Electrospinning of nanofibers 2
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Electrospinning of nanofibers 2 Electrospinning of nanofibers 2 Presentation Transcript

  • 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.Polycaprolactonenanofiber (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 nano10,000X 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) nanofibers
    With 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) nanofibers
    with 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) nanofiber
    mesh.
    (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)‏
  • 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
    Electrical conductors
    - Ultra small devices
    Filter media
    - Higher filter efficiency
    Optical applications
    • Liquid crystal optical shutters
    Protective clothing
    • Breathable fabric that blocks chemicals
    Material reinforcement
    - Higher fracture toughness
    - Higher delamination resistance
    Ramakrishna et al. 2004
  • 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]
  • ELECTROSPINNING
    Figure 12. Schematic of Electrospinning Process
    Courtesy: www.che.vt.edu
  • ELECTROSPINNING
    Figure 13 The distribution of charge in the fiber
    changes 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:
    that the surface of the cone is an equipotential surface and
    (2) that the cone exists in a steady state equilibrium
  • Taylor Cone
    Potential
    Equipotential surface
    The zero of the Legendre polynomial between 0 and pi
    is 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
  • 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
  • Taylor Cone.
    J.T.Garcia, E.A. Florido
  • Electrospinning
    v=0.1m/s
    moving charges e
    bending force on charge e
    E ~ 105V/m
    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-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
  • Electro-spinning
    bending instability of electro-spun jet
    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
  • 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)
  • 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
    PEO microfibers, JennetteRabo, 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.
  • 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 ElectrospunPolycaprolactone. 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 ElectrospunPolyaniline-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 PolycaprolactoneNanofibers through Electrospinning, Proceedings of the SamahangPisikangPilipinas, 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 SamahangPisikangPilipinas, ISSN 1656-2666, vol. 5,October 22-24, 2008.
    B.J.Garcia. Morphological and Molecular Characterization of Electrospun Polyvinyl chloride-PolyanilineNanofibers. 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