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WO2011090995A2 - Structures et procédés de collecte de fibres électrofilées - Google Patents

Structures et procédés de collecte de fibres électrofilées Download PDF

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Publication number
WO2011090995A2
WO2011090995A2 PCT/US2011/021663 US2011021663W WO2011090995A2 WO 2011090995 A2 WO2011090995 A2 WO 2011090995A2 US 2011021663 W US2011021663 W US 2011021663W WO 2011090995 A2 WO2011090995 A2 WO 2011090995A2
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Prior art keywords
fibers
fiber
structures
gap
nanofibers
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PCT/US2011/021663
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WO2011090995A3 (fr
Inventor
Michael John Laudenslager
Wolfgang M. Sigmund
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UNVERSITY OF FLORIDA RESEARCH FOUNDATION Inc
University of Florida Research Foundation Inc
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UNVERSITY OF FLORIDA RESEARCH FOUNDATION Inc
University of Florida Research Foundation Inc
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Publication of WO2011090995A2 publication Critical patent/WO2011090995A2/fr
Publication of WO2011090995A3 publication Critical patent/WO2011090995A3/fr
Anticipated expiration legal-status Critical
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Classifications

    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/0007—Electro-spinning
    • D01D5/0061—Electro-spinning characterised by the electro-spinning apparatus
    • D01D5/0076—Electro-spinning characterised by the electro-spinning apparatus characterised by the collecting device, e.g. drum, wheel, endless belt, plate or grid
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
    • D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
    • D04H1/728—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged by electro-spinning

Definitions

  • nanofibers strongly influences their properties; however, electrospinning, a common nanofiber processing technique, offers limited control over fiber orientation. Therefore, a specific challenge exists to develop methods that are able to control fiber alignment. Electrospinning produces nanofibers from nearly any soluble polymer as well as many ceramic precursors and composite materials. This process produces randomly oriented nanofibers that collect as a nonwoven mesh. While this technique has great versatility in its wide range of synthesizable nanofibers, it is limited by the random orientation of collected fibers. Therefore, techniques for controlling the orientation of the nanofibers are desirable.
  • Embodiments of the present disclosure provide for rotating collection structures, methods of continuously aligning electrospun fibers (e.g., nanofibers), and the like.
  • an embodiment of the method includes orienting the fibers on a collecting plate in a controllable manner and optionally, collecting electrospun fibers continuously.
  • the electrospun fibers can be collected without fracture for the portion of the fiber across the collection plate.
  • the present disclosure includes a method of aligning electrospun fibers, among others, that includes: disposing electrospun fiber(s) on a rotating collection apparatus, wherein the rotating collection apparatus includes a gap between two surfaces, wherein each surface is adapted to attach to a portion of the electrospun fiber, wherein a portion of the electrospun fiber extends across the gap between the two surfaces, wherein each of the two surfaces rotates about an axis; and collecting at least the portion of the electrospun fiber that extends across the gap on a collection plate.
  • the present disclosure includes a rotating collection structure, among others, that includes: two or more parallel structures, wherein between a pair of structures is a gap, wherein each of the structures rotates about an axis; and a collection plate disposed within each gap, wherein the collection plate extends into the gap so that a fiber extending across the gap contacts the collection plate as the structures rotate.
  • FIGS. 1 A and 1 B illustrate a simplified diagram of an embodiment of the present disclosure.
  • FIG. 2A and 2B illustrate a simplified side view of a fiber electrospinning system where the parallel disks and of the rotating collection structure have a different center axis.
  • FIG. 3A to 3C illustrate the alignment of parallel nanofiber arrays.
  • FIG. 3A is a side view of rotary gap device for collecting parallel arrays of fibers on an arbitrary substrate.
  • the conductive strips were connected to a small positive bias (e.g., about 2 kV, but can vary depending on the material used), while the needle was connected to a larger negative bias (-8 kV).
