Electrospinning systems for mass production of nanofibers

Abstract

The present disclosure describes electrospinning systems and apparatuses that are suitable for use in high throughput industrial settings. The disclosed systems and apparatuses may include a high voltage power supply having positive and negative electrodes; one or more spinnerets that include one or more convergent-divergent nozzles, one or more turbo canals, or a combination thereof; and a collector. The systems and apparatuses may further include one or more peristaltic pumps. The collector may be an adjustable collector. The adjustable collector may be composed of multiple metal sheets. The systems and apparatuses may optionally further include one or more of a ventilation system that reduces sparking inside the electrospinning chamber, a chamber for reducing power consumption when using an optional heater or dehumidifier, and an in-line quality control system.

Description

ELECTROSPINNING SYSTEMS FOR MASSPRODUCTION OF NANOFIBERSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 370,643, filed on August 5, 2022, the disclosure of which is hereby incorporated in its entirety herein by reference.BACKGROUNDField of the Invention

[0002] The present disclosure relates to electrospinning systems and apparatuses.Description of the Related Art

[0003] Electrospinning is the most commonly used method for producing nanofibers. The electrospinning process has been extensively studied on account of its potential applications in multiple industries. A wealth of scientific publications explore this area and there are many reasons to believe that nanofibers are a key solution for many applications, including textiles and clothing, military applications, tissue engineering, drug delivery, cancer diagnosis, batteries, optical sensors, and air filtration. Nonetheless, the adoption of electrospinning techniques in industry settings has been extremely slow and limited. This is primarily because electrospinning is perceived as a laboratory scale technique that is difficult to scale up, and thus it is often assumed that electrospinning cannot meet the high throughput demands of industrial applications. Production rates using typical electrospinning technology are usually around 0.01-1 g / h, which is lower than most industry production requirements.

[0004] The instrumentation necessary for electrospinning include a high voltage power supply, a spinneret, and a collector. The spinneret may be a capillary tube with a pipette or needle having a small diameter. The collector may be a metal collecting plate. One electrode of the high voltage power supply is placed into a polymer solution and the other electrode is attached to the collector. An electric field is applied to the end of the capillary tube that contains the polymer solution held by its surface tension and forms a charge on the surface of the liquid. As the intensity of theelectric field increases, the hemispherical surface of the fluid at the tip of the capillary tube elongates, forming a conical shape known as a Taylor cone. A critical value is attained upon a further increase in the electric field, where the repulsive electrostatic force overcomes the surface tension and the charged jet of fluid is ejected from the tip of the Taylor cone. The discharged polymer solution jet is unstable and elongates as a result, allowing the jet to become very long and thin. Charged polymer fibers solidify with solvent evaporation. Randomly oriented nanofibers are collected on the collector. Nanofibers can also be collected in a highly aligned fashion using specialized collectors such as a rotating drum, metal frame, or a two-parallel plate system. Parameters such as jet stream movement and polymer concentration must be controlled to produce nanofibers with uniform diameters and morphologies.

[0005] Electrospinning may be used to transform many types of polymers into nanofibers. An electrospun nanofiber network resembles the extracellular matrix (ECM) in important ways. This resemblance is a major advantage of electrospinning, because it allows for mimicking the ECM with respect to fiber diameters, porosity, and mechanical properties. Electrospinning is being further developed for the mass production of one-by-one continuous nanofibers.

[0006] Current electrospinning technologies typically use a syringe pump to feed the polymer solution into the spinneret. Syringe pumps typically have limited flow rates and limited loading capacities, which necessitate stopping the electrospinning process to refill the syringes.

[0007] Current electrospinning technologies typically use a needle as the spinneret, limiting production capacity.

[0008] Roll-to-roll electrospinning technologies typically entail the deposition of electrospun fibers onto a fabric substrate that unwinds from a first roll to a second roll. The substrate typically passes in front of a metal sheet that is grounded or negatively charged during the spinning process, which may result in “over tension” of the substrate as it passes through the apparatus on account of electrical charges accumulated over the substrate that cause high friction between the substrate and the metal sheet collector. This in turn results in stretching of the fabric substrate. Such stretching may unfavorably alter the tension control of the winders and may also subsequently damage the deposited nanofibers as the substrate relaxes.

