Nonwovens electrospun nanofibers

Ayutsede J et al (2005) Regeneration of Bombyx mori silk by electrospiiming. Part 3 characterization of electrospun nonwoven mat. Polymer 46(5) 1625-1634 Kwon IK, Matsuda T (2005) Co-electrospun nanofiber fabrics of poly(L-lactide-co-epsilon-caprolactone) with type I collagen or heparin. Biomacromolecules 6(4) 2096-2105... 

Hussain D., Loyal F, Greiner A., and Wendorff J. H., Structure property correlations for electrospun nanofiber nonwovens. Polymer, 2010,51, 3989-3997. 

Micrograph of electrospun nanofiber nonwoven web showing micropores with interconnected pore network. 

To the best of the authors knowledge to date, it is still not possible to obtain a single continuous electrospun nanofiber, let alone one with a constant diameter. The best that has been achieved so far are randomly oriented nonwoven mats that are not so attractive for use as composite reinforcements. Attempts have been made to align electrospun nanofibers, however, due to the complex nature of the polymer jet trajectory, this is difficult. Most of the techniques employed use a collector moving or rotating at high speeds... 

Fennessey, S. F., A. Pedicini, and R. J. Farris (2006). Mechanical behavior of nonwoven electrospun fabrics and yams. In Polymeric Nanofibers. ACS Symposium Series 918. Edited by D. H. Reneker and H. Fong. Oxford University Press (USA), p. 403. 

All these effects are classical ones yet have major impact on nanofiber properties and applications. These examples show that nanofibers and nonwovens composed of them display unique properties of functions already based on classical phenomena. This suggests that such fibers/non-wovens can be used with great benefits in various types of applications. The spectrum of applications that can be envisioned for electrospun nanofibers is extremely broad due to their unique intrinsic stmcture, surface properties and functions [67]. 

Fig. 1.14 Different aggregate structures of electrospun nanofiber (a) PAN nonwoven nanofibers, (b) PMIA alignment nanofiber, (c) PLLA patterning nanofiber, and (d) PA6 two-dimensional nanonets (a Reprinted with permission from Ren et al. [151]. 2012, Royal Society of Chemistry, b Reprinted with permission from Wang et al. [157]. 2013, Royal Society of Chemistry, c Reprinted with permission from Zhang and Chang [158]. 2007 WUey-VCH Verlag GmbH Co. KGaA, Weinheim. d Reprinted with permission from Wang et al. [160]. 2011, Roytd Society of Chemistry)...

Nonwoven mats of electrospun nanofibers can be further processed into scaffolds with complex architectures such as stacked arrays and tubular conduits. Stacked arrays of electrospun nanofibers are made of multiple layers of fibers that are sequentially deposited on top of one another. The main motivation for developing this type of scaffold is to mimic some natural tissue with respect to its biochemical, structural, and mechanical properties, as well as to enable the formation of multilayered tissues. Tubular conduits made of electrospun nanofibers are usually used for applications in vascular or neural tissue engineering as they resemble the hollow structures of these tissues (see Figure 9.1). Here we only focus on the fabrication methods for these scaffolds with complex architectures. 

Figure 9.4 Scaffolds of electrospun nanofibers with complex structures or architectures. (a) A multi-electrode collector where different pairs of electrodes were grounded sequentially (e.g.. 1/4. 2/5, and then 3/6) to produce a multi-layered scaffold- (b) SEM image of a tri-layered scaffold with the nanofibers in each layer rotated by 120°. (c) Encapsulation of cells in between nonwoven mats of nanofibers by alternating depositions of fibers and cells, (d) fluorescence micrograph showing a construct...

Kim K et al (2003) Control of degradation rate and hydrophilicity in electrospun nonwoven poly (D, L-lactide) nanofiber scaffolds for biomedical applications. Biomaterials 24(27) 4977 985... 

In this chapter, a novel approach is presented for determination of nanofiber diameter of electrospun webs. In this approach we have demonstrated the general applicability of a method using real webs, taking into account 5 real electrospun nonwoven webs, which were obtained by electrospinning of PVA. The application of image analysis has been reviewed and successfully applied using this new approach. 

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