  • FIGS. 3B and 3C are SEM images of aligned electrospun fibers collected for 5 minutes, spun from PVP in ethanol and a T1O2 precursor, respectively.
  • the scale bars are, 100 pm and 10 pm, respectively.
  • the higher conductivity of the ceramic precursor solution slightly lowers the degree of alignment.
  • FIGS. 4A and 4B illustrate the alignment of crossed nanofiber arrays.
  • FIG. 4A illustrates a top view of the device used for collecting crossed arrays of fibers. The dotted line represents the opposite side of the collector.
  • FIG. 4B illustrates an optical micrograph of crossed PVP fiber array. The scale bar is 100 pm. The fibers intersect at an angle of 54°.
  • FIG. 4C illustrates a cross-sectional view of a one of the parallel structures having two semi-circular portions each having a different diameter.
  • FIG. 4D illustrates a cross-sectional view of a one of the parallel structures having three semi-circular portions each having a different diameter.
  • FIG. 5A to 5E illustrates histograms of the alignment of various systems.
  • FIG. 5A to 5C illustrate the angular deviation of fibers spun from a Ti0 2 /PVP precursor solution and collected for 20 s. by: the rotating collection device (FIG. 5A), a stationary gap based device (FIG. 5B), and a high speed rotating mandrel (FIG. 5C).
  • the rotating and stationary gap devices have similar degrees of alignment, while the rotating mandrel device has a much broader distribution.
  • FIG. 5A illustrates the effect of voltage on fiber alignment 15 kV(d) and 7 kV (e). Higher voltage settings appear to decrease the ability of the device to align fibers.
  • FIG. 6A to 6B illustrate SEM images of various methods of fiber alignment.
  • FIG. 6A illustrates a rotary disk method
  • FIG. 6B illustrates a stationary gap based device
  • FIG. 6C illustrates a high speed rotating mandrel.
  • Fiber collection time was 5 minutes in each image. Scale bars 10 microns.
  • Embodiments of the present disclosure will employ, unless otherwise indicated, techniques of chemistry, synthetic organic chemistry, and the like, which are within the skill of the art. Such techniques are explained fully in the literature.
  • Embodiments of the present disclosure provide for rotating collection structures, methods of continuously aligning electrospun fibers (e.g., nanofibers), and the like.
  • An advantage of an embodiment of the present disclosure is that fibers can be controllably oriented (e.g., placement of a fiber relative to the other fibers or angular deviation of the fibers (e.g., about a 2% deviation, about a 5% deviation, about a 8% deviation, or about a 10% deviation)) and/or continuously collected (e.g., with few stops or interruptions) without fracturing (e.g., breaking, fraying, splintering, physically deteriorating, etc) the fibers during the electrospinning process.
  • fracturing the portion of the fiber that spans across the collection substrate is not fractured, but the portion of the fiber across the collection substrate is severed at each end from the originally generated fiber.
  • An advantage of an embodiment of the present disclosure is the ability to continuously collect highly oriented fibers without fracturing the fibers as the fibers are electrospun. Another advantage is that an embodiment can be used to collect (e.g., on a collection plate) the fibers without breaking the fibers or twisting the fibers during alignment on the collection plate. Additional details are provided in the Example.
  • the fibers can be nanofibers (e.g., about 1 to 500 nm or about 10 to 100 nm) or microfibers (e.g., greater than nanofibers up to 10s of micrometers or more).
  • the fibers can have a length in the centimeter range or greater (e.g., a meter or more), or in an embodiment the length of the fiber can be a centimeter or less.
  • the fibers can be oriented on a structure (e.g., collecting or collection plate) in a controllable manner (e.g., design of the device) so that the fibers are substantially parallel (e.g., about 0 to 15 degrees off of parallel alignment or about 0 to 5 degrees off of parallel) or parallel one another.
  • two or more sets of fibers can be oriented on a structure (e.g., collecting or collection plate) in a controllable manner at a predetermined (e.g., selected) angle (e.g., about 5 to 175 degrees) to one another.
