1. ELECTROSPINNING OF NANOFIBERS

2. NANOFIBERS
With dimension of 100 nanometers (nm) or less (National Science Foundation, India)
As defined by the Non – woven industry, nanofiber is any fiber that has a diameter of less than 1 micron (<1000 nm) (Hegde, R.R. et al, 2005).

3. Figure 1. Comparison between human hair and nanofiber web [1].
NANOFIBERS
Figure 1. Comparison between human hair and nanofiber web [1].

4. NANOFIBERS
Figure 2.  Entrapped pollen spore on nanofiber web [1].

5. NANOFIBERS
Figure 3. Comparison of red blood cell with nanofibers web [1].

6. NANOFIBERS
Figure 4. Ultra – Web® Nanofiber Filter Media used commercially.
(taken from Grafe, 2003)

7. First nanofibers produced in the Material Science Lab, IMSP, UPLB
Figure 5. Polycaprolactone nanofiber (a) and (b) has fiber diameters
between 273 nm to 547 nm. SEM taken with 10,000X magnification.
(J.I.Zerrudo, E.A.Florido, 2008)

8. First nanofibers produced in the Material Science Lab, IMSP, UPLB
Figure 6. 75:25 Polycaprolactone(PCL)/Polyethylene Oxide (PEO)
blend nano 10,000X magnification.
(J.I.Zerrudo, E.A.Florido, SPP Physics Congress, October 2008)

9. First nanofibers produced in the Material Science Lab, IMSP, UPLB
Figure 7. SEM Micrograph of Poly(DL-lactide-co-glycolide) nanofibers
With diameter range of 59nm-126 nm.
(J.Clarito, E.A.Florido, October 2008)

10. First nanofibers produced in the Material Science Lab, IMSP, UPLB
Figure 8. SEM Micrograph of Poly(DL-lactide-co-glycolide) nanofibers
with diameters of 86 nm, 194 nm, 201 nm.
(J.Clarito, E.A.Florido, October 2008)

11. First nanofibers produced in the Material Science Lab, IMSP, UPLB
Figure 9. SEM Micrograph of Poly(DL-lactide-co-glycolide) nanofiber
mesh.
(J.Clarito, E.A.Florido, October 2008)

12. First nanofibers produced in the Material Science Lab, IMSP, UPLB
Figure 10. SEM Micrograph of Polyvinyl chloride nanofiber with
at least 76 nm diameter.
(J.Garcia, E.A.Florido, February 2009)

13. First nanofibers produced in the Material Science Lab, IMSP, UPLB
Figure nm-diameter polyvinyl chloride nanofiber with
a porous microfiber in the background.
(J.Garcia, E.A.Florido, February 2009)

14. Applications of Nanofibers
Material Reinforcements and filters (BHOWMICK, S. A. Et al. 2006)‏
Tissue and Organ Implants (RAMAKRISHNA, S.M., et al )‏
Extra Cellular Matrix (QUEEN, 2006)‏

15. Ramakrishna et al. 2004 Polymer Nanofiber Tissue engineering scaffolds
- Adjustable biodegradation rate
- Better cell attachment
- Controllable cell directional growth
Wound dressing
- Prevents scar
- Bacterial shielding
Medical prostheses
- Lower stress concentration
- Higher fracture strength
Haemostatic devices
- Higher efficiency in fluid absorption
Drug delivery
- Increased dissolution rate
- Drug-nanofiber interlace
Polymer Nanofiber
Sensor devices
- Higher sensitivity
- For cells, arteries and veins
Cosmetics
- Higher utilization
- Higher transfer rate
Filter media
- Higher filter efficiency
Electrical conductors
- Ultra small devices
Protective clothing
Breathable fabric that blocks chemicals
Material reinforcement
- Higher fracture toughness
- Higher delamination resistance
Optical applications
Liquid crystal optical shutters
Ramakrishna et al. 2004