[0009] There remains a need for electrospinning systems and apparatuses that overcome the above-described challenges and allow production of nanofibers at high rates.SUMMARY

[0010] The present disclosure describes electrospinning systems and apparatuses that are suitable for use in high throughput industrial settings. The disclosed systems and apparatuses may include a high voltage power supply having positive and negative electrodes; one or more spinnerets that include one or more convergent-divergent nozzles, one or more turbo canals, or a combination thereof; and a collector. The systems and apparatuses may further include one or more peristaltic pumps. The collector may be an adjustable collector. The adjustable collector may be composed of multiple metal sheets. The systems and apparatuses may optionally further include one or more of a ventilation system that reduces sparking inside the electrospinning chamber, a chamber for reducing power consumption when using an optional heater or dehumidifier, and an in-line quality control system.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 shows an embodiment of the disclosed apparatus.

[0012] FIG. 2 shows an embodiment of a peristaltic pump and a schematic representation of a method of phase compensation using multiple peristaltic pumps.

[0013] FIG. 3A shows a schematic representation of the configuration of a convergent- divergent nozzle.

[0014] FIG. 3B shows an example of a convergent-divergent nozzle.

[0015] FIG. 4A shows an example of a turbo canal.

[0016] FIG. 4B shows an example of a polymer solution being fed into a turbo canal.

[0017] FIG. 5 shows an example of a metal collector composed of four metal sheets.

[0018] FIG. 6 shows an example of an in-line quality control system.DETAILED DESCRIPTION

[0019] The present disclosure describes electrospinning systems and apparatuses that are suitable for use in high throughput industrial settings. The disclosed systems and apparatuses may include a high voltage power supply having positive and negative electrodes; one or more spinnerets that include one or more convergent-divergent nozzles, one or more turbo canals, or a combination thereof; and a collector. The systems and apparatuses may further include one or more peristaltic pumps. The collector may be an adjustable collector. The adjustable collectormay be composed of multiple metal sheets. The systems and apparatuses may optionally further include one or more of a ventilation system that reduces sparking inside the electrospinning chamber, a chamber for reducing power consumption when using an optional heater or dehumidifier, and an in-line quality control system.

[0020] FIG. 1 shows an embodiment of the disclosed electrospinning apparatus, including unwinder 1, winder 2, lamination sandwich 3, quality control module 4, feeder 5, turbo canal 6, and collector plates 7.

[0021] The disclosed electrospinning apparatuses use peristaltic pumps to feed the spinneret. This eliminates the need to use syringes. A peristaltic pump can draw a solution from any sized container, which eliminates the need for refilling the polymer solution during the spinning process.

[0022] To prevent interruptions and instability of the spinning jet caused by non-continuous feeding of a single peristaltic pump that results from peristaltic movement, multiple peristaltic pumps are used in the disclosed apparatuses. FIG. 2 shows an example of how two peristaltic pumps having a difference in phase may be used with two separate roll sets to provide overall continuous feeding of the polymer solution. As shown, when phase B is idle, phase A is feeding, and vice versa.

[0023] The disclosed electrospinning apparatuses provide alternate non-needle spinnerets that may be used interchangeably, thereby increasing productivity. The use of these alternate spinnerets may also prevent early solidification of the electrospun polymer as frequently results when a needle is used as the spinneret.

[0024] The alternate spinneret may be a convergent-divergent nozzle, a turbo canal, or another suitable alternate spinneret.

[0025] FIG. 3A shows a schematic representation of the configuration of a convergent- divergent nozzle. FIG. 3B shows an example of a convergent-divergent nozzle. The convergent- divergent nozzle is shaped to promote a polymer solution therein to adopt a cone shape. The use of multiple convergent-divergent nozzles in a rod system, where multiple rods are present in a single apparatus, results in the production of many spinning jets, with multiple jets emerging from a single nozzle.