  • the fibers form a crisscross pattern or "X" type of pattern.
  • three or more sets of fibers can be oriented on a structure (e.g., collecting or collection plate) in a controllable manner to form a mesh type of pattern, where the angles of different sets of fibers can be different as compared to other sets of fibers, while the angles in each instance can be about 0 to 180).
  • Another perspective to measure how each set of fibers cross is to measure the angle of each set of fibers relative to a plane perpendicular the parallel structures, where the angle(s) in each instance can be about 0 to 180 degrees.
  • Still another perspective to measure how each set of fibers cross is to measure the angle of each set of fibers relative to a plane parallel the parallel structures, where the angle(s) in each instance can be about 0 to 180 degrees.
  • the collected fibers in particular nanofibers, can be used in electronics including thermoelectric and piezoelectric devices, energy storage devices, and as scaffolds for cell growth in biology.
  • the collected fibers can be used in reverse osmosis for water purification, gas separation (permeation) of N 2 from 0 2 , osmosis of salt/fresh water for energy harvesting, fuel cell membranes (e.g., SOFC and polymer), separator membranes for batteries, and the like.
  • a rotating collection structure can include two or more substantially parallel structures (e.g., wheel shaped structure, disk shaped structure, spokes extending from a structure, a structure (e.g., wheel or disk shaped) with spokes, elliptical shaped structure, combinations thereof, and the like, where each parallel structure can be the same or different).
  • the substantially parallel structures can be a single structure with extensions that produce substructures (e.g., the disks) that have a gap between a pair of substantially parallel sub-structures or independent structures that form the pair of substantially parallel structures that have a gap between the independent structures. A gap is present between each pair of substantially parallel structures (or sub-structure as is appropriate for the design of the parallel structures).
  • Each of the structures rotates about an axis (e.g., the same (FIG. 1 A, 1 B, and 3A to 3C) or different axis (FIG. 2A, 2B, and FIG. 4)).
  • the substantially parallel structures can be parallel one another or can be slightly off parallel by up to about 1 degree, up to about 5 degrees, up to about 10 degrees, or up to about 15 degrees, relative to each other. Reference to “parallel structures” herein is done for reasons of clarity but it may also be allowable for "parallel structures” to be replaced with “substantially parallel structures”.
  • a collection plate can be disposed within the gap (or each gap).
  • the collection plate extends into the gap so that a fiber (e.g., nanofiber) extending across the gap contacts the collection plate as the parallel structures rotate and is collected on the collection plate.
  • the parallel structures can rotate at various speeds depending on the fiber material, the fiber diameter, the fiber material flow rate, the strength of the collection plate, and the like.
  • the collection plate can have a width so that it can be disposed within the gap.
  • the collection plate can be about 99%, 95%, 90%, 80%, 70%, 50% or so, of the width across the gap.
  • the collection plate can have a square shape, rectangular shape, a polygonal shape, circular shape, semi-circular shape, an elliptical shape, and irregular shape, and combinations thereof.
  • the collection plate can collect only the portion of the fiber disposed across the gap. In other words, the collection plate cuts the fiber so only the portion across the gap is collected. In an embodiment, the collection plate can collect the fiber so that more than just the portion across the gap is collected. In other words, a longer portion of the fiber (e.g., 110% of the width of the collection plate) can be collected.
  • the collection plate can be made of a material strong enough to withstand the collection of the fibers. In an embodiment, the collection plate is made of glass, but it can be envisioned that many other types of materials (e.g., metal, ceramic, paper, and the like) could be used depending on the use of the fibers, type of fibers, and the like.
  • the parallel structures can include two parallel structures, while in other embodiments the number of parallel structures can be three (e.g., two gaps), four (e.g., three gaps), five (e.g., four gaps), or (e.g., five gaps) six or more.
