nm.


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DNA double helix has a diameterof about 2 nm.

A bacterium of the genus Mycoplasma

has a length of 200 nm.


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A red blood cell is 6,000 nm in diameter.

A human hair is 80,000 nm in diameter.

To put this scale in context, the size of a nanometerto a meter, is the same as that of a marble to the sizeof the Earth.


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Properties of Nanoparticles

Materials reduced to the nanoscale can show

different properties compared to what they

exhibit on the macroscale.

Opaque substances may become transparent

(copper); stable materials turn combustible

(aluminum); insulators become conductors(silicon); and solids turn to liquids at room

temperature (gold).


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Nanoparticles tend to be more chemically

reactive than their ordinary sized counterparts

because they have more surface area.

An increase in surface area to volume ratio alters

the mechanical, thermal, and catalytic properties

of materials.


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Model of Surface-to-Volume

Comparisons

Neglecting spaces between the smaller boxes, the volumes of the

box on the left and the boxes on the right are the same but the

surface area of the smaller boxes added together is much greater

than the single box.

Single Box Ratio

6 m2

33

m3

= 6 m2/m3

Smaller Boxes Ratio

332 m2

33 m3= 332 m2/m3


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Another Way to Think of this Ratio

Using Sugar Cubes

Each individual cube is about 33

cm on a side, so each side has

an area of 33 cm

2

. With sixsides, it has a surface area of 6

cm2 and a volume of 33 cm3.

This is a surface area to volumeratio of 6 cm2/cm3


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A block made from 64sugar cubes is 4 cm ona side and has a surfacearea of 6 x 336 cm2 or96 cm2 and a volumeof 64 cm3.

This is a surface area tovolume ratio of 33.5 cm2/cm3.

If you compute the surface of all 64 individual cubes,you would have 64 x 6cm2 or 384 cm2 or 4 times moresurface area with the same total volume.


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An Example of the Affects of

Surface-to-Volume Ratios in Animals

Larger surface-to-volume ratio

Very susceptible to changes in heat

Smaller surface-to-volume ratio

Less susceptible to changes in heat


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Applications

From videotapes to DVDs and from cathode

ray tubes to flat screen TVs, nanotechnology

applications require team efforts from

biologists, chemists, physicists, engineers, andinformation technologists.

Example: a cochlear ear implant requiresphysiologists, electronic engineers, mechanical

engineers, and biomaterials experts


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Products Currently on the Market

Using Nanotechnology

Over 600 nanotech enabled

products are on the market

today. Some examples are:

Carbon nanotubes in bike

frames and tennis rackets

make the products stronger

and lighterThis bike frame weights 2.75 pounds


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Nano-size particles of titanium dioxide and zinc oxide

are less visible than the whitish particles of the oldersunscreens. They block UV light more effectively

without turning your skin white

Older sunscreen leaves a white sheen behind


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Self cleaning glass uses UV light to energize

nanoparticles to break down and loosen dirt onglass. Particles are also hydrophilic so water spreadsacross the glass evenly and helps wash the glassclean.

Coating fabric with nanoparticles helps repel thewater and other materials to make clothes stainresistant.

Nanoparticles of silver in antimicrobial bandagesblock the microbes cellular respiration, thus killingthem.


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Nanoparticles in scratch resistant coatings are

common on everything from cars to eyeglass lenses.

Bridgestone engineers developed a Quick Response

Liquid Powder Display, a flexible digital screen, using

nanotechnology.


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Nanofibers:What are they? Why are they important?


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What is a Nanofiber?

A nanofiber is a continuousfiber which has a diameter inthe range of billionths of ameter.

The smallest nanofibersmade today are between33.5 and 33.75 nanometers.

At the right a human hair(80,000 nanometers) isplace on a mat of nanofibers

Image from EPA.gov


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Nanofibers range in diameter of 2-600

nanometers and are very difficult to see with

the naked eye so they are studied usingmagnification

Spider dragline 3,000 nanometersElectron micrograph of nanofibers used for

tissue scaffolds


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Unique Properties of Nanofibers

Size: nanofibers are very small which gives them

unique physical and chemical properties and allows

them to be used in very small places.