[0026] FIG. 4A shows an example of a turbo canal. FIG. 4B shows how a peristaltic pump feeds the U-shaped turbo canal with a polymer solution. Use of a turbo canal may provide one or more advantages over the use of other types of spinnerets, including very high productivity,generation of continuous jets, production of homogeneous material, reduced problems with clogging as may occur with needles or nozzles, and simplicity of setup and cleaning.

[0027] The disclosed apparatuses may have one or multiple spinnerets, which may include one or more convergent-divergent nozzles, one or more turbo canals, or a combination thereof. Alternatively, the disclosed apparatuses may have multiple spinnerets that include both needle spinnerets and one or more convergent-divergent nozzles, one or more turbo canals, or a combination thereof.

[0028] The disclosed apparatuses have a reduced contact area between the spinneret and the collector as compared to prior art roll-to-roll electrospinning apparatuses. This is achieved by using multiple metal sheets to form an adjustable collector that allows adjustment and optimization of the gap between the substrate and the collector. By using multiple metal sheets as a collector, the tension on the roll is decreased. The collector may preferably be connected to a negative high voltage electrode to increase the attractiveness of charged fibers.

[0029] In some implementations, the adjustable collector adds one layer of the substrate to laminate the surface of the nanofiber layer, thereby protecting it. Nanofiber layers are thus sandwiched between substrate layers. This eliminates the need to laminate a protective layer as a post-process step for many industrial applications.

[0030] FIG. 5 shows an example of a metal collector composed of four metal sheets.

[0031] Other features of the disclosed apparatuses include a ventilation system that reduces sparking inside the electrospinning chamber, a chamber for reducing power consumption when using an optional heater or dehumidifier, a compact size that is suitable for both research and industrial use, and an in-line quality control system that includes a scanner for measuring the differential pressure between the two surfaces of the substrate to determine the level of homogeneity of fibers produced.

[0032] FIG. 6 shows an example of an in-line quality control system of the disclosed electrospinning system.

[0033] FIG. 7 shows an example of a ventilation system of the disclosed electrospinning system.EXAMPLES

[0034] The following numbered examples further illustrate implementations of the disclosed systems.

[0035] (1) An electrospinning system that includes a high voltage power supply that includes a positive electrode and a negative electrode, one or more spinnerets, and an adjustable collector, where the one or more spinnerets include at least one spinneret that is a convergent-divergent nozzle or a turbo canal, is disclosed.

[0036] (2) The system of (1), wherein the adjustable collector is composed of multiple metal sheets is disclosed.

[0037] (3) The system of (1) or (2), where the system includes at least two spinnerets and at least one spinneret is a convergent-divergent nozzle and at least one spinneret is a turbo canal, is disclosed

[0038] (4) The system of (1) or (2), where the system includes at least two spinnerets and at least one spinneret is a convergent-divergent nozzle or a turbo canal, is disclosed.

[0039] (5) The system of any of (1 )-(4) further including at least one peristaltic pump which feeds a polymer solution into one or more spinnerets is disclosed.

[0040] (6) The system of any of ( 1 )-(4) further including at least two peristaltic pumps which each feed a polymer solution into one or more spinnerets, where at least two peristaltic pumps have a difference in phase that allows continuous feeding of a polymer solution, is disclosed.

[0041] (7) The system of any of (1 )-(6) further including a ventilation system is disclosed.

[0042] (8) The system of any of (l)-(7) further including a chamber for reducing power consumption is disclosed.

[0043] (9) The system of any of (1 )-(8) further including an in-line quality control system is disclosed.

[0044] (10) The system of (9), where the in-line quality control system includes a scanner for measuring a differential pressure between the two surfaces of a substrate to determine a level of homogeneity of nanofibers produced is disclosed.

[0045] (11) An electrospinning system that includes a high voltage power supply that includes a positive electrode and a negative electrode, one or more spinnerets, and a collector, where the one or more spinnerets include at least one spinneret that is a convergent-divergent nozzle or a turbo canal, is disclosed.