  • each of the parallel structures can have the same axis of rotation (FIG. 1A, 1 B, and 3A to 3C) or each can have different axis of rotation (FIG. 2A, 2B, and FIG. 4) or some with the same axis and others with a different axis of rotation.
  • the parallel structures can have an arcuate cross-section, a circular cross-section, a polygonal cross-section, an elliptical cross section, two or more semi-circular cross-sections on a single structure each with a different radius (See FIG. 4C and 4D), and a combination thereof, with or without spokes.
  • the diameter (or length across the structure) of the parallel structures can be about 2 to 10 cm, about 2 to 6 cm, or about 4 cm or more, and can be on the order of a meter (e.g., about 0.5 m to 2 m) or meters (e.g., about 2 to 10 m or about 2 to 5 m).
  • a meter e.g., about 0.5 m to 2 m
  • meters e.g., about 2 to 10 m or about 2 to 5 m.
  • the width of each parallel structure (not including spokes) is about 0.1 to 2 cm or about 0.5 to 1.5 cm.
  • each of the parallel structures includes an electrically conductive portion or a plurality of electrically conductive portions to which a potential can be applied so that the fiber attaches to the electrically conductive portion of one of the parallel structures and then spans across to the other parallel structure and so on.
  • the type and position of the electrically conductive portion can vary among the various configurations as long as the electrically conductive portions can be used to attach to the fibers.
  • the electrically conductive portion can be an electrically conductive metal (e.g., copper) or metal alloy, electrically conductive ceramic, an electrically conductive polymer, of the like.
  • each parallel structure is a disk having a circular cross- section.
  • the disks include an electrically conductive portion on the outside edges of the disks so that the fiber attaches to the electrically conductive portion.
  • the electrically conductive portion is only on select portions of the outside edges of the disks.
  • the structures are spokes extending from a structure.
  • the ends of each spoke or a portion of the spoke are electrically conductive so it is adapted to attach to a portion of the fiber.
  • the number of spokes can vary from 10s to 1000s or more depending on the diameter of the structure and the like.
  • the length of the spokes can be long or short.
  • the long spokes can be about 2 to 10 cm, about 2 to 6 cm, or about 4 cm or more and can be on the order of a meter (e.g., about 0.5 m to 2 m) or meters (e.g., about 2 to 10 m or about 2 to 5 m).
  • the short spokes can be about 1 to 50 mm or about 1 to 20 mm.
  • the diameter or width of the spokes can be from less than a millimeter to a few centimeters or more.
  • the spokes can be tapered is diameter along the length of the spoke.
  • the gap (or each gap if more than one is included) can be about 1 cm to 5 cm across or about 2 to 3 cm across, or the gap can be on the order of 10s of cm.
  • an electrospinning fiber system can include a device (e.g., syringe) that is positioned adjacent the parallel structures so that fibers can be drawn out of the syringe (as known in the art) or other device and onto the substantially parallel structures and across the gap based on the potential difference.
  • a device e.g., syringe
  • two or more devices can feed fiber to the parallel structures at different positions around the parallel structures, which can increase throughput, for example.
  • the material of the fiber can be made of one or more polymers (e.g., polyolefin, polyamides, polyesters, polyurethanes, polypeptides, polysaccharides, and the like), sol gels, suspensions, melts, ceramic materials, metallic materials, and combinations thereof.
  • An electric field (e.g., about 1 kV/cm to 3kV/cm) is produced between the device and the parallel structures and between the parallel structures using appropriate electronic systems.
  • the potential difference between the device and the electrically conductive portion of the parallel structure is about 5 kV to 60 kV or about 10 kV, while the distance between the device and the electrically conductive portion of the parallel structure is about 5 cm to 20 cm.
  • the potential difference can vary depending on the various distances and dimensions as well as material used to make the fiber.
  • FIG. 1 A and 1 B illustrate a simplified diagram of an embodiment of the present disclosure.
