Electrospinning: Not just for DJs anymore

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Electrospinning Not just for DJs anymore

• Kendra A. Erk
• Advisor Dr. Jeffrey P. Youngblood

REU Final Presentation August 5, 2004
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Presentation Outline

• Introduction to electrospinning and conducting
  polymers
• Electrospinning observations and results
• Resistance and resistivity analysis
• Summary and future work

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Electrospinning Basics

• Process by which high static voltages are used to
  produce fibers from a polymer solution
• Micron to submicron diameter
• Fibers have huge SAVolume ratio
• Applications filters, wound dressing, composite
  reinforcement

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ES Process

• Polymer solution with sufficient viscosity
• High voltages applied to solution
• Fibers deposit on collection target

Rutledge Group, MIT
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ES Apparatus
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Conducting Polymers

• synthetic metals which combine chemical and
  mechanical properties of polymers with electronic
  properties of metals
• Easy and inexpensive to make, flexible,
  light-weight, and stable
• Replace metals used in some applications like
  molecular wires in nanostructures

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Polymers v. Metals
N.J. Pinto
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My Research Direction

• Original Project Goals
• Electrospin conducting fibers from water-soluble
  conducting polymers or conducting/structural
  polymer blends
• Polyaniline sulfonic acid, 5 wt in water (PAS)
• Polyvinyl alcohol (PVA)
• Examine the effect of polymer blending on
  spinning parameters and conductivity

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Conducting Polymer PAS

• Early Spinning
• Spun conducting polymer as purchased
• Sufficient viscosity
• Result spray, fibrous chunks

5 wt polyaniline sulfonic acid in water
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Structural Polymer PVA

• Poly(vinyl alcohol)
• Soluble in water
• Semicrystalline
• Chemically and thermally stable
• Highly biocompatible, nontoxic
• Ribbon fibers formed at low PVA concentrations

1.04 wt PVA in water, 14.96 kV at 26 cm
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Structural Polymer PVA
5.36 wt PVA, 17.55 kV, 26.5 cm
7.43 wt PVA, 16.68 kV, 26 cm

• Optimal concentration 7.45 wt PVA in water
• Result smooth fibers, d 0.6 3 microns

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Polymer Blends PAS PVA
14 PASPVA
11.5 PASPVA

• PASPVA ? 10.5 to 14 in 0.5 PVA increments
• Results visible fibers, brown/yellow in color,
  0.6-3 micron diameters, best spun by drops

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Polymer Blends PAS PVA
11.5

• Best spinning from 11-12.5
• At low PVA conc. fibers bridge to frame, high
  fiber yield
• At high PVA conc. fibers mat to slide, low fiber
  yield

13.5
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Resistance Analysis of PAS/PVA Blends

• MPJA 9903 Autoranging Multimeter (max 30 MO)
• 1x1 cm thin films
• Electrospun fibers

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Summary

• Water-soluble conducting polymer PAS blended with
  PVA was successfully electrospun
• PAS/PVA high yield, smooth, 0.6-3 micron fibers
• For resistance testing, thin films and fibers
  were produced from the various PAS/PVA blend
  ratios
• Resistivity increased with increasing PVA
  concentrations
• Solutions with PVA lt 67 wt produce fibers and
  films more conducting than silicon, a
  semiconductor

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Future Work

• Try other structural polymers
• Refine electrospinning techniques (capillary
  pump, charged box)
• Isolate specific fibers and use SEM to determine
  more accurate diameters and cross-sectional areas
• Photovoltaic applications

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Acknowledgements

• Dr. Youngblood and the Y-team
• Ben Eick, John Howarter, Phil Sellenet, Allen
  Mackey, Alicia Certain
• Dr. Kvam and Dr. Trice
• Fellow REU students
• NSF

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Questions?