Multi-coaxial Fibers by Multifluidic Coaxial Electrospinning
Once again, in 2010, Zhao’s group prepared coreeshell ultrathin fibers with a novel nanowire-inmicrotube structure by the multifluidic coaxial electrospinning approach (Chen et al., 2010). As shown on the left of Fig. 5.20, the spinneret was assembled by three coaxial stainless-steel capillaries, through which three selected fluids were fed to form a compound jet under a high electric field. The middle fluid served as a spacer to protect the inner and outer fluids from each other. The rectangular and circular insets show the configuration of the spinneret and the ideal structure of the collected fibers, respectively. The key step of this method for preparing nanowire-in-microtube fibers successfully is to use a designed compound spinneret and introduce an extra middle fluid to work as a spacer. In this case, highly miscible or microphase separation solution systems were harmonized and cojetted to sandwich ultrathin fibers. Fig. 5.20AeD show magnified cross-sectional SEM images of the sample, in which the fibers show a uniform morphology and continuous nanowire in the microtube. The author using this new method prepared inorganic TiO2 nanowire-in-microtube (NW@MT) structured fibers and organic PAN@PSNW@MT structured fibers. We believe that this method is an important extension of traditional coelectrospinning, and this special hollow cavity structure may introduce extra properties into the conventional coreeshell structure, which may have potential applications in fields such as optical applications, microelectronics, and others.