  • FIG. 1 A illustrates the electrospinning fiber system 10 from the top and
  • FIG. 1 B illustrates the electrospinning fiber system 10 from the side.
  • the electrospinning fiber system 10 includes a device 12 for feeding a liquid jet that forms a fiber 14 as the liquid dries, to the rotating collection structure 16.
  • the fiber collects on the parallel disks 18 and 22 of the rotating collection structure 16 so that the fiber spans the gap 24 between the parallel disks 18 and 22.
  • a collection plate 26 can be disposed in the gap 24 to collect the fiber (not shown).
  • FIG. 2A and 2B illustrate a simplified side view of an electrospinning fiber system 30 where the parallel disks 34 and 36 of the rotating collection structure 32 have a different center axis 38 and 32.
  • the different center of axis causes the parallel disks 34 and 36 to alternative forward and backward resulting in the fibers crossing one another at angles as described herein. Additional details are provided in the Example.
  • the method includes collecting electrospun nanofibers continuously.
  • the method is conducted using the rotating collection structures described herein and in the Example.
  • the method includes orienting the nanofibers on a collecting plate in a controllable manner (e.g., selection of the parallel structure dimensions, design, potential difference, and the like).
  • the orienting includes orienting the nanofibers so the nanofibers are substantially parallel one another or parallel one another. See the Example and FIGS. 3A to 3C for additional discussion.
  • the orienting includes orienting a first set of individual fibers (e.g., nanofibers) at a first angle across the collection plate (e.g., relative to a plane perpendicular the parallel structures) and also includes orienting a second set of individual nanofibers at a second angle across the collection plate (e.g., relative to a plane perpendicular the parallel structures) so that the first set and the second set are not parallel to one another (e.g., the first set of individual nanofibers and the second set of individual nanofibers cross one another (e.g., forming an "X" type of pattern)).
  • a first set of individual fibers e.g., nanofibers
  • the first angle is a selected predetermined angle (e.g., about 5 to 170 degrees) and the second angle is a selected predetermined angle (e.g., about 5 to 170 degrees).
  • the predetermined angles can be selected by adjusting one or more variables such as the disk diameters in relation to each other, other dimensions of the disk, potential differences, and the like.
  • substantially all (e.g., greater than about 60%, about 70%, about 80%, about 90%, about 95%, or more) of the nanofibers are included in the first set and the second set.
  • three or more sets of fibers can be oriented relative to one another. This could be accomplished by having three or more "wedges” or “grooves” formed by the rotating apparatus (See FIG. 4A that shows two wedges), which are formed by differences in radii of portions of each parallel structure. As each portion of the parallel structure that differ in radius come close to one another during rotation thereof, a "wedge” or “groove” can be observed by looking at the parallel structures from the side (See FIG. 4A).
  • the wedge or groove can be designed by tapering the intersection between the area where the two portions of different radii meet, tapering can be used to reduce the likelihood of the fiber snagging on areas that the fiber is not intended to attach to.
  • each parallel structure includes two (or more) semi-circle portions, each having a different radius.
  • Each parallel structure is offset by about 180 degrees of rotation from the other if the each parallel structure includes two semi-circular portions, and offset by a smaller amount when three or more semicircular portions are used in the design.
  • the semi-circle portions can be replaced with other designs (e.g., cross-sections) including spokes of different lengths on different portions of the parallel structures.
  • FIG. 4C illustrates a cross-sectional view of one of the parallel structures having two semi-circular portions (A and B) each having a different radius. Another identical parallel structure can be used in conjunction with this one to form a pair of parallel structures, where the two parallel structures are out phase with one another by about 180 degrees.
  • FIG. 4D illustrates a cross-sectional view of one of the parallel structures having three semi-circular portions (A, B, and C) each having a different radius.
  • Another identical parallel structure can be used in conjunction with this one to form a pair of parallel structures, where the two parallel structures are out phase with one another by an appropriate amount to form the desired pattern on the collection plate. Additional parallel structures can be added in a similar fashion.
