The present specification generally relates to electrospinnable fibers and, more specifically, to hydrophobic coaxial fibers produced by coaxial electrospinning.
Superhydrophobic materials and surfaces that produce water contact angles in excess of 150° are being intensively studied in order to provide superior water repellency and self-cleaning behavior. This unique property is very useful in many industries, such as microfluidics, textiles, construction, automobiles, and so forth. Many examples of superhydrophobicity are found in nature, especially in plants and insects. For example, lotus leaves are superhydrophobic because of their rough-surface microstructure. Self-cleaning occurs as water droplets remove surface particles as they roll off the leaves. Superhydrophobicity also provides good buoyancy for floating on water. Another example from nature is the lady's mantle leaf that obtains its superhydrophobicity from a furlike coverage of bundled hairs. Interestingly, individual hairs are hydrophilic. However, the elastic deformation of the bundled hair ends away from the substrate results in a superhydrophobic surface. The bundling of the hairs is an example of the importance of curvature in hydrophobicity. This curvature effect is also very important in determining the oil-repellent (“oleophobic”) properties of the surface. Water strider feet and bird feathers are other famous examples of superhydrophobicity present in nature. By observing these features, one realizes that superhydrophobicity results from a combination of low surface energy and high surface roughness.
Several approaches have been reported for combining materials of low surface energy with high surface roughness. One approach is to roughen a normally smooth surface of a hydrophobic material. Plasma etching is widely used for this purpose. Mechanical stretching and microphase separation of fluorinated block copolymers have also been used. A second approach is to treat a rough surface with a hydrophobic material. Etching, lithography, and nanowires/nanotubes by chemical vapor deposition (CVD) have been used to produce a rough surface, followed by a hydrophobic coating to produce a low surface energy. Whereas these approaches are two-step processes, single-step approaches, such as sol-gel phase separation and plasma polymerization, can also produce a rough surface with low surface energy.
Electrospinning is a versatile technique for producing micro-nanofibers from many kinds of polymers. In a laboratory environment, electrospinning requires a high-power supply, a conducting substrate, and a syringe pump. The electro-spinning process is initiated by a high electric field between the syringe containing viscous polymer solution) and the conducting substrate. Because of the high electrical potential, a charged liquid jet is ejected from the tip of a distorted droplet, the so-called Taylor cone. This liquid jet experiences whipping and bending instabilities within a sufficient distance to evaporate its solvent thoroughly and, consequently, becomes a solid nonwoven micro/nanofiber membrane on the substrate. Oriented polymer nanofibers can also be produced by modifying the ground electrode geometry and/or rotating it and by using a microfluidic chip to deliver the solution to the ejection tip.
However, due to their relatively low dielectric constants, many hydrophobic materials are not susceptible to electrospinning. Electrospinning has been used to make membranes with rough surfaces, followed by the deposition of hydrophobic material. For example, rough membranes are electrospun first and then coated with hydrophobic material by deposition techniques such as CVD and the layer-by-layer technique. However, this process can require additional cost and material to sufficiently coat the electrospun membrane.
Accordingly, a need exists for alternative methods for electrospinning hydrophobic coaxial fibers into superhydrophobic coaxial fiber mats.
In one embodiment, a method for electrospinning a hydrophobic coaxial fiber into a superhydrophobic coaxial fiber mat is provided. The method may include providing an electrospinning coaxial nozzle comprising a core outlet coaxial with a sheath outlet, ejecting an electrospinnable core solution from the core outlet of the electrospinning coaxial nozzle, ejecting a hydrophobic sheath solution from the sheath outlet of the electro spinning coaxial nozzle, wherein the hydrophobic sheath solution annularly surrounds the core solution, applying a voltage between the electrospinning coaxial nozzle and a collection plate, wherein the voltage induces a jet of the electrospinnable core solution annularly surrounded by the hydrophobic sheath solution to travel from the electrospinning coaxial nozzle to the collection plate to form the hydrophobic coaxial fiber comprising an electrospinnable polymer core coated with a hydrophobic sheath material, and wherein collection of the hydrophobic coaxial fiber on the collection plate yields the superhydrophobic coaxial fiber mat.
