Fabrication and application of novel two-dimensional nanowebs via electrospinning

This chapter reviews our recent progress on the novel two-dimensional nanowebs by the optimization of processing parameters during electrospinning. Using high applied voltage and low relative humidity in chamber, the by-product of micro-sized defect films can be splitted into nanowebs due to the fast phase separation of the charged droplets which flight with high moving speed in electric field from capillary tip to collector. The electrospun fibers act as a support for the “fishnet-like” nanowebs comprising interlinked one-dimensional nanowires. The average diameter of the nanowires contained in typical nanowebs is about one order of magnitude smaller than that of conventional electrospun fibers. Nanowebs together with common electrospun nanofibers can be assembled into a three-dimensional fibrous mat. So far, nylon-6, polyacrylic acid (PAA), poly(vinyl alcohol) (PVA)/SiO₂ nanoparticles, and PVA/zinc acetate have been found to have the possibility forming nanowebs. The formation, morphology, and area density of the nanowebs in electrospun fibrous mats are strongly affected by the applied voltage, ambient relative humidity, kinds of solvents, solution concentration and conductivity, and distance between capillary tip to collector. The expanded applications of electrospun fibers are expected due to the formation of nanowebs, such as the nano-sized controllable filters, high efficient catalysts, catalyst supporter, and sensors. The preliminary data showing that the sensitivity of PAA nanowebs to ammonia is 2.5 times higher than that of electrospun PAA nanofibers. Additionally, PAA nanowebs show much quicker absorption speed and larger capacities than that of PAA nanofibers during the ammonia absorption test.