Poly average fiber diameter

Figure 17.7 (A) Cyclic voltammogram of catechol on a platinum electrode. (B) Effect of poly(aniline-co-o-aminophenol) fiber diameter on the electrochemical oxidation of catechol, at a scan rate of 60 mV Average fiber diameter ( ) 70 nm, (2) 90 nm, (3) 100 nm, (4) 107 nm, in a solution consisting of 5 mM catechol and 0.3 M Na2S04 with pH 5.0. (Reprinted with permission from Electrochimica Acta, Poly(aniline-co-o-aminophenol) nanostructured network Electrochemical controllable synthesis and electrocatalysis byShaolin Mu, 51, 17, 3434-3440. Copyright (2006) Elsevier Ltd)...

This observed system-dependence of the value of [t/Jc is to be expected, because the average chain conformations, and therefore the entanglement of chains, depends on solvent quality. Poly(ethylene glycol) (PEG) electrospun from solutions of [iq]c 10 but made up in different solvents yielded very different average fiber diameters, partly because the solvent characteristics also play a role in determining fiber quality (Son et al. 2004d). 

Figure 7.9 Nanofiber mat of poly( -caprolactone) (PCL) prior to seeding with cells, demonstrating the high degree of porosity. Average fiber diameter d = 400 200 nm. Reproduced with pennission from Yoshimoto et al. (2003). Copyright 2003. Elsevier.

Figure 3 Current-voltage characteristics of an isolated doped poly aniline nanofiher at 30 OK in a vacuum of W Torr. The fiber resistance was 114 MO and the conductivity was 10 S/cm. Inset SEM image of an isolated electrospun fiber making contacts to two gold leads. The lead separation was 2 jum and the average fiber diameter was 150 nm.

CNs have also been incorporated into poly(ethylene-co-vinyl acetate) (EVA) to make EVA/CN composite membranes. Elanthikkal et al. [59] investigated the effect of CN on barrier properties of EVA membranes. Cellulose from banana waste was exposed to alkali treatment, bleaching, and acid hydrolysis to obtain CNs. The resulting CNs were approximately 300 nm long with an average fiber diameter of 30 nm. Tetrahydrofuran was used as solvent to dissolve EVA and to disperse aqueous suspension of CNs. Membranes were obtained by casting-evaporation method. Cellulose fibers were exposed to alkali treatment and bleaching followed by acid hydrolysis. An aqueous suspension obtained after dialysis and ultrasonication was... 

Shih [85] prepared two composite nanofibrous membranes of PVDF and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) by electrospinning to be employed in a DCMD. Using SEM observations, a porosity analyzer technique, and contact angle measurement, it was found that the nanofibrous membrane with an average fiber diameter of 170 nm was the best membrane to be applied in DCMD systems. It was observed that over a period of 12 h, the permeate flux of the PVDF-HFP composite membrane was 4.28 kg m" h", which was significantly higher than the PVDF membrane and even higher than the PTFE commercial membrane. 

Nanofibers based on poly(vinyl alcohol) as the matrix, and nanocrystals of a-chitin (ca. 31 nm in width and ca. 549 nm in length) as the nanofiller were prepared by Junkasem et al. [51]. The average diameters of the electrospun fibers ranged between 175 and 218 nm. The addition of increasing amounts of the whiskers caused the crystallinity of poly(vinyl alcohol) within the nanocomposite materials to decrease and the glass transition temperature to increase. 

Dong and Jones Jr. reported on the preparation of submicron electrically conductive polypyrrole/poly(methyl methacrylate) coaxial fibers and conversion to polypyrrole tubes and carbon tubes [47]. In this study, PMMA fibers with an average diameter of 230 nm were initially fabricated by electrospinning as core materials. The PMMA fibers were subsequently coated as templates with a thin layer of PPy by in situ deposition of the conducting polymer from aqueous solution. Hollow PPy nanotubes were produced by dissolution of the PMMA core from PPy/PMMA coaxial fibers. Furthermore, high temperature (1000 °C) treatment under an inert atmosphere can be used to convert PPy/PMMA coaxial fibers into carbon tubes by complete decomposition of the PMMA fiber core and carbonization of the PPy wall (Figure 4.13). 

Chuangchote et aL (2008) fabricated ultrafine poly[2-methoxy-5-(20-ethylhexyloxy)-l,4-phenylenevinylene]/poly(vinyl pynolidone) (PVP) composite fibers for conductive nanofibers by electrospinning blended solutions in a mixed solvent of chlorobenzene and methanol. The average diameter of the eiectrospun fibers was found to decrease with the reduction of the PVP concentration and/or the addition of the volatile organic salt, pyridium formate. 

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