Nanofiber mats

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. 

Vondran JL, Sun W, Schauer CL (2008) Crosslinked, electrospun chitosan-poly(ethylene oxide) nanofiber mats. J Appl Polym Sci 109(2) 968-975... 

Fig. 4 (a) Electrospinning setup with counter electrodes used to focus the area of fiber deposition, (b-e) Images of resultant nanofiber mats electrospun with (b) no auxiliary electrodes, (c) one auxiliary counter electrode, and (d, e) both counter and like electrodes with different separation distances between them [48]... 

A major limitation of the parallel plate technique is limited fiber density and mat thickness, as explained in Sect. 3.2.1. This problem can be overcome by utilizing other forces that are able to overcome the electrostatic repulsive force between nanofibers. Thick aligned nanofiber mats were fabricated across parallel plates when a magnetic field was used to attract fibers to a mesh across parallel plates [97]. Another technique utilized mechanical forces to assemble low density aligned fiber arrays into thicker constructs [98]. This technique used automated tracks to provide continuous mechanical assembly of fiber arrays, and allows theoretically infinite mat thicknesses. 

Rieger, K.A., Birch, N.P., Schiffman, J.D., 2013. Designing electrospun nanofiber mats to promote wound healing - a review. Journal of Materials Chemistry B 1 (36), 4531—4541. 

Figure 14.6 Sensing ofHCI and NH3 using PPy/carbon nanofiber composites (a) SEM image of the nanofiber mat and (b) TEM of a single composite nanofibers (c) responses of the composite nanocables (a and b) and bulk PPy (c and d) to NHj (a and c) and HC (b and d) (Reprinted with permission from Sensors and Actuators B Chemical, CO gas sensing from ultrathin nano-composite conducting polymer film byM. K. Ram, O. Yavuz, f. Lahsangah and M. Aldissi, 106, 2, 750-757. Copyright (2005) Elsevier Ltd)...

Unnithan, A.R. Barakat, N.A.M. Pichiah, RB.T. Gnanasekaran, G. Nirmala, R. Cha, Y.S. Jung, C.H. El-Newehy, M. Kim, H.Y. Wound-dressing materials with antibacterial activity from electrospun polyurethane-dextran nanofiber mats containing ciprofloxacin HCl. Carbohydr. Polym. 2012, 90 (4), 1786-1793. 

Meng W, Xing Z-C, Jung K-H, Kim S-Y, Yuan J, Kang 1-K, Yoon S, Shin H (2008) Synthesis of gelatin-containing PHBV nanofiber mats for biomedictil application. J Mater Sci Mater Med 19 2799-2807... 

Figure 15(b) shows the wide-angle X-ray diffraction (WAXD) profiles of as-spun P(3HB) nanofiber mats spun from 1 wt.% solution. In the profile before enzymatic degradation, diffraction peaks assigned to both a-form crystal with 2/1 helix conformation and p-form with planar zigzag conformation were observed at 2 = 19.6°. 

Polymer solution with concentration 15 wt. % was prepared by dissolving PAN in DMF. The PAN solution in DMF was loaded into a 1 ml syringe. A modified electro spinning system consists of two syringe pumps was used to produce bulky nanofiber mats. The experimental setup of electrospiiming has been shown in... 

Present experimental investigation was carried out for a wide range of rotation speed of collector. Table 1 represents the characteristics and transport properties of bulky nanofiber mats. Results indicate that bulk nanofiber mats have high porosity. Tnrrpasp in speed rotation of collector increases the density of nanofiber mats and decreases bulk porosity of nanofiber mats. Statistical analysis stresses on the significant reduction of the bulk porosity of nanofiber mats. 

TABLE 1 Characteristics and transport properties of bulk nanofiber mats. 

Rotation speed of collector (RPM)) Density of nanofiber mats (g/cm) Bulk porosUy (%) Air permeability (l/m sec) Moisture transfer (%)... 

FIGURE 4 Air permeability versus bulk porosity of nanofiber mats. 

FIGURE 5 Experimental results of the relative humidity of the nanofiber mats with different porosity, (a) 99.92% and (b) 99.42%. 

Electrospun nanoiiber mats by modified electospinning system have high porosity. Results show that the porosity of nanofiber mats increases by decreasing speed rotation of dmm. Air permeability and moisture transfer of nanofiber mats were reduced with reduction the porosity of nanofiber mats. Based on experimental results, moisture transfer behavior is influenced by nanofiber mats porosity. Bulk nanofiber mats with high rates of water vapor diffusion and low air permeability are promising candidates for protective clothing applications. 

Brunauer-Emmett-Teller Electrospinning Electrospun polylacticacid Nanofiber mats Nylon 6... 

Pol5mier nanofibers exhibit several properties making them favorable for different applications. Nanofibers have a high specific surface area due to their small diameters, and nanofiber mats can... 

The electric response of isolated PANI fibers to vapors of aliphatic alcohols depends on the laige surfece-to-volume ratio, the uniformity of diameter, and the quantity of active material. The sensor constructions are comparable to or faster than those prepared from nanofiber mats of the same polymer. Also, the sensors made from individual fibers exhibit larger responses, especialty for bigger alcohol molecules, and also show true saturation upon exposure and removal of the alcohol vapor. The response of sensors made from electrospun nanofibers to small alcohol molecules is opposite to that observed for cast nanofiber mats, which can be related to the doping process used in the preparation of the polymer in either case. ... 

Poly(3,4-ethylenediox5d hiophene3 (PEDOT) nanoiiber mats by electrospinning combined with in situ interfacial pol3mierization (Fig 5.11], The PEDOT nanofiber mats displayed good mechanical properties (tensile strength 8.7 0.4 MPa Young s modulus 28.4 ... 

MPa] and flexibility, which can almost be restored to its original shape even after serious twisting and crimping. Especially, from the results of the cellular morphology and proliferation of human cancer stem cells (hCSCs) cultured on the PEDOT nanofiber mats for 3 days, evidence was provided that the PEDOT nanofiber mats have similar biocompatibility to tissue culture plates (TCPs) combined with a high electrical conductivity of 7.8 0.4 S cm". ... 

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