Nanofiber-Nanoparticle Composites

Sputter coating is a particrrlarly convenient means of decorating the surface of fibers. A DC sputter coater using a high-prrrily silver target, for instanee. 

A similar technique was used by Min et al. (2004d) to electrospin copolymers of lactide with glycolide (PLGA) nanofibers from hexafluoroisopropa-nol (HFP) solvent from one capillary tip and regenerated chitin in formic acid electrosprayed from a separate tip, onto the same grounded collector drum. In this case, however, both electrospinning solutions carried a positive charge. 

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Fig. 5.3 Schematic configuration of a DSSC with Ti02 nanofiber-nanoparticle composite acting as an innovative photoanode (Reproduced from Joshi et al. [45] by permission of The Royal Society of Chemistry)...

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. 

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. 

Gomathi P, Ragupathy D, Choi JH, Yeum JH, Lee SC, Kim JC, Lee SH, Ghim HD. Fabrication of novel chitosan nanofiber/gold nanoparticles composite towards improved performance for a cholesterol sensor. Sens Actuators B. 201T,153(l) 44-9. 

Carlberg B, Ye LL, Liu J (2011) Surface-confined synthesis of silver nanoparticle composite coating on electrospun polyimide nanofibers. Small 7 3057-3066... 

Rim JR, Ahn H (2008) Fabrication and characterization of polystyrene/gold nanoparticle composite nanofibers. Macromol Res 16 163-168... 

The polymer resulting from oxidation of 3,5-dimethyl aniline with palladium was also studied by transmission electron microscopy (Mallick et al. 2005). As it turned out, the polymer was formed in nanofibers. During oxidative polymerization, palladium ions were reduced and formed palladium metal. The generated metal was uniformly dispersed between the polymer nanofibers as nanoparticles of 2 mm size. So, Mallick et al. (2005) achieved a polymer- metal intimate composite material. This work should be juxtaposed to an observation by Newman and Blanchard (2006) that reaction between 4-aminophenol and hydrogen tetrachloroaurate leads to polyaniline (bearing hydroxyl groups) and metallic gold as nanoparticles. Such metal nanoparticles can well be of importance in the field of sensors, catalysis, and electronics with improved performance. 

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