Composite nanofibers nanofiber- nanoparticle

Fig. 2 (a, b) TEM images of AgCl/PVP nanocomposite fibers, (c) Electron diffraction patterns of composite nanofibers, (d) Size distributions of AgCl nanoparticles in composite nanofibers... 

A gas-solid reaction was further introduced to the electrospiiming technique to incorporate semiconductor nanostructures into polymer nanofibers with better dispersion. The production of well-dispersed PbS nanoparticles in polymer fiber matrices has been achieved by this method (Lu et al., 2005). First, metal salt and polymer were codissolved into one solvent to make a homogeneous solution. Then the above solution was electrospun to obtain polymer/metal salt composite nanofibers. The composite nanofibers were finally exposed to HaS gas at room temperature to synthesize PbS nanoparticles in situ in polymer nanofibers. 

In addition to in situ reduction by the CPs, metal nanoparticles can also be synthesized on the surface of the CPs via a reduction process in the presence of other reducing agents. Yan and co-workers prepared PANI/Pt composite nanofibers by reducing a Pt salt with ethylene glycol on the surface of PANI nanofibers [78]. The diameter of PANI nanofibers was about 60 nm, and that of as-synthesized Pt nanoparticles (PtNPs) was only about 1.8 nm as calculated from X-ray diffraction (XRD) data. The small size of PtNPs on the CP matrix enhanced the electrocatalytic activity for the methanol oxidation reaction. 

GOX could also be incorporated into aligned CNT/PPy composite nanofibers with Fe nanoparticles on the tip of CNTs [161]. Inclusion of Fe nanoparticles was the key factor to reduce the potential of the redox reaction of H O. A near linear increase in the current up to 20 mM... 

Electrospinning is an efficient technique for the fabrication of polymer fibers. Various cationic polymers have been successfully electrospun into ultrafine fibers, mostly from solvent solutions but some in melt form. Composite nanofibers of biodegradable poly(D,L-lactic-co-glycolic acid) (PLGA) encapsulating chitosan/siRNA nanoparticles (NPs) were prepared by electrospinning (Figure 16.5). ... 

Xie Y, Sun L, Wang C, Wang S, Xu G, Zhang J, et al. Preparation and photolumines-cent characterization of poly(pheny-lene vinylene)/TI02 nanoparticles composite nanofibers by one-step electrospinning. J Appl Polym Sci 2012 126(3) 1061-8. 

Liu L, Li B, Zhang J, Qin R, Zhao H, Ren X (2009) Electrospinning preparation and characterization of a new kind of composite nanomaterials raie-dimensitmal composite nanofibers doped with Ti02 nanoparticles and Ru(II) complex. Mater Res Bull 44 2081-2086... 

Composite nanofibers incorporated with smaller nanoparticles... 

Another group of composite nanofibers are decorated or exocomposite nanofibers which are particularly developed for biomedical and sensor applications. The nanoparticles are located at the surface of nanofibers, which can lead to ultra-fast drug release, but do not play reinforcing role. 

Assuming the nanoparticles to be fiiUy within the fiber, the term composite nanofiber implies a nanocomposite nanofiber, as microparticles cannot be accommodated within a nanofiber. It is therefore convenient to use the simpler term in referring to these. 

A great majority of the composite nanofibers are of a conventional structure where tiie nanoparticles are contained within tiie matrix of the nanofiber. However, anotiier class of composites (referred to here as exocomposites for convenience) consists of the nanoparticles partially embedded in and decorating the surface of the nanofibers. These might be prepared by posttreatment of tiie nanofiber or by electrospinning in a dusty environment, allowing nanoparticles to come into contact witii the moist elongating jet. These decorated nanofibers may be of interest in applications such as the rapid delivery of poorly soluble bioactive materials via a water-soluble nanofiber exocomposite mat, in optical devices, or as chemical/biological sensors. These will be briefly discussed at tiie end of the chapter. 

The technique yielded composite nanofibers with 50mgPd/g polymer with nanoparticle diameters in the range of 10-60nm. The catalytic effectiveness of Pd in the composite nanofiber mat for hydrogenation reaction of dehy-drolinalool (3,7-dimethyloct-6-ene-l-yne-3-ol) was assessed to be 4.5 times higher than that for a conventional Pd/alumina catalyst. Silver nanoparticles... 

Coaxial spinning can also be used to form polymer-particle composite nanofibers as discussed in Chapter 6. Li et al. (2005a), in their research on decorating the interior of hoUow nanofibers with nanoparticles, used this technique very effectively. The core fluid used was a ferrofluid of magnetic iron oxide particles and the shell layer was a mixture of poly(vinyl p5u-olhdone)/ titanium isopropoxide. Extraction of the core phase of the core-shell nanofibers with octane yielded hollow, magnetically susceptible nanofibers, with their interiors decorated with oxide nanoparticles. 

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