[0046] (12) The system of (11 ), where the system includes at least two spinnerets and at least one spinneret is a convergent-divergent nozzle and at least one spinneret is a turbo canal, is disclosed.

[0047] (13) The system of (11), where the system includes at least two spinnerets and at least one spinneret is a convergent-divergent nozzle or a turbo canal, is disclosed.

[0048] (14) The system of any of (11)-(13) further including at least one peristaltic pump which feeds a polymer solution into one or more spinnerets is disclosed.

[0049] (15) The system of any of (11)-(13) further including at least two peristaltic pumps which each feed a polymer solution into one or more spinnerets, where at least two peristaltic pumps have a difference in phase that allows continuous feeding of a polymer solution, is disclosed.

[0050] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention disclosed herein. Although the various inventive aspects are disclosed in the context of certain illustrated embodiments, implementations, and examples, it should be understood by those skilled in the art that the invention extends beyond the specifically disclosed embodiments to other alternative embodiments and / or uses of the invention and obvious modifications and equivalents thereof. In addition, while a number of variations of various inventive aspects have been shown and described in detail, other modifications that are within their scope will be readily apparent to those skilled in the art based upon reviewing this disclosure. It should be also understood that the scope of this disclosure includes the various combinations or sub-combinations of the specific features and aspects of the embodiments disclosed herein, such that the various features, modes of implementation, and aspects of the disclosed subject matter may be combined with or substituted for one another. The generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0051] Each of the foregoing and various aspects, together with those summarized above or otherwise disclosed herein, including the figures, may be combined without limitation to form claims for a device, apparatus, system, method of manufacture, and / or method of use.

[0052] All references cited herein are hereby expressly incorporated by reference.

Claims

CLAIMSWhat is claimed is:

1. An electrospinning system comprising: a. a high voltage power supply that includes a positive electrode and a negative electrode; b. one or more spinnerets; and c. an adjustable collector; wherein the one or more spinnerets include at least one spinneret that is a convergent- divergent nozzle or a turbo canal.

2. The system of Claim 1, wherein the adjustable collector is composed of multiple metal sheets.

3. The system of Claim 1 or 2, wherein the system includes at least two spinnerets and at least one spinneret is a convergent-divergent nozzle and at least one spinneret is a turbo canal.

4. The system of Claim 1 or 2, wherein the system includes at least two spinnerets and at least one spinneret is a convergent-divergent nozzle or a turbo canal.

5. The system of any of Claims 1-4 further comprising at least one peristaltic pump which feeds a polymer solution into one or more spinnerets.

6. The system of any of Claims 1-4 further comprising at least two peristaltic pumps which each feed a polymer solution into one or more spinnerets, wherein at least two peristaltic pumps have a difference in phase that allows continuous feeding of a polymer solution.

7. The system of any of Claims 1-6 further comprising a ventilation system.

8. The system of any of Claims 1-7 further comprising a chamber for reducing power consumption.

9. The system of any of Claims 1-8 further comprising an in-line quality control system.

10. The system of Claim 9, wherein the in-line quality control system includes a scanner for measuring a differential pressure between the two surfaces of a substrate to determine a level of homogeneity of nanofibers produced.

11. An electrospinning system comprising: a. a high voltage power supply that includes a positive electrode and a negative electrode;b. one or more spinnerets; and c. a collector; wherein the one or more spinnerets include at least one spinneret that is a convergent- divergent nozzle or a turbo canal.

12. The system of Claim 11, wherein the system includes at least two spinnerets and at least one spinneret is a convergent-divergent nozzle and at least one spinneret is a turbo canal.

13. The system of Claim 11, wherein the system includes at least two spinnerets and at least one spinneret is a convergent-divergent nozzle or a turbo canal.

14. The system of any of Claims 11-13 further comprising at least one peristaltic pump which feeds a polymer solution into one or more spinnerets.

15. The system of any of Claims 11-13 further comprising at least two peristaltic pumps which each feed a polymer solution into one or more spinnerets, wherein at least two peristaltic pumps have a difference in phase that allows continuous feeding of a polymer solution.

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