  • the first and second angles can be created when the parallel structures have different axis of rotation as shown in FIGS. 2A and 2B and FIG. 4 and the Example or the have the same axis of rotation but have two or more semi-circular portions each having different diameters as shown in FIG. 4.
  • the method includes continuously aligning electrospun fibers (e.g., nanofibers).
  • the method includes disposing electrospun fiber(s) on a rotating collection apparatus as described herein.
  • the rotating collection apparatus includes a gap between two surfaces. Each surface is adapted to attach to (e.g. , electrically interact with) a portion of the electrospun nanofiber.
  • the fiber can attach to a spoke. A portion of the electrospun nanofiber extends across the gap between the two surfaces. Each of the two surfaces rotate about an axis (same or different) as described herein.
  • the collecting step can include collecting the electrospun nanofibers without fracture for the fiber across the collection substrate.
  • the method includes collecting at least the portion of the electrospun nanofiber that extends across the gap on a collection plate.
  • the nanofibers collected on the collection plate may be substantially parallel or parallel one another.
  • two or more sets of nanofibers can be positioned relative to one another at angles (e.g. , so the sets crisscross) described herein and described in the Examples.
  • the collection plate extends into a space of the gap so that a portion of the electrospun nanofiber that extends across the gap contacts the collection plate as the two surfaces rotate. In an embodiment, less than the portion of the nanofiber that extends across the gap is disposed on the collection plate. In an embodiment, the portion of the nanofiber that extends across the gap is disposed on the collection plate. In an embodiment a larger portion of the nanofiber is disposed on the collection plate.
  • collecting can include collecting the nanofiber or microfiber for long periods of time and/or large quantities of nanofibers (e.g. , milligrams to grams) since the material to form the fiber can be continually fed to the device. In an embodiment, collecting includes collecting about 1 to 100 milligrams of nanofiber or microfiber per hour from a single syringe that include about 1 to 50 grams of fiber material.
  • a plurality of these systems can be run in parallel to collect large quantities of fiber.
  • multiple syringes and multiple gaps can be used to collect the fiber.
  • the method also includes orienting the nanofibers on a collecting plate as described herein.
  • Electrospinning produces nanofibers from electrically charged jets in a process outlined as follows: first, a syringe is filled with a polymer or a ceramic precursor solution, and an advancement pump is used to generate a droplet of the solution at the needle tip. By applying a potential difference between the needle and a target, the droplet deforms into a Taylor cone. From the elongated droplet, a liquid jet emerges and accelerates toward a target with lower electrostatic potential.
  • FIG. 3A shows the device for collecting parallel arrays of fibers.
  • V-shaped wedges are necessary to prevent fibers from collecting at errant angles. Without this gap, fibers orient along a third, undesirable location.
  • fibers are collected on aluminum foil, which fibers strongly adhere to. This method provides another advantage; the collection substrate need not be a highly conductive material. This greatly eases the transfer of fibers to other surfaces.
  • the stationary gap method aligns fibers across two parallel substrates with a small space between them. A significant portion of fibers collect across the gap and form parallel or perpendicular arrays 15 . This method, however, is only useful for thin meshes. After the initial layer of fibers span the gap, additional fibers become increasingly less oriented with time due to interactions with previously deposited ones. Other methods that manipulate the electric or magnetic field have similar limitations 4,16"20 . Alternately, the high-speed rotating mandrel technique collects large quantities of aligned fibers. In this technique the alignment ability is related to the rotational speed 21"22 . Faster rotation result in better fiber alignment; however, the high speed needed results in many broken fibers.
  • FIGS. 5A, 5B, and 5C show the angular deviation of the three techniques using the ceramic precursor.
