Electrospinning polymer properties

Electrospinning can create surface textures needed for superhydrophobicity. Electrospinning is a widely used technique to make ultra-thin polymer fibers. In this process, a polymer solution is charged in a capillary tube and electrically biased with respect to a grounded collector surface located 10 cm from the needle. The polymer solution is then ejected from the capillary into a jet form and the solvent evaporates leaving polymer fibers. By electrospinning polymers with hydrophobic properties, one can easily produce superhydrophobic fiber mats on the collector [89-92]. Of course, the electrospinning can also be used to make porous fiber mats... 

Although a random deposition of electrospun fibres gives a nonwoven fibre sttucture, the web morphology varies depending on the polymer properties and the operating conditions. Usually, the nanofibres are accumulated by a simple physical interaction and the fibres do not bond with each other. However, when the electrospinning distance is very short, the solvent has insufficient... 

In order to improve the properties and the spinnability, fibroin sometimes has been electrospun together with other natural or synthetic polymers (Jin et al., 2002 Park et al., 2004, 2006 Wang et al., 2004, 2006). For instance, Jin et al. (2002) developed an aqueous process for silk electrospinning in combination with PEO. More recently, Cao (2008) used PVA/Silk Fibroin (SF), Gelatin/SF, and Hydroxyapatite (HAP)/SF to produce double-layered (core-shell) nanofibers (mats) by coelectrospinning. 

Sukigara, S., Gandhi, M., Ayutsede, J., Micklus, M., and Ko, F. "Regeneration of Bombyx mori silk by electrospinning - part 1 Processing parameters and geometric properties". Polymer 44(19), 5721-5727 (2003). 

S. Sukigara, M. Gandhi, J. Ayutsede, M. Micklus, F. Ko. 2003. Regeneration of Bombyx mori silk by electrospinning part FProcessing Parameters and Geometric Properties. Polymer, 44.pp. 5721-5727. 

The last method to be discussed, which is used to form polymer/ceramic composites by electrospinning, is extremely different to the methods previously described, but worth mentioning. Zuo et al. [129] used a method to create a composite scaffold that is actually the reverse of what most people are doing. Instead of mineralizing the nanofibers, Zuo et al. actually incorporated electrospun polymer nanofibers into a ceramic bone cement in order to form a composite scaffold. It was found that by incorporating electrospun nanofibers into the cement, the scaffold became less brittle and actually behaved similarly to that of a ductile material because of the fibers. Composite scaffolds with different polymers and fiber diameters were then tested in order to determine which scaffold demonstrated the most ideal mechanical properties. However, no cell studies were conducted and this method would most likely be used for a bone substitute instead of for bone regeneration applications. 

In addition to the process parameters, a number of system parameters play an important role in fiber formation and the obtained structure. System parameters include molecular weight, molecular weight distribution, polymer architecture, and solution properties. Solution properties play a particularly important role. In relation to their impact on the electrospinning process, these factors can be ranked as follows polymer concentration, solvent volatility, and solution conductivity. 

Polymer-supported Ag nanoparticles have been widely investigated and provide potential applications as catalysts, photonic and electronic sensors, wound dressings, body wall repairs, augmentation devices, tissue scaffolds, and antimicrobial filters [15-22]. For these applications, Ag nanoparticles have to be supported in a biocompatible polymer system [23-26]. The electrospinning technique has often been adopted for the incorporation of Ag nanoparticles into polymer porous media. In this chapter, we review the preparation methods and properties of Ag nanoparticles incorporated into polymeric nanofibers and their applications in the fields of filtration, catalysis, tissue engineering and wound dressing. 

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