Electrospinning of nanofibers 2
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Transcript of Electrospinning of nanofibers 2
ELECTROSPINNING OF NANOFIBERS
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).
NANOFIBERS
Figure 1. Comparison between human hair and nanofiber web [1].
NANOFIBERS
Figure 2. Entrapped pollen spore on nanofiber web [1].
NANOFIBERS
Figure 3. Comparison of red blood cell with nanofibers web [1].
NANOFIBERS
Figure 4. Ultra – Web® Nanofiber Filter Media used commercially. (taken from Grafe, 2003)
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)
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)
First nanofibers produced in the Material Science Lab, IMSP, UPLB
Figure 7. SEM Micrograph of Poly(DL-lactide-co-glycolide) nanofibersWith diameter range of 59nm-126 nm.(J.Clarito, E.A.Florido, October 2008)
First nanofibers produced in the Material Science Lab, IMSP, UPLB
Figure 8. SEM Micrograph of Poly(DL-lactide-co-glycolide) nanofiberswith diameters of 86 nm, 194 nm, 201 nm.(J.Clarito, E.A.Florido, October 2008)
First nanofibers produced in the Material Science Lab, IMSP, UPLB
Figure 9. SEM Micrograph of Poly(DL-lactide-co-glycolide) nanofibermesh.(J.Clarito, E.A.Florido, October 2008)
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)
First nanofibers produced in the Material Science Lab, IMSP, UPLB
Figure 11. 22 nm-diameter polyvinyl chloride nanofiber with a porous microfiber in the background. (J.Garcia, E.A.Florido, February 2009)
Applications of Nanofibers
Material Reinforcements and filters (BHOWMICK, S. A. Et al. 2006)
Tissue and Organ Implants (RAMAKRISHNA, S.M., et al. 2004)
Extra Cellular Matrix (QUEEN, 2006)
Cosmetics- Higher utilization- Higher transfer rate
Drug delivery- Increased dissolution rate- Drug-nanofiber interlace
Electrical conductors- Ultra small devices
Filter media- Higher filter efficiency
Haemostatic devices- Higher efficiency in fluid
absorption
Wound dressing- Prevents scar- Bacterial shielding
Protective clothing- Breathable fabric that
blocks chemicals
Optical applications- Liquid crystal optical shutters
Sensor devices- Higher sensitivity- For cells, arteries and veins
Material reinforcement- Higher fracture toughness- Higher delamination resistance
Tissue engineering scaffolds- Adjustable biodegradation rate- Better cell attachment- Controllable cell directional growth
Medical prostheses- Lower stress concentration- Higher fracture strength
Polymer Nanofiber
Ramakrishna et al. 2004
ELECTROSPINNINGUses 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]
ELECTROSPINNING
Figure 12. Schematic of Electrospinning Process Courtesy: www.che.vt.edu
ELECTROSPINNING
Figure 13 The distribution of charge in the fiberchanges as the fiber dries out during flight
Figure 14. Electrospinning set-up in the IMSP Physics Division Materials Science Laboratory. J.I.Zerrudo, E.A. Florido
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
Taylor Cone
• Taylor angle. This angle is more precisely where is the first zero of (the Legendre polynomial of order 1/2).
two assumptions: (1) that the surface of the cone is an
equipotential surface and (2) that the cone exists in a steady state
equilibrium
Taylor ConePotential
Equipotential surface
The zero of the Legendre polynomial between 0 and piis 130.70990 which is the complement (supplement)of the Taylor angle.
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
NANOFIBRES T. A. Kowalewski, A. L. Yarin & S.
Błoński, EFMC 2003, Toulouse
Classical liquid jet
Orifice – 0.1mm
Primary jet diameter ~ 0.2mm
0.1mm
Micro-jet diameter ~ 0.005mm
Gravitational, mechanical or electrostatic pulling limited to l/d ~ 1000 by capillary instabilityTo reach nano-range:
jet thinning ~10-3 draw ratio ~106 !
Taylor Cone.
J.T.Garcia, E.A. Florido
NANOFIBRES T. A. Kowalewski, A. L. Yarin & S. Błoński, EFMC 2003,
Toulouse
Electrospinning
E ~ 105V/m
v=0.1m/s
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
Electro-spinningSimple model for elongating viscoelastic thread
Non-dimensional length of the thread as a function of electrostatic potential
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
NANOFIBRES T. A. Kowalewski, A. L. Yarin & S. Błoński, EFMC 2003, Toulouse
Electro-spinning
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
bending instability of electro-spun jet
charges moving along spiralling path
Parameters
1. Molecular Weight, Molecular-Weight Distribution and Architecture (branched, linear etc.) of the polymer
2. Solution properties (viscosity, conductivity & and surface tension)
3. Electric potential, Flow rate & Concentration4. Distance between the capillary and collection screen5. Ambient parameters (temperature, humidity and air
velocity in the chamber)6. Motion of target screen (collector)
Figure 14. Electrospinning set-up in the IMSP Physics Division Materials Science Laboratory. J.I.Zerrudo, E.A. Florido
Fibers produced during electrospinning.
J.I.Zerrudo, E.A. Florido
Fibers produced during electrospinning.
J.I.Zerrudo, E.A. Florido
PVC Fibers produced during electrospinning.
J.T.Garcia, E.A. Florido
PVC Fibers produced during electrospinning.
J.T.Garcia, E.A. Florido
A.O.Advincula, E.A. Florido
J.C. La Rosa, E.A. Florido
Electrospinning in MatPhy Lab, IMSP, UPLB
1. PEO microfibers, Jennette Rabo, Maricon R. Amada, 2006
2. Polyaniline and Polyaniline/Polyester microfibers, Jefferson D. Diego, M.R.Amda, Emmanuel A. Florido, 2006
3. Polycaprolactone/Polyethylene Oxide nanofibers, Juzzel Ian Zerrudo, Emmanuel A. Florid0, 2008
4. Polycaprolactone (pcl)/Polyethylene oxide (peo)/iota carrageenan (ιcar) blends, Serafin M. Lago III, Teoderick Barry R. Manguerra, 2008.
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, 2008
5. Polyvinyl Chloride (PVC) nanofibers from scrap PVC pipes, Ben Jairus T. Garcia, 2009
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 2010. 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 2010. Undergraduate Thesis, Adviser: EAFlorido
• H.P.Halili. Effect of Solution Viscosity and Needle Diameter on Fiber Diameter of Electrospun Polycaprolactone. IMSP, UPLB. October 2010. Undergraduate Thesis, Adviser: EAFlorido. Co-Adviser: J.I.B. Zerrudo
• 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 2009. 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 2009. 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 1656-2666, vol. 5,October 22-24, 2008.
• 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 1656-2666, vol. 5,October 22-24, 2008.
• B.J.Garcia. Morphological and Molecular Characterization of Electrospun Polyvinyl chloride-Polyaniline Nanofibers. IMSP, UPLB. April 2009. Undergraduate Thesis, Adviser: EAFlorido
• J.D. Diego. Electrospinning of Polyaniline and Polyaniline/Polyester Based Fibers. IMSP, UPLB. November 2006.Undergraduate Thesis, Adviser: EAFlorido