TiO2/Polyvinyl Pyrrolidone (PVP) Hollow Fibers
Multicomponent fibers can be produced with special morphologies, such as side-by-side (bi/ tricomponent), coaxial, and triaxial, by use of special nozzles. Coaxial and triaxial morphologies are important for encapsulation of additives, drugs, particles, bacteria, viruses, catalysts, enzymes, etc., in the core of the fibers and for reinforcement purposes. For making these special morphologies, two or more spinning solutions are allowed to flow in special nozzles either with two chambers arranged side-by-side, separated by a membrane (side-by-side nozzle), or in coreeshell geometry (coaxial nozzle). The first coaxial fibers produced by electrospinning were shown by Greiner and Yarin and colleagues (Sun et al., 2003). In this work, polydodecylthiophene was used as the core material, while PEO was used as the shell. This method is also used for making hollow nanofibers with shells made of a stable inorganic/polymer composite or ceramic by electrospinning two liquids through a coaxial spinneret, followed by selective removal of the cores (Fig. 4.18) (Li and Xia, 2004). Such hollow nanofibers are promising candidates as nanoreactors for catalysis, for fabricating fluidic devices,
