Huang Yongan

Morphology characterization and influential mechanism analysis of electrospun micro/nano-fiber

Electrospinning attracts more eyes of scientists with the continuous rapid development of nanotechnology. The key problem in application is to improve the controllability of electrospinning parameters, such as material parameters, processing parameters and environmental factors, which would affect the morphology and consistency of electrospun fibers. In this paper, the effects of material and process parameters, including molecular weight, concentration, applied voltage, electrode spacing, diameter of nozzle, and topography of electrospun polyoxyethylene (PEO) fibers are experimentally investigated. The results show that the evolution of the morphology experienced from spherical particle to fiber with beads, and to fiber with the concentration of PEO from 4% to 8% increasingly. The fiber with beads structure changed into uniform and smooth fibers with molecular weight of PEO from the 4×105 to 6×105. When the molecular weight of PEO further added, the morphology of PEO fibers is started to become uneven and jagged structure. When the conductivity of PEO rises from 151 to 355 μs/cm, the diameter is nearly five times thicker. As the applied voltage (25–30 kV) is increased, the diameter and spindle beads are increased at first and then decreased. With electrode spacing (15–25 cm) rising, PEO fibers become fine, but with more spindle beads. As nozzle diameter was increased from the 160 to 600 μm, the fibers is uniform and smooth at first, then form bonding structures. These results are able to guide the electrospinning technology in the biomedical, nano-devices and nano-manufacturing and other fields.

Recent advances in electrospun fiber basedelectronics

Electrospun fibers occupy an important position in fiber based electronics for their outstanding advantages, i.e. high length-to-diameter ratio, strong flexibility, high uniformity, controllable morphology, low cost and high efficiency in manufacturing. In this review, the development of electrospinning technique is firstly introduced, including design of multi-nozzle and special nozzle to improve efficiency and achieve special structure, regulation of solution and process parameters to deposit fibers with different morphologies, and development of fiber assembling and orientation to realize controllable direct-writing. Then recent researches on fiber based devices through electrospinning are reviewed, i.e. flexible sensor, super capacitor, lithium ion battery, dye sensitized solar cell, filed effect transistor and organic light emitting diode. Finally, the challenges and future directions of the field are prospected.