Decorated nanofibers

The incorporation of nanofibers with smaller nanoparticles can be classified into two different categories, which also means two different approaches. The first one is to embed nanoparticles into nanofibers. In this case, the aim is to reinforce or functionalize nanofibers. The other one is the group of exocomposites or decorated nanofibers where nanopart-... 

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. 

Fig. 4 Functional decoration (F) of self-assembled nanofibers to mimic fibrillar structures of the ECM. The monodisperse nature of the building blocks and the precise assembly motifs lead to nanostructures with well-defined functional surfaces. Adjusting of these faces enables the generation of bioactivity by presenting biorelevant epitopes [88, 92, 105, 108, 116, 128]...

Zhang, Z. Wang, Z. Cao, S. W. Xue, C. Au/Pt Nanoparticle-Decorated Ti02 Nanofibers with Plasmon-Enhanced Photocatalytic Activities for Solar-to-Fuel Conversion. J. Phys. Chem. C, 2013, 117, 25939-25947. 

Chen X., Dong B., Wang B. B., Shah R, and Li C.Y., Crystalline block copolymer decorated, hierarchically ordered polymer nanofibers. Macromolecules, 2010,43,9918-9927, D01 10.1021/mal01900n. 

A conducting polymer, such as polyaniline, decorated with metallic or semiconducting nanoparticles furnishes an exciting system to investigate the prospect of designing device functionality directly into the material. A facile bulk synthesis method capable of producing high-quality polyaniline nanofibers, with... 

Recently, a non-volatile digital memory device was fabricated using PANI nanofiber (diameter ca. 30 nm) decorated with gold nanoparticles (diameter below 5 nm) [317]. As shown in Fig. 7a, the polymer memory device displayed bistable electrical behavior (ON/OFF states). The transition from the OFF state to the ON state was ascribed to an electric field-induced charge transfer between the PANI nanofibers and the gold nanoparticles. The write-read-erase cycle tests could also be performed more than seven times (Fig. 7b). 

Formaldehyde is one of the main pollutants in the atmosphere. In indoor air, formaldehyde mainly comes from decorating materials, paint, furniture glue, and chemical fiber carpets, and the concentration of formaldehyde is always relative low (<20 ppm). Even if the concentration of the formaldehyde is low, it can cause symptoms such as headache, nausea, coryza, pharyngitis, emphysema, lung cancer, and even death, so it is necessary to take effective measures for its removal. Adsorption by carbonaceous adsorbents is the most widely used method to purify the polluted air. Carbon nanostructure such a carbon nanofiber and fiber especially in activated form can be good adsorbents for formaldehyde [65]... 

Li, H.Y., Chang, C.M., Hsu, K.Y., Liu, Y.L. Poly(lactide)-functionalized and Fe 30 4 nanoparticle-decorated multiwalled caibon nanotubes for preparation of electrically-conductive and magnetic poly(lactide) films and electrospun nanofibers. J. Mater. Chem. 22, 4855 860 (2012)... 

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. 

Pham-Huu C, Keller N, Roddatis W, Mestl G, Schloegl R, Ledoux MJ. Large scale synthesis of carbon nanofibers by catalytic decomposition of ethane on nickel nanoclusters decorating carbon nanotubes. Phys Chem Chem Phys 2002 4 514-21. 

Figure 6.11 (a) Carbonized PAN nanofiber decorated by iron nanoparticles on its surface. Reproduced with permission from Hou and Reneker (2004). Copyright 2004. John Wiley and Sons, Inc. (b) Ti02/gold composite. Reproduced with permission from Li, D., et al. (2004b). Copyright 2004. Elsevier. 

Figure 6.12 Arrangement of capillary tips for concurrent electrospinning and electrospraying to obtain nanofibers decorated with nanoparticles. (Courtesy of RTI International.)...

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. 

Decoration of nanofiber surface Dong, H., et al. (2006) with nanoparticles. Synthesis and assembly of metal nanoparticles on electrospun poly(4-vinylpyridine) fibers and blend fibers. 

Gao J, Hu M, Dong Y, Li RKY (2013) Graphite-nanoplatelet-decorated polymer nanofiber with improved thermal, electrical, and mechanical properties. ACS Appl Mater Interfaces 5... 

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