Continuous spinning of polymer nanofibers with uniform diameters using an anodic porous alumina spinneret with holes of different diameters

Monodisperse polymer nanofibers smaller than 50 nm were prepared via continuous spinning using anodic porous alumina as a spinneret. In the nanofiber spinning method using a spinneret, the diameter of the resulting nanofibers depends on the diameter of the spinneret aperture. Therefore, in order to spin fine nanofibers, it is necessary to use a spinneret with a fine aperture. However, as the aperture size decreases, the pressure loss in the direction of depth in the spinneret increases, making it difficult to extrude highly viscous polymer solutions. To overcome this problem, we have developed new types of anodic porous alumina spinnerets with holes of different diameters in the direction of its thickness. In the spinneret with holes of different diameters, the layer with fine holes acts as an aperture layer for extrusion of the polymer solution, and the layer with larger holes acts as a support layer. By adopting the spinneret with two-layered hole array structures, we can realize extrusion with low-pressure loss and a reduced hole diameter. Using this new type of spinneret, we can achieve the formation of extremely fine nanofibers of similar to 12 nm diameter. We also prepared fine carbon nanofibers through carbonization of the obtained nanofibers as a precursor. The obtained nanofibers are expected to be used in various applications.