  • the proposed alignment technique and the stationary gap collector have similar distributions. 80% of the stationary gap fibers and 83% of the rotating gap fibers have a deviation within ⁇ 10 degrees. The angular deviation of fibers recorded in FIGS. 5C shows that the rotating mandrel only collected 34% of fibers within ⁇ 10 degrees, which is substantially less than the other techniques.
  • the high rotational speed of the device breaks the fibers in many locations.
  • One cause of the greater number of outliers in the rotary gap method is that fibers have insufficient time to fully span the gap; however, the rotational speed used in this experiment was the slowest possible setting available.
  • FIG. 6 demonstrates aligned arrays of fibers spun from polyvinylpyrrolidone (PVP) for five minutes using the three techniques. Fibers collected across a stationary gap for this length of time exhibit a significantly higher number of irregularities. These fibers are noticeably more wavy and less densely packed than when the fibers were collected for shorter periods of time (FIG. 6b). With the continuous gap collection device, layered nanofibers retain their alignment even after large quantities of fibers are collected (FIG. 6a). The rotating mandrel has a much lower degree of alignment than the other techniques. Several broken fibers are also easily observed in the image.
  • PVP polyvinylpyrrolidone
  • FIGS. 5d and 5e shows that nanomeshes collected at 1.5 kV have greater deviation in their alignment angles than those collected at 7 kV. In both cases the distance from the needle tip to the collector was 10 cm. Highly charged and highly conducting fibers tend to attach to the collector at one end and stand out perpendicularly until charges dissipate, requiring more time to collect across the gap. Thus, a slower rotation speed could allow better alignment at higher voltages or with highly conducting fibers.
  • gap width produced no significant differences in fiber angle orientation, but collection efficiency decreased as gap width increased.
  • 1.5 cm gap width up to 34 wt. % of electrospun material collects on the final substrate.
  • the gap width was adjusted from 1.5 cm to 3 cm with no effect on fiber alignment.
  • the maximum gap PVP fibers would span was 6 cm; however, as the width was increased, an increasingly smaller portion of the fibers collected across the gap. Beyond this spacing, fibers only collected on one side of the collector.
  • fibers will preferentially collect only on one part of the collect and not span the gap.
  • flow rate impacts fiber alignment. Lower flow rates, favoring thinner fiber formation, result in higher degrees of alignment. Higher flow rates enable the electric field to pull larger amounts of liquid in multiple directions resulting in branched structures. Such structures appear to have greater spacing between fibers and greater variation in fiber diameters, which could prove interesting for directed cell growth applications.
  • a final observed effect is a slight outward curvature of the fibers from the collector. This behavior has two possible causes: fibers stretch under their own weight or incomplete dissipation of charge causes the fibers to arch outward.
  • Nanoscale crossbar arrays can also be used as decoders for integrated systems and biological sensor arrays 24"28 .
  • the parallel alignment device was constructed by connecting two plastic discs with a rod through their center.
  • the disks were typically spaced with a gap of 1.5 cm.
  • the edges of each disc were covered in a thin strip of copper to attract the electrospun fibers.
  • a third strip of copper electrically connected the two halves of the collector through the middle of the device.
  • Several materials were used for the collection substrate including Teflon, glass, and carbon tape.
  • a small positively biased voltage (+2 kV) was connected to the copper strip. Adding an oppositely biased potential greatly improves the quantity of fibers that collect in the desired area.
  • the entire apparatus was rotated at the slowest speed possible (Caframo BDC 3030 variable- speed stirrer) with the available equipment (7.5 cm/s at the edge of the discs).
  • the needle was typically positioned 10 cm from the collection apparatus and a negative bias was applied (-8 kV).
  • the syringe was placed in an advancement pump set to 0.5 mL/h.
  • the electrospun solutions in this experiment consisted of poly (vinylpyrrolidone), molecular weight 1 ,300,000 (Acros Organic), in ethanol (1 g/mL), and a Ti02/PVP ceramic precursor (0.6 g PVP, 2 mL acetyl acetone(Fisher Chem.), 9 mL ethanol, and 0.6 g titanium butoxide (Acros Organic).