16. ELECTROSPINNING
Uses high voltage to draw very fine fibers (micro- or nano-scale) from a liquid (soloution or melt).
The high voltage produces an electrically charged jet of polymer solution or melt, which dries or solidifies leaving a polymer fiber
the process was patented in 1934 by Formhals [2-4]

17. ELECTROSPINNING Figure 12. Schematic of Electrospinning Process
Courtesy:

18. ELECTROSPINNING Figure 13 The distribution of charge in the fiber
changes as the fiber dries out during flight

19. Figure 14. Electrospinning set-up in the IMSP Physics
Division Materials Science Laboratory.
J.I.Zerrudo, E.A. Florido

22. Taylor Cone
refers to the cone observed in electrospinning, electrospraying and hydrodynamic spray processes from which a jet of charged particles emanates above a threshold voltage
was described by Sir Geoffrey Ingram Taylor in 1964 before electrospray was "discovered“
to form a perfect cone required a semi-vertical angle of 49.3° (a whole angle of 98.6°) , the shape of such a cone approached the theoretical shape just before jet formation – Taylor Angle

23. Taylor Cone
Taylor angle. This angle is more precisely where is the first zero of (the Legendre polynomial of order 1/2).
two assumptions:
that the surface of the cone is an equipotential surface and
(2) that the cone exists in a steady state equilibrium

24. Taylor Cone Potential Equipotential surface
The zero of the Legendre polynomial between 0 and pi
is which is the complement (supplement)
of the Taylor angle.

25. Taylor Cone
When a sufficiently high voltage is applied to a liquid droplet, the body of the liquid becomes charged, and electrostatic repulsion counteracts the surface tension and droplet is stretched, at a critical point a stream of liquid erupts from the surface. This point of eruption is known as the Taylor cone

26. Classical liquid jet  0.1mm  Orifice – 0.1mm
Primary jet diameter ~ 0.2mm
Micro-jet diameter ~ 0.005mm
Gravitational, mechanical or
electrostatic pulling limited to
l/d ~ 1000 by capillary
instability
To reach nano-range:
jet thinning ~10-3
draw ratio ~106 !
NANOFIBRES T. A. Kowalewski, A. L. Yarin & S. Błoński, EFMC 2003, Toulouse

27. Taylor Cone.
J.T.Garcia, E.A. Florido

29. Electrospinning v=0.1m/s E ~ 105V/m
moving charges e
bending force on charge e
viscoelastic and surface tension resistance
Moving charges (ions) interacting with electrostatic field amplify bending instability, surface tension and viscoelasticity counteract these forces
NANOFIBRES T. A. Kowalewski, A. L. Yarin & S. Błoński, EFMC 2003, Toulouse

30. Simple model for elongating viscoelastic thread
Electro-spinning
Simple model for elongating viscoelastic thread
Stress balance:  - viscosity, G – elastic modulus stress,
 stress tensor, dl/dt – thread elongation
Momentum balance: Vo – voltage, e – charge, a – thread radius, h- distance pipette-collector
Kinematic condition for thread velocity v
Non-dimensional length of the thread as a function of electrostatic potential
NANOFIBRES T. A. Kowalewski, A. L. Yarin & S. Błoński, EFMC 2003, Toulouse

31. Electro-spinning bending instability of electro-spun jet E ~ 105V/m
charges moving along spiralling path
E ~ 105V/m
Bending instability enormously increases path of the jet, allowing to solve problem: how to decrease jet diameter 1000 times or more without increasing distance to tenths of kilometres
NANOFIBRES T. A. Kowalewski, A. L. Yarin & S. Błoński, EFMC 2003, Toulouse

32. Parameters
Molecular Weight, Molecular-Weight Distribution and Architecture (branched, linear etc.) of the polymer
Solution properties (viscosity, conductivity & and surface tension)
Electric potential, Flow rate & Concentration
Distance between the capillary and collection screen
Ambient parameters (temperature, humidity and air velocity in the chamber)
Motion of target screen (collector)

33. Figure 14. Electrospinning set-up in the IMSP Physics
Division Materials Science Laboratory.
J.I.Zerrudo, E.A. Florido