Surface-to-volume ratio: nanofibers have a huge

surface area compared to their volume. So scientists

have lots of surface to work with!

The huge surface area available on a nanofiber makes it

very suitable for new technologies which require smaller

and smaller environments for chemical reactions to occur.

Increasing the surface area speeds up a chemical reaction.


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Making Nanofibers

Melt Fibers: some nanofibers can be made bymelting polymers and spinning or shooting them

through very small holes. As the fiber spins out it

stretches smaller and smaller...

Cotton candy is made by heating syrup to

a high temperature and then the liquid is

spun out through tiny holes. As the fiberspins it is pulled thinner and thinner. It

cools, hardens and, presto! Cotton

Candy!!


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Electrospinning to Make Nanofibers

An electric field pulls on

a droplet of polymer

solution at the tip of the

syringe and pulls out asmall liquid fiber. It is

pulled thinner and

thinner as it approaches

the collection plate.

Electrospinning Apparatus


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Electrospinning a Polymer Solution to

Produce Nanofibers

This picture shows the actual

spinning of a solution made of

the polymer PEO (polyethylene

oxide) dissolved in water.

Polymer solutions can be

electrospun because of their long

repeating units.

The resulting fiber is collected

below on a grounded plate

Image courtesy of Reneker Group

The University of Akron, College of Polymer Science


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Here you can see the individual fiber being pulled downward

toward the grounded collection plate.




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PEO (Polyethylene Oxide) Nanofibers


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Uses of Nanofibers

High surface area: Filtration, Protective clothing.

Filter applications: Oil droplet

coalescing on nanofibers increase

the capture rate of the oil fog.

Nano-Tex fabrics with water, cranberry

juice, vegetable oil, and mustard after30 minutes (left) and wiped off with

wet paper towel (right)


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Uses of Nanofibers continued.

Support: Template for

making different

structures/coatings,

catalysts/enzyme

supports.

Tissue Scaffolding:Fibroblast cells grown

on PLGA nanofibers. Image by Amy Liu, Hoover High School Student


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Strength: Reinforced

composites by

nanofibers, twisted in

yarns.

New yarns with

outstanding wickingproperties: Here

electrospun nylon fibers

are spun into yarns.



and Samantha Loutzenheiser, Hoover High School.


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Encapsulation: Drug delivery,

Scaffolds for growing cells,

Agriculture.

Water filtration: EDTA, achelating compound, has been

encapsulated in tecophilic

nanofibers.

These fibers in a water filter can

remove heavy metals,

particularly lead, cadmium and

copper.

Image by Joe Sinha, Hoover High School Student


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Light Weight: Produce Solar

sails in space, Aircraft wings,

Bullet-proof vests.

New breathable bullet-proof

vest: NomexNanofibers




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Structure: Fuel cell, Micro/Nano

electronic devices

Nanofibers can be used togreatly decrease the size of

a fuel cell while increasing

the electrical output.


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Website Resources

http://www.nanitenews.com/

http://electrospun.blogspot.com/

http://micro.magnet.fsu.edu/primer/java/

scienceopticsu/powersof330/

http://www.nnin.org/edunews_6.html
http://www.nanitenews.com/http://electrospun.blogspot.com/http://micro.magnet.fsu.edu/primer/java/%0Bscienceopticsu/powersof10/http://micro.magnet.fsu.edu/primer/java/%0Bscienceopticsu/powersof10/http://www.nnin.org/edunews_6.htmlhttp://www.nnin.org/edunews_6.htmlhttp://micro.magnet.fsu.edu/primer/java/%0Bscienceopticsu/powersof10/http://micro.magnet.fsu.edu/primer/java/%0Bscienceopticsu/powersof10/http://micro.magnet.fsu.edu/primer/java/%0Bscienceopticsu/powersof10/http://electrospun.blogspot.com/http://www.nanitenews.com/

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