  • SEM images were taken with a JEOL 6335F FEG-SEM, and optical images were taken with an Olympus BX60 with a SPOT Insight digital camera. ImageJ software was used to measure fiber orientation and diameter.
  • Angular deviations of the fibers were determined as follows: the angles between the fibers and a horizontal line were measured. Since the fibers were aligned in an arbitrary direction in the SEM image, the data is reported such that the mean of each data set is at zero degrees. At least one hundred fibers were measured for each distribution. While the majority of fibers were straight and oriented, a small number of fibers were observed to have a random, circular orientation. It is difficult to describe these fibers as having a specific angular deviation since that value changes arbitrarily depending where along the fiber it measures. Therefore, outliers in the histograms do not necessarily have any specific orientation.
  • Electrospun nanofibers solving global issues.
  • Nanofibers as Uniaxially Aligned Arrays Nano Letters 3, 1 167-1 71 (2003). Teo, W., Kotaki, M., Mo, X. & Ramakrishna, S. Porous tubular structures with controlled fibre orientation using a modified electrospinning method.
  • ratios, concentrations, amounts, and other numerical data may be expressed herein in a range format. It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or subranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
  • a concentration range of "about 0.1 % to about 5%” should be interpreted to include not only the explicitly recited concentration of about 0.1 wt% to about 5 wt%, but also include individual concentrations (e.g., 1 %, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.5%, 1 .1 %, 2.2%, 3.3%, and 4.4%) within the indicated range.
  • the term "about” can include traditional rounding according to significant figures of the numerical value.
  • the phrase "about 'x' to 'y'" includes “about 'x' to about 'y'".

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
  • Nonwoven Fabrics (AREA)

Abstract

Des modes de réalisation de la présente invention concernent des structures de collecte rotatives, des procédés d'alignement de fibres électrofilées (par exemple, de nanofibres) et similaires.
PCT/US2011/021663 2010-01-19 2011-01-19 Structures et procédés de collecte de fibres électrofilées Ceased WO2011090995A2 (fr)

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CN103981579A (zh) * 2014-05-04 2014-08-13 清华大学深圳研究生院 静电纺丝收集装置、方法以及静电纺丝设备
CN104818536A (zh) * 2015-04-03 2015-08-05 西安交通大学 一种定向排列的静电纺丝纤维制备装置和制备方法
CN104894660A (zh) * 2015-06-29 2015-09-09 苏州大学 一种动态平行滚筒电极静电纺丝设备及方法
WO2016184439A1 (fr) * 2015-05-15 2016-11-24 České vysoké učení technické v Praze Appareil de production de nanofibres ou de microfibres
CN108034994A (zh) * 2017-12-21 2018-05-15 西安工程大学 一种制备椎间盘纤维环的静电纺丝装置及其方法
EP3956077A4 (fr) * 2018-08-01 2023-01-18 Ultra Small Fibers, LLC Procédé de modification de la mouillabilité de surfaces

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103981579A (zh) * 2014-05-04 2014-08-13 清华大学深圳研究生院 静电纺丝收集装置、方法以及静电纺丝设备
CN104818536A (zh) * 2015-04-03 2015-08-05 西安交通大学 一种定向排列的静电纺丝纤维制备装置和制备方法
WO2016184439A1 (fr) * 2015-05-15 2016-11-24 České vysoké učení technické v Praze Appareil de production de nanofibres ou de microfibres
CN104894660A (zh) * 2015-06-29 2015-09-09 苏州大学 一种动态平行滚筒电极静电纺丝设备及方法
CN108034994A (zh) * 2017-12-21 2018-05-15 西安工程大学 一种制备椎间盘纤维环的静电纺丝装置及其方法
EP3956077A4 (fr) * 2018-08-01 2023-01-18 Ultra Small Fibers, LLC Procédé de modification de la mouillabilité de surfaces

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