34. Fibers produced during electrospinning.
J.I.Zerrudo, E.A. Florido

35. Fibers produced during electrospinning.
J.I.Zerrudo, E.A. Florido

36. PVC Fibers produced during electrospinning.
J.T.Garcia, E.A. Florido

38. PVC Fibers produced during electrospinning.
J.T.Garcia, E.A. Florido

40. A.O.Advincula, E.A. Florido

42. J.C. La Rosa, E.A. Florido

43. Electrospinning in MatPhy Lab, IMSP, UPLB
PEO microfibers, Jennette Rabo, Maricon R. Amada, 2006
Polyaniline and Polyaniline/Polyester microfibers, Jefferson D. Diego, M.R.Amda, Emmanuel A. Florido, 2006
Polycaprolactone/Polyethylene Oxide nanofibers, Juzzel Ian Zerrudo, Emmanuel A. Florid0, 2008
Polycaprolactone (pcl)/Polyethylene oxide (peo)/iota carrageenan (ιcar) blends, Serafin M. Lago III, Teoderick Barry R. Manguerra, 2008.

44. Electrospinning in MatPhy Lab, IMSP, UPLB
4. Poly (DL-lactide-co-glycolide)(85:15) PLGA and PLGA/Polycaprolactone (PCL) nanofibers, Christian Joseph Clarito, Emmanuel A. Florido, Polyvinyl Chloride (PVC) nanofibers from scrap PVC pipes, Ben Jairus T. Garcia, 2009

45. Nanoresearch in UPLB: Physics Division, Institute of Mathematical Sciences and Physics, CAS
K.S.A. Revelar. An Investigation on the Morphological and Antimicrobial Properties of Electrospun Silver Nanoparticle-Functionalized Polyvinyl Chloride Nanofiber Membranes. IMSP, UPLB. April Undergraduate Thesis, Adviser: EAFlorido. Co-Adviser: R.B.Opulencia
A.O.Advincula. Effect of varying Areas of Parallel Plates on Fiber Diameter of Electrospun Polyvinyl Chloride. IMSP, UPLB. April Undergraduate Thesis, Adviser: EAFlorido
H.P.Halili. Effect of Solution Viscosity and Needle Diameter on Fiber Diameter of Electrospun Polycaprolactone. IMSP, UPLB. October Undergraduate Thesis, Adviser: EAFlorido. Co-Adviser: J.I.B. Zerrudo

46. J.C.M. La Rosa. Effects of Variation of Distance Between Needle Tip and Collector On the Fabrication of Polyaniline (PANI)-Polyvinyl Chloride (PVC) Blend Nanofibers. IMSP, UPLB. April Undergraduate Thesis, Co-Adviser: EAFlorido
M.J.P.Gamboa. The Effects of Viscosity on the Morphological Characteristics of Electrospun Polyaniline-Polyvinyl Acetate (PAni-PVAc) Nanofibers. IMSP, UPLB. April Undergraduate Thesis, Co-Adviser: EAFlorido
J.I.B. Zerrudo, E.A. Florido, M.R. Amada, Fabrication of Polycaprolactone Nanofibers through Electrospinning, Proceedings of the Samahang Pisika ng Pilipinas, ISSN , vol. 5,October 22-24, 2008.

47. J. I. B. Zerrudo, E. A. Florido, M. R. Amada, B. A
J.I.B. Zerrudo, E.A. Florido, M.R. Amada, B.A.Basilia, Fabrication of Polycaprolactone/Polyehtylene Oxide Nanofibers through Electrospinning, Proceedings of the Samahang Pisika ng Pilipinas, ISSN , vol. 5,October 22-24, 2008.
B.J.Garcia. Morphological and Molecular Characterization of Electrospun Polyvinyl chloride-Polyaniline Nanofibers. IMSP, UPLB. April Undergraduate Thesis, Adviser: EAFlorido
J.D. Diego. Electrospinning of Polyaniline and Polyaniline/Polyester Based Fibers. IMSP, UPLB. November 2006.Undergraduate Thesis, Adviser: EAFlorido