Double-shelled coaxial core-shell

Modifications of the electrospinning technique have been proposed in order to obtain oriented fibers or core-shell nanofibers and nanotubes. The coelectrospinning allows the preparation of core-shell fibers or tubes different polymeric solutions can be injected thought concentric annular needles and electro-spun through the formation of a double Taylor cone. The mixing of the two solutions can be avoided by means of a very fast electrospinning process by which coaxial nano and micro fibers can be obtained with a proper choice of the polymeric materials, the inner core can be removed and nanotubes isolated [328], as shown in Fig. 1.30. 

Figure 9.5 (a) The coaxial double-capillary tip arrangement used in electrospinning core-shell nanofibers. Reprinted with permission from Sun et al. (2003). Copyright 2003. John Wiley Sons, (b) A coaxial tip design used by Larsen et al. (2003) for olive oil-water (liquid-liquid) coaxial jets. The inset shows the double-layered Taylor s cone. Reprinted with permission from Larsen et al. (2003). Copyright 2003. American Chemical Society. 

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