Bending instability of electrically charged liquid jets of polymer solutions in electrospinning

Reneker, Darrell H.; Yarin, Alexander L.; Fong, Hao; Koombhongse, Sureeporn

doi:10.1063/1.373532

Cited by 2,226 publications

(1,796 citation statements)

References 21 publications

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“…25,31 In this work, a solution of 8 wt% nylon 6 (Aldrich catalog number: 181110, weight-average molecular weight M w = 10,000 g/mol) in 1,1,1,3,3,3-hexafluoro-2-propanol (Aldrich) was prepared at room temperature, and a specially designed spinneret was used for conducting electrospinning. The spinneret consisted of a high-density polypropylene tube (an inner diameter of approximately 1.0 inch) and a stainless steel hemispherical head which had an orifice of 0.4 mm diameter at the center).…”

Section: Experimental Sample Preparationmentioning

confidence: 99%

Crystalline Morphology and Polymorphic Phase Transitions in Electrospun Nylon-6 Nanofibers

et al. 2007

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Uniform nylon 6 nanofibers with diameters around 200 nm were prepared by electrospinning. Polymorphic phase transitions and crystal orientation of nylon 6 in unconfined (i.e., as-electrospun) and a high T g (340 °C) polyimide confined nanofibers were studied. Similar to melt-spun nylon 6 fibers, electrospun nylon 6 nanofibers also exhibited predominant, meta-stable γ crystalline form, and the γ-crystal (chain) axes preferentially oriented parallel to the fiber axis. Upon annealing above 150 °C, γ-form crystals gradually melted and recrystallized into the thermodynamically stable α-form crystals, which ultimately melted at 220 °C. Release of surface tension accompanied this meltrecrystallization process, as revealed by differential scanning calorimetry. For confined nanofibers, both the melt-recrystallization and surface tension release processes were substantially depressed; γ-form crystals did not melt and recrystallize into α-form crystals until 210 °C, only 10 °C below the T m at 220 °C. After complete melting of nano-confined crystals at 240 °C and recrystallization at 100 °C, only α-form crystals oriented perpendicular to the nanofiber axis were obtained. In the polyimide-confined nanofibers, the Brill transition (from the monoclinic α-form to a high temperature monoclinic form) was observed at 180-190 °C, which was at least 20 °C higher than that in unconfined nylon 6 at approximately 160 °C. This, again, was attributed to the confinement effect.

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Section: Experimental Sample Preparationmentioning

confidence: 99%

Crystalline Morphology and Polymorphic Phase Transitions in Electrospun Nylon-6 Nanofibers

et al. 2007

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“…During electrospinning, adequate electro-tocollector distance is required to allow solvent to evaporate and nanofibers to become thinner via the whipping and splitting processes. 25 NFES takes the advantage of a stable liquid jet region immediately outside the spinneret for position controllable deposition by shortening the electrodeto-collector distance. At the same time, an electrode with a fine tip is introduced to generate (1) intensified electrical field to activate electrospinning, and (2) small-diameter liquid jets in the stable region.…”

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confidence: 99%

Near-Field Electrospinning

et al. 2006

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A near-field electrospinning (NFES) process has been developed to deposit solid nanofibers in a direct, continuous, and controllable manner. A tungsten electrode with tip diameter of 25 µm is used to construct nanofibers of 50−500 nm line width on silicon-based collectors while the liquid polymer solution is supplied in a manner analogous to that of a dip pen. The minimum applied bias voltage is 600 V, and minimum electrode-to-collector distance is 500 µm to achieve position controllable deposition. Charged nanofibers can be orderly collected, making NFES a potential tool in direct write nanofabrication for a variety of materials.Electrically driven liquid jets and the stability of electrically charged droplets have been studied for hundreds of years, 1,2 while the practical apparatus of electrospinning, in which a charged jet of polymer solution is deposited onto a collector under the influence of an electrical field, dated back in 1934. 3 The feasibility to construct long and continuous polymeric, 4-6 ceramic, 7 and composite 8 nanofibers as well as nanotubes 9 with diameters less than 100 nm has been demonstrated using electrospinning. Typical applications include bioscaffolding, 10 wound dressing, 11 and filtrations 12 to name a few. Researchers have further explored the possibilities of using electrospun nanofibers in fabricating micro-and nanodevices such as field effect transistors, 13 gas 14 and optical sensors, 15 and deposition of DNA on functional chips. 16 In these and other applications, the controllability of the electrospinning process is critical. Unfortunately, current setup of electrospinning is unstable in nature as it relies on the chaotic whipping of liquid jets to generate nanofibers. Limited works toward the control of electrospinning have emerged, including aligning nanofibers by electrical field 17 and using rotational mechanical mandrels. 18,19 Furthermore, numerous investigations by means of analytical and experimental methodologies have been conducted to study the fundamental physics and chemistry of electrospinning for further improvement and control, such as the effects of polymer solution concentration, applied voltage, and electrode-to-collector distance. 4,[20][21][22] Here we report experiments of controllable electrospinning based on a new type of "near-field" electrospinning (NFES). Figure 1A illustrates the schematic setup of NFES that merges several disparate concepts. First, the electrode-to-collector distance, h, is in the range of 500 µm to 3 mm to utilize the stable liquid jets region for controllable deposition. Second, a solid tungsten spinneret of 25 µm tip diameter as illustrated in Figure 1B is used in NFES to achieve nanofibers with sub-100-nm resolution. Third, the applied electrostatic voltage is reduced due to the short electrode-to-collector distance while the electrical field in the tip region maintains the strength in the range of 10 7 V/m as those used in conventional electrospinning to activate the process. Fourth, discrete droplets of polymer solu...

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“…An extensive review of the work on straight axisymmetric liquid jets is given by Eggers 11 and Vanden-Broeck. 12 Curved liquid jets and sheets have been studied before by Weber 13 20 , Yarin et al 21 Hohman et al 22 and others. Here we extend these works and Wallwork et al 2 to develop a long wavelength nonlinear theory for slender inviscid jets subjected to rotational forces.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear travelling waves on a spiralling liquid jet

et al. 2006

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We describe the nonlinear evolution of a travelling wave disturbance on a spiralling slender inviscid jet which emerges from a rotating orifice neglecting gravity. One-dimensional equations are derived using asymptotic methods and solved numerically. Some results are presented for this nonlinear theory which is rather different from previous linear theories, showing the influence of surface tension and rotation on the breakup of the jets into droplets. Comparison with the experimental results shows good qualitative agreement.

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Bending instability of electrically charged liquid jets of polymer solutions in electrospinning

Cited by 2,226 publications

References 21 publications

Crystalline Morphology and Polymorphic Phase Transitions in Electrospun Nylon-6 Nanofibers

Crystalline Morphology and Polymorphic Phase Transitions in Electrospun Nylon-6 Nanofibers

Near-Field Electrospinning

Nonlinear travelling waves on a spiralling liquid jet

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