Fabrication of free-standing ordered fluorescent polymer nanofibres by electrospinning (original) (raw)
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A scanning tip electrospinning source for deposition of oriented nanofibres
Nanotechnology - NANOTECHNOL, 2003
We present a method for controlled deposition of oriented polymeric nanofibres. The method uses a microfabricated scanned tip as an electrospinning source. The tip is dipped in a polymer solution to gather a droplet as a source material. A voltage applied to the tip causes the formation of a Taylor cone, and at sufficiently high voltages, a polymer jet is extracted from the droplet. By moving the source relative to a surface, acting as a counter-electrode, oriented nanofibres can be deposited and integrated with microfabricated surface structures. For example, we deposited fibres of polyethylene oxide with diameters ranging from 100 to 1800 nm, with the diameter primarily depending on the concentration of the polymeric solution. In addition to the uniform fibre deposition, the scanning tip electrospinning source can produce self-assembled composite fibres of micro-and nanoparticles aligned in a polymeric fibre. We also deposited oriented conductive polymeric fibres of polyaniline an...
Polymer-Plastics Technology and Engineering, 2017
An innovative setup in which multiple electrodes, whose potentials can be switched on or off, was used for producing electrospun fibers. By controlling the activation time and sequence of switching between adjacent electrodes, the electrical field and thus the charge carrying fibers can be directed to different locations. It has been demonstrated that a variety of functionally graded architectures having preferred alignments can be produced. The simulation results point to possible mechanisms for directional deposition of fibers. The electrospun fibers can be varied in a controlled manner to produce mats containing random, aligned, or multidirectional nano-fibrous patterns.
Macromolecules, 2014
Polymer fibers are currently exploited in tremendously important technologies. Their innovative properties are mainly determined by the behavior of the polymer macromolecules under the elongation induced by external mechanical or electrostatic forces, characterizing the fiber drawing process. Although enhanced physical properties were observed in polymer fibers produced under strong stretching conditions, studies of the process-induced nanoscale organization of the polymer molecules are not available, and most of fiber properties are still obtained on an empirical basis. Here we reveal the orientational properties of semiflexible polymers in electrospun nanofibers, which allow the polarization properties of active fibers to be finely controlled. Modeling and simulations of the conformational evolution of the polymer chains during electrostatic elongation of semidilute solutions demonstrate that the molecules stretch almost fully within less than 1 mm from jet start, increasing polym...
2003-Polymer nanofibers assembled by electrospinning PDF
Electrospinning is a process by which polymer nanofibers (with diameter lower than 100 nm and lengths up to kilometres) can be produced using an electrostatically driven jet of polymer solution (or polymer melt). Simple alignment of electrospun nanofibers constructs unique functional nanostructures such as nanotubes and nanowires. Significant progress has been made in this area throughout the past few years and this technology has been exploited to a wide range of applications. Most of the recent work on electrospinning has focused either on trying to understand deeper the fundamental aspects of the process in order to gain control of nanofiber morphology, structure, surface functionality, and strategies for assembling them or on determining appropriate conditions for electrospinning of various polymers and biopolymers. ᮊ
Production of Highly Aligned Nanofibers via Two-Electrode Electrospinning
Advanced Science Letters, 2012
Two parallel metal electrodes were employed to collect highly aligned nanofibers in electrospinning process. The effect of three process parameters, i.e., the applied voltage, the nozzle-collector distance and the electrode gap, on the orientation angle of nanofibers was investigated by single-factor and orthogonal experiments, respectively. The results showed that the order of affecting the fiber orientation angle was ranked as the applied voltage > the spinning distance > the electrode gap. An CFD software package was used to numerically simulate the electric field in this process, giving a clear explanation of the nanofiber distribution.
Crimped polymer nanofibres by air-driven electrospinning
European Polymer Journal, 2007
Electrospinning is a well-known process for producing sub-micron scale polymer filaments through an electrostatic field. This paper presents a very simple ''confined'' air-driven electrospinning system, in which polyamide nanofibres are produced in the form of continuous crimped filaments. The reported system consists of a vertical cylinder with a weak tangential air-flow feeding from the top, placed between the capillary source electrode and the grounded target collector. The air-flow drives the polymer jet inside the electrostatic field, curls up the filament and reduces the deposition area on the collector surface. Numerical evaluations of both the electrostatic field and the air-flow path within the chamber are reported. The proposed configuration has been successfully tested electrospinning a solution of polyamide-6 in formic acid, varying the applied voltage and the distance between the electrodes. SEM observations of the electrospun fibres revealed that a large amount of crimped nanofibres was produced free from bead defects.
Long-Range Ordering of Highly Charged Self-Assembled Nanofilaments
Journal of the American Chemical Society, 2014
Charged nanoscale filaments are wellknown in natural systems such as filamentous viruses and the cellular cytoskeleton. The unique properties of these structures have inspired the design of self-assembled nanofibers for applications in regenerative medicine, drug delivery, and catalysis, among others. We report here on an amphiphile of completely different chemistry based on azobenzene and a quaternary ammonium bromide headgroup that self-assembles into highly charged nanofibers in water and orders into two-dimensional crystals. Interestingly small-angle X-ray scattering (SAXS) shows that these fibers of 5.6 nm cross-sectional diameter order into crystalline arrays with remarkably large interfiber spacings of up to 130 nm. Solution concentration and temperature can be adjusted to control the interfiber spacings, and addition of salt destroyed the crystal packing indicating the electrostatic repulsions are necessary for the observed ordering. Our findings here demonstrate the universal nature of this phenomenon in systems of highly charged nanoscale filaments.