1 / 12

Polypyrrole /polyurethane ( PyPU ): a conducting polymer- elastomer composite

Polypyrrole /polyurethane ( PyPU ): a conducting polymer- elastomer composite . Craig Milroy (group presentation #5) 5/24/2011. Electrospun Nanofibers. Ideal for applications that require large surface area-to-volume battery separators membranes tissue engineering scaffolds catalysts

elysia
Télécharger la présentation

Polypyrrole /polyurethane ( PyPU ): a conducting polymer- elastomer composite

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Polypyrrole/polyurethane (PyPU): a conducting polymer-elastomer composite Craig Milroy (group presentation #5) 5/24/2011

  2. ElectrospunNanofibers Ideal for applications that require large surface area-to-volume • battery separators • membranes • tissue engineering scaffolds • catalysts ***Controlled porosity*** Li, Xia. Adv Mat 2004; 16(14): 1151-1170.

  3. Research Objective: • identify appropriate solvent for electrospinningPyPU Methods: • synthesizePyPU (1:5 wt/wt; emulsion polymerization) • prepare 8-20 wt% solutions: • CHCl3 • DMF/THF (100/0, 70/30, 50/50, 30/70, 0/100)* • HFIP *Khil, Cha, Kim, Bhattarai. ElectrospunNanofibrous Polyurethane Membrane as Wound Dressing. JBMR 2003, 67B:675-679.

  4. Electrospinning Apparatus Taylor Cone Stable Jet Bending Instability Adapted from: Bhardwaj, 2010 SEM image from Xia, 2004

  5. videos http://www.scivee.tv/node/26466

  6. Results (THF):

  7. Results (HFIP):

  8. Rayleigh Instability (revisited) • Governing Equations: • Conservation of Mass (Continuity) • Conservation of Momentum (Navier-Stokes) • Consider a sinusoidal perturbation to an axisymmetric cylindrical jet: • k : wavenumber ( ) • ω : growth rate of perturbation • ω > 0 instability grows • ω < 0 instability decays • ω = 0 standing wave • Dispersion Relationship a η ω Hohman 01

  9. Linear Stability Analysis of Jet Dispersion relations when > 0 • Dispersion Relation: • Apply similar perturbations • Equation is cubic, thus three branches • Two destabilizing branches: • Rayleigh mode – is suppressed as electric field is increased • Conducting mode – is enhanced as electric field is increased. • Destabilizing if Re ω > 0 Hohman 01

  10. Summary • Both THF and HFIP appear to be promising solvents • Next steps: • More thorough characterization of starting solution: (viscosity, surface tension) • More thorough investigation of electrospinning parameters: (applied voltage, working distance, field strength) • Modify electrospinning configuration (vertical) • Investigate parameter ranges for which Raleigh instability is suppressed (as a function of parameter values)

  11. QUESTIONS?

  12. References • Bhardwaj N, Kundu S. Electrospinning: A fascinating fiber fabrication technique. Biotechnology Advances 2010; 28:325-347. • Hohman MM, Shin M, Rutledge G, Brenner MP. Electrospinning and electrically forced jets. I. Stability Theory. Physics of Fluids 2001; 13:2201-2220. • Reneker DH, Yarin AL, Fong H, Koombhongse S. Bending instability of electrically charged liquid jets of polymer solutions in electrospinning. Journal of Applied Physics 2000; 87:4531-4547. • Xia, 2004.

More Related