In another embodiment, a superhydrophobic coaxial fiber mat includes an electrospun hydrophobic coaxial fiber, wherein the electrospun hydrophobic coaxial fiber includes an electrospinnable polymer coated with a hydrophobic sheath material, the hydrophobic sheath material comprising 1 weight percent to 10 weight percent of the superhydrophobic coaxial fiber mat, and wherein, the superhydrophobic coaxial fiber mat possesses a contact angle greater than or equal to 150° with water.
These and additional features provided by the embodiments described herein will be more fully understood in view of the following detailed description, in conjunction with the drawings.
The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
As used herein with the various illustrated embodiments described below, the follow terms include, but are not limited to, the following meanings.
The term “electrospinning” can mean applying an electric field between a nozzle containing an electrospinnable polymer and a conducting substrate (such as by applying a voltage between the two) such that a charged liquid jet of the electrospinnable core solution containing the electrospinnable polymer is ejected from the tip of a distorted droplet from the nozzle (i.e., the so-called Taylor cone) and experiences whipping and bending instabilities for a sufficient distance to evaporate its solvent thoroughly and, consequently, become a solid electrospinnable polymer core.
The term “electrospinning coaxial nozzle” can mean a conductive nozzle comprising a core outlet coaxial with a sheath outlet.
The term “electrospinnable core solution” can mean an electrospinnable polymer and a core solvent.
The term “electrospinnable polymer” can mean any polymer sufficient to hold a charge such that an electric field can electrospin the electrospinnable polymer, such as, for example, synthetic polymers (e.g., poly(∈-caprolactone) (PCL), poly(methyl methacrylate) (PMMA), nylon, polyurethane, poly-lactic gycolic acid (PLGA), polyethylene, poly(lactic acid), poly(ethylene oxide), polystyrene, polycarbonate, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyacrylonitrile (PAN), or NOMEX), biomaterials (e.g., DNA-CTMA, cellulose acetate, collagen, gelatin, or chitosan), and the like.
The term “core solvent” can mean any solvent that dissolves the electrospinnable polymer to comprise the electrospinnable core solution, such as, for example an organic solvent (e.g., trifluoroethanol (TFE), hexafluoro-iso-propanol (HFIP), chloroform (CF), tetrahydrofuran (THF), dimethylformamide (DMF), or methylene chloride), an aqueous solvent (e.g., water or formic acid such as for example), and the like.
The term “hydrophobic sheath solution” can mean a hydrophobic material and a sheath solvent.
The term “hydrophobic material” can mean any material that can coat the electrospinnable polymer core and provide hydrophobic and/or oleophobic properties, such as, for example, an amorphous fluoropolymer and the like.
The term “sheath solvent” can mean any solvent that dissolves the hydrophobic material to comprise the hydrophobic sheath solution, such as, for example, perfluoro(butyltetrahydrofuran), perfluorohexane, other fluorinert compounds, perfluoro compounds, and the like.
The term “hydrophobic coaxial fiber” can mean a an electrospinnable polymer core coated with a hydrophobic sheath material.
The term “superhydrophobic coaxial fiber mat” can mean one or more electrospun hydrophobic coaxial fibers gathered together in a random or oriented configuration to provide superhydrophobic properties.
The term “hydrophobic” can mean possessing a contact angle greater than or equal to 90° with water.
The term “superhydrophobic” can mean possessing a contact angle greater than or equal to 150° with water.
The term “oleophobic” can mean possessing an alkane contact angle greater than or equal to 90° with alkanes.
Referring now to
As illustrated in
Referring back to method 90 for electrospinning a hydrophobic coaxial fiber 40 into a superhydrophobic coaxial fiber mat 50, an electrospinnable core solution 12 is ejected from the core outlet 13 of the coaxial nozzle 10 in step 92. The electrospinnable core solution 12 can comprise an electrospinnable polymer and a core solvent. The electrospinnable polymer can comprise any polymer sufficient to hold a charge such that an electric field can electrospin the electrospinnable polymer. Specifically, the polymer must hold a sufficent charge so that the electric field (created by applying a voltage between the electrospinning coaxial nozzle 10 and the collection plate 30) causes the electrospinnable polymer in the ejected electrospinnable core solution 12 to form an electrospinnable polymer core 41 of a electrospun hydrophobic coaxial fiber 40. For example, the electrospinnable polymer can comