Electrospinning of nanofibers 2

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Electrospinning of nanofibers 2

  1. 1. ELECTROSPINNING OF NANOFIBERS<br />
  2. 2. NANOFIBERS<br /><ul><li>With dimension of 100 nanometers (nm) or less (National Science Foundation, India)
  3. 3. 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).</li></li></ul><li>NANOFIBERS<br />Figure 1. Comparison between human hair and nanofiber web [1]. <br />
  4. 4. NANOFIBERS<br />Figure 2.  Entrapped pollen spore on nanofiber web [1].<br />
  5. 5. NANOFIBERS<br />Figure 3. Comparison of red blood cell with nanofibers web [1].<br />
  6. 6. NANOFIBERS<br />Figure 4. Ultra – Web® Nanofiber Filter Media used commercially.<br />(taken from Grafe, 2003)<br />
  7. 7. First nanofibers produced in the Material Science Lab, IMSP, UPLB<br />Figure 5.Polycaprolactonenanofiber (a) and (b) has fiber diameters<br />between 273 nm to 547 nm. SEM taken with 10,000X magnification.<br />(J.I.Zerrudo, E.A.Florido, 2008)<br />
  8. 8. First nanofibers produced in the Material Science Lab, IMSP, UPLB<br />Figure 6. 75:25 Polycaprolactone(PCL)/Polyethylene Oxide (PEO) <br />blend nano10,000X magnification.<br />(J.I.Zerrudo, E.A.Florido, SPP Physics Congress, October 2008)<br />
  9. 9. First nanofibers produced in the Material Science Lab, IMSP, UPLB<br />Figure 7. SEM Micrograph of Poly(DL-lactide-co-glycolide) nanofibers<br />With diameter range of 59nm-126 nm.<br />(J.Clarito, E.A.Florido, October 2008)<br />
  10. 10. First nanofibers produced in the Material Science Lab, IMSP, UPLB<br />Figure 8. SEM Micrograph of Poly(DL-lactide-co-glycolide) nanofibers<br />with diameters of 86 nm, 194 nm, 201 nm.<br />(J.Clarito, E.A.Florido, October 2008)<br />
  11. 11. First nanofibers produced in the Material Science Lab, IMSP, UPLB<br />Figure 9. SEM Micrograph of Poly(DL-lactide-co-glycolide) nanofiber<br />mesh.<br />(J.Clarito, E.A.Florido, October 2008)<br />
  12. 12. First nanofibers produced in the Material Science Lab, IMSP, UPLB<br />Figure 10. SEM Micrograph of Polyvinyl chloride nanofiber with <br />at least 76 nm diameter. <br />(J.Garcia, E.A.Florido, February 2009)<br />
  13. 13. First nanofibers produced in the Material Science Lab, IMSP, UPLB<br />Figure 11. 22 nm-diameter polyvinyl chloride nanofiber with <br />a porous microfiber in the background. <br />(J.Garcia, E.A.Florido, February 2009)<br />
  14. 14. Applications of Nanofibers<br /><ul><li>Material Reinforcements and filters (BHOWMICK, S. A. Et al. 2006)‏
  15. 15. Tissue and Organ Implants (RAMAKRISHNA, S.M., et al. 2004)‏
  16. 16. Extra Cellular Matrix (QUEEN, 2006)‏</li></li></ul><li>Tissue engineering scaffolds<br />- Adjustable biodegradation rate<br />- Better cell attachment<br />- Controllable cell directional growth<br />Wound dressing<br />- Prevents scar<br />- Bacterial shielding<br />Medical prostheses<br />- Lower stress concentration<br />- Higher fracture strength<br />Haemostatic devices<br />- Higher efficiency in fluid absorption<br />Drug delivery<br />- Increased dissolution rate<br />- Drug-nanofiber interlace<br />Polymer Nanofiber<br />Sensor devices<br />- Higher sensitivity<br />- For cells, arteries and veins<br />Cosmetics<br />- Higher utilization<br />- Higher transfer rate<br />Electrical conductors<br />- Ultra small devices<br />Filter media<br />- Higher filter efficiency<br />Optical applications<br /><ul><li>Liquid crystal optical shutters</li></ul>Protective clothing<br /><ul><li>Breathable fabric that blocks chemicals</li></ul>Material reinforcement<br />- Higher fracture toughness<br />- Higher delamination resistance<br />Ramakrishna et al. 2004<br />
  17. 17. ELECTROSPINNING<br /><ul><li>Uses high voltage to draw very fine fibers (micro- or nano-scale) from a liquid (soloution or melt).
  18. 18. The high voltage produces an electrically charged jet of polymer solution or melt, which dries or solidifies leaving a polymer fiber
  19. 19. the process was patented in 1934 by Formhals [2-4]</li></li></ul><li>ELECTROSPINNING<br />Figure 12. Schematic of Electrospinning Process<br /> Courtesy: www.che.vt.edu<br />
  20. 20. ELECTROSPINNING<br />Figure 13 The distribution of charge in the fiber<br />changes as the fiber dries out during flight<br />
  21. 21. Figure 14. Electrospinning set-up in the IMSP Physics <br />Division Materials Science Laboratory. <br />J.I.Zerrudo, E.A. Florido<br />
  22. 22.
  23. 23.
  24. 24. Taylor Cone<br /><ul><li>refers to the cone observed in electrospinning, electrospraying and hydrodynamic spray processes from which a jet of charged particles emanates above a threshold voltage
  25. 25. was described by Sir Geoffrey Ingram Taylor in 1964 before electrospray was "discovered“
  26. 26. 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</li></li></ul><li>Taylor Cone<br />Taylor angle. This angle is more precisely where is the first zero of (the Legendre polynomial of order 1/2).<br />two assumptions: <br />that the surface of the cone is an equipotential surface and <br />(2) that the cone exists in a steady state equilibrium<br />
  27. 27. Taylor Cone<br />Potential<br />Equipotential surface<br />The zero of the Legendre polynomial between 0 and pi<br />is 130.70990 which is the complement (supplement)<br />of the Taylor angle. <br />
  28. 28. Taylor Cone<br />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<br />
  29. 29. Classical liquid jet<br /> 0.1mm<br />Orifice – 0.1mm<br />Primary jet diameter ~ 0.2mm<br />Micro-jet diameter ~ 0.005mm<br /><ul><li>Gravitational, mechanical or
  30. 30. electrostatic pulling limited to
  31. 31. l/d ~ 1000 by capillary </li></ul> instability<br /><ul><li>To reach nano-range:
  32. 32. jet thinning ~10-3
  33. 33. draw ratio ~106 !</li></ul>NANOFIBRES T. A. Kowalewski, A. L. Yarin & S. Błoński, EFMC 2003, Toulouse<br />
  34. 34. Taylor Cone.<br />J.T.Garcia, E.A. Florido<br />
  35. 35.
  36. 36. Electrospinning<br />v=0.1m/s<br />moving charges e<br /> bending force on charge e<br />E ~ 105V/m<br />viscoelastic and surface tension resistance<br />Moving charges (ions) interacting with electrostatic field amplify bending instability, surface tension and viscoelasticity counteract these forces<br />NANOFIBRES T. A. Kowalewski, A. L. Yarin & S. Błoński, EFMC 2003, Toulouse<br />
  37. 37. Electro-spinning<br />Simple model for elongating viscoelastic thread <br />Stress balance:  - viscosity, G – elastic modulus stress, <br /> stress tensor, dl/dt – thread elongation <br />Momentum balance: Vo – voltage, e – charge, a – thread radius, h- distance pipette-collector <br />Kinematic condition for thread velocity v<br />Non-dimensional length of the thread as a function of electrostatic potential<br />NANOFIBRES T. A. Kowalewski, A. L. Yarin & S. Błoński, EFMC 2003, Toulouse<br />
  38. 38. Electro-spinning<br />bending instability of electro-spun jet <br />charges moving along spiralling path <br />E ~ 105V/m<br />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<br />NANOFIBRES T. A. Kowalewski, A. L. Yarin & S. Błoński, EFMC 2003, Toulouse<br />
  39. 39. Parameters<br />Molecular Weight, Molecular-Weight Distribution and Architecture (branched, linear etc.) of the polymer<br />Solution properties (viscosity, conductivity & and surface tension)<br />Electric potential, Flow rate & Concentration<br />Distance between the capillary and collection screen<br />Ambient parameters (temperature, humidity and air velocity in the chamber)<br />Motion of target screen (collector)<br />
  40. 40. Figure 14. Electrospinning set-up in the IMSP Physics <br />Division Materials Science Laboratory. <br />J.I.Zerrudo, E.A. Florido<br />
  41. 41. Fibers produced during electrospinning.<br />J.I.Zerrudo, E.A. Florido<br />
  42. 42. Fibers produced during electrospinning.<br />J.I.Zerrudo, E.A. Florido<br />
  43. 43. PVC Fibers produced during electrospinning.<br />J.T.Garcia, E.A. Florido<br />
  44. 44.
  45. 45. PVC Fibers produced during electrospinning.<br />J.T.Garcia, E.A. Florido<br />
  46. 46.
  47. 47. A.O.Advincula, E.A. Florido<br />
  48. 48.
  49. 49. J.C. La Rosa, E.A. Florido<br />
  50. 50. Electrospinning in MatPhy Lab, IMSP, UPLB <br />PEO microfibers, JennetteRabo, Maricon R. Amada, 2006<br />Polyaniline and Polyaniline/Polyester microfibers, Jefferson D. Diego, M.R.Amda, Emmanuel A. Florido, 2006<br />Polycaprolactone/Polyethylene Oxide nanofibers, Juzzel Ian Zerrudo, Emmanuel A. Florid0, 2008<br />Polycaprolactone (pcl)/Polyethylene oxide (peo)/iota carrageenan (ιcar) blends, Serafin M. Lago III, Teoderick Barry R. Manguerra, 2008.<br />
  51. 51. Electrospinning in MatPhy Lab, IMSP, UPLB <br />4. Poly (DL-lactide-co-glycolide)(85:15) PLGA and PLGA/Polycaprolactone (PCL) nanofibers, Christian Joseph Clarito, Emmanuel A. Florido, 2008<br />5. Polyvinyl Chloride (PVC) nanofibers from scrap PVC pipes, Ben Jairus T. Garcia, 2009<br />
  52. 52. Nanoresearch in UPLB: Physics Division, Institute of Mathematical Sciences and Physics, CAS<br />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<br />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<br />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<br />
  53. 53. 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<br />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<br />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.<br />
  54. 54. 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.<br />B.J.Garcia. Morphological and Molecular Characterization of Electrospun Polyvinyl chloride-PolyanilineNanofibers. IMSP, UPLB. April 2009. Undergraduate Thesis, Adviser: EAFlorido<br />J.D. Diego. Electrospinning of Polyaniline and Polyaniline/Polyester Based Fibers. IMSP, UPLB. November 2006.Undergraduate Thesis, Adviser: EAFlorido<br />

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