3. • Nanofibers are defined as fibers with diameters
less than 100 nanometres.
• In the textile industry, this definition is often
extended to include fibers as large as 1000 nm
diameter.
• At the right a human hair (80,000 nanometres)
is place on a mat of Nanofibers.
• Nanofibers range in diameter of 2-600
nanometres and are very difficult to see with the
naked eye so they are studied using magnification
• Much research has been done on spider dragline
silks. The strength of a spider dragline is much
stronger than a steel fiber of equivalent size.
Introduction
4. 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.
Unique Properties of Nanofibers
5. • They can be produced by…
Melt processing
Interfacial polymerization
Electro spinning
Apart from this the nanofibers can also be produced by
Anti-solvent induced polymer precipitation and electrostatic spinning.
Carbon nanofibers are produced by catalytic synthesis.
Production of Nanofibers
6. • “Melt” Fibers: some nanofibers can be made by
melting polymers and spinning or shooting them
through very small holes. As the fiber spins out it
stretches smaller and smaller...
• The smallest nanofibers are made by
electrospinning solutions of polymers.
• These solutions are place in a pipette or syringe
with a small wire inserted.
• The wire will serve as an electrode which is hooked
to a high voltage power supply. A collection plate
where fibers will land and deposit is attached to the
ground of the power supply.
• Cotton candy is made by heating syrup to a high
temperature and then the liquid is spun out through
tiny holes. As the fiber spins it is pulled thinner and
thinner. It cools, hardens and, presto! Cotton
Candy!!
Melt Processing
7. • Generally, polymeric nanofibers are produced by an electro-spinning
process.
• Electro-spinning is a process that spins fibers of diameters ranging from
10nm to several 100nm.
• This method has been known since 1934 when the first patent on electro-
spinning was filed.
• Fiber properties depend on field uniformity, polymer viscosity, electric
field strength and DCD (distance between nozzle and collector).
• Advancements in microscopy such as scanning electron microscopy has
enabled us to better understand the structure and morphology of
nanofibers.
Electro-spinning Process
8. • An electric field pulls on a
droplet of polymer
• solution at the tip of the syringe
and pulls out a small liquid fiber.
• It is pulled thinner and thinner
as it approaches the collection
plate.
Electro-spinning Process
9. • 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
Electro-spinning Process
11. Drug delivery system:
• Encapsulation of the drug inside the electrospun fiber
• Improve therapeutic efficacy due to the high surface area and safety of
drugs (Dissolution rate of a particulate drug increases with increasing
surface area of both the drug and the corresponding carrier if needed.)
Wound dressing:
• Novel polymeric composite materials that have antimicrobial properties
and variable surface properties that can reduce attachment and adhesion
to the wound.
• Wound dressings having antibacterial properties
• would be highly desirable for wounded personnel
Application of Nanofibers
13. • High surface area: Filtration, Protective clothing.
• Filter applications: Oil droplet coalescing on
Nanofibers increase .
• Nano-Tex fabrics with water, cranberry juice,
vegetable oil, and mustard after 30 minutes (left)
and wiped off with wet paper towel (right).
Application of Nanofibers
14. Structure: Fuel cell, Micro/Nano electronic devices
• Nanofibers can be used to greatly decrease the size of a
fuel cell while increasing the electrical output.
Application of Nanofibers
15. ORTHOPEDIC AND NEURAL IMPLANTS
• Nano fibers are compatible with human
tissues.
• Can create better bone & neural implants.
• Compatibility arises from similarity in body
tissue and Nano structure.
• Orthopedic Nano implants – Commercially
available in 5 – 10 years.
• Recently, researchers have found that
nanofiber meshes could be used to fight
against the HIV-1 virus, and be able to be
used as a contraception.
Application of Nanofibers
