Electrospun polymeric fibers

Jaeger et al. studied the morphological characteristics of electrospun polymeric fibers in the diameter range of 200-800 nm (Jaeger et al. 1998). Koombhongse et al. spun different fibers and reported flat ribbon I i ke structures and branched fibers (Koombhongse et al. 2001). The electrospun fibers were between 1 and 3 pm in diameter. 

To meet these potential applications, a rich variety of electrospun polymeric fibers with diameters ranging from several tens to several hundreds nanometers are now being fabricated and studied for suitability. Unfortunately, most as-spun polymer nanofibers are chemically inert and do not have any specific functions. From the above descriptions, one can see that to realize these applications, there is a need to modify the polymer nanofibers to incorporate new functionalities on the surface. This in return enhances its property or produces unique surface properties required by the various applications. For example, for the nanofibers to be used as drug delivery carriers, drug molecules must be hybridized with the polymer nanofiber for the nanofibers to be used as an affinity membrane for antibody purification, protein A or G should be covalently bonded on the nanofiber surface for the nanofiber mesh to be used as protective cloth, capture agents need to be introduced on the nanofiber surface to capture and decompose molecules of toxic gas. 

Normal transmission IRLD can also be used to characterize polymeric fibers, although scattering can induce sloping baselines. Raman spectroscopy then becomes a convenient alternative. Rutledge et al. have recently probed the orientation in electrospun nanofibers composed of a core of Bombyx mori fibroin and an outer shell of poly (ethylene oxide) [24], The orientation values were low, less than 0.1, as is often the case in electrospun fibers. 

When the electrospun oxidant fibers are exposed to Py monomer vapors, redox reaction occurs where Py is oxidized, while FeCl3 is reduced. During the Py vapor diffusion, which adds moisture to the fibers, the longer the polymerization time, the more compact the fibers (Fig. 4.12). 

Rather than drag coating onto electrospun surface, Kenawy et al. [51] have examined the behavior of nanofibers composed of PLA and poly (ethylene-acetate co-vinyl) (PEVA) with incorporated drag. The fibers were prepared by dissolving the polymer with tetracycline hydrochloride drag, thereby producing polymeric fibers. This experimentation demonstrates a constant drug release over 5 days from the polymer nanofibers in electrospun PEVA and 50/50 PLA/PEVA mats. 

Tsai P P, Ghen W and Roth J R (2004) Investigation of the fiber, bulk, and surface properties of meltblown and electrospun polymeric fabrics. Intern Nonwovens J 13 17-23. 

Electrospinning process is a very useful technique used to fabricate suitable polymeric fibers with small diameter [137] due to the possibility of producing three dimensional structures that enable the development of advanced materials with sophisticated applications [138-140], However, thermal stability and decomposition kinetic of nanofibers may be different from micron-sized particles of a same polymer. In particular, in this chapter, we focus the attention on the electrospun fibers of PU and of PU-based... 

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