OUTLINE:
• Introduction• Background
Apparatus Working principle Variables Fiber alignment Applications
• Future Research• Reference
Introduction
• Nanofibers are created by a process called electrospinning.
• Electrospinning is a major way to engineer (without self-assembly) nanostructures that vary in:
▫ Fiber Diameter
▫ Mesh Size
▫ Porosity
▫ Texture
▫ Pattern Formation
Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006. http://en.wikipedia.org/wiki/File:Taylor_cone_photo.jpg
An Example
• Take the distance between the Earth and the Moon, L, to be 384,400 km.
• It takes only x grams of a polymer fiber filament to make up this distance
• ρ = 1 g cm-3 and the fiber diameter d = 2r = 100 nm
• X = Vρ = πr2Lρ = π (50 nm)2
(380,000 km) (1 g cm-3 )
• ≈ 3 grams
Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.
Schematic Representation of the Reactive
Electrospinning Apparatus
• Fibers are irradiated with UV light during spinning in order to form crosslinked graft scaffolds
Electrospinning - Procedure• An electrostatic potential is applied between a
spinneret and a collector
• A fluid is slowly pumped through the spinneret.
• The fluid is usually a solution where the solvent can evaporate during the spinning.
• The droplet is held by its own surface tension at the spinneret tip, until it gets electrostatically charged.
• The polymer fluid assumes a conical shape (Taylor cone).
• When the surface tension of the fluid is overcome, the droplet becomes unstable, and a liquid jet is ejected
Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.
Electrospinning Polymers
• The small size between the fibers allows the capture of particles in the 100- to 300-nanometer range
• That is the same size of viruses and bacteria
• Used as air-filter: Airplanes, office, etc.
Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.
Polymer Solvent Concentration Potential Application
Nylon 6,6 Formic Acid 10 wt% Protective Clothing
Polyurethanes Dimethylformamide 10 wt% Protective Clothing
Polycarbonate Dichloromethane 15 wt% Sensor, Filter
Polylactic Acid Dichloromethane 14 wt% Drug Delivery System
Electrospinning Variables
Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.
Fibre alignment
• A cylinder collector with high rotating speed
• A thin wheel with sharp edge
• An auxiliary electrode/electrical field
Improvements and Further Research
• Develop more precise electrospinning techniques▫ Mechanisms of electrospinning
Growth rates
Bending Instability
▫ Producing nanofabrics with specific mechanical properties.
▫ Creating 3-dimensional shapes Capable of being used in controlled
release of drugs.
Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.
Improvements and Further Research
• Optimization of parameters
▫ Intrinsic properties of solution
Polarity, surface tension of solvent,
MW of polymer, etc.
• Safety
▫ Solvents
Dangerous to health and environment
"Electrospin Nanofibers for Neural Tissue Engineering."
http://www.rsc.org/ejga/NR/2010/b9nr00243j-ga.gif
References
• [1] Abdel-Ghani MS, Davies GA. Simulation of non-woven fibre mats and the application to
coalesces. Chemical Engineering Science 1985; 40(1):117–29.
• [2] Adanur S, Liao T. Computer imulation of mechanical properties of nonwoven
geotextiles in soil-fabric interaction. Textile Res J 1998; 68:155–62.
• [3] Angadjivand SA, Schwartz MG, Eitzman PD, Jones ME. US patent, 6375886. 2002.
• [4] Athreya SA, Martin DC. Impedance spectroscopy of protein polymer modified silicon
micromachined probes. Sensors and Actuators a—Physical 1999; 72(3):203–16.
• [5] Bognitzki M, Czado W, Frese T, Schaper A, Hellwig M, Steinhart M, et al.
Nanostructured fibres via electrospinning. Adv Mater 2001; 13:70–2.
• [6] Demir MM, Yilgor I, Yilgor E, Erman B. Electrospinning of polyurethane fibres.
Polymer 2002; 43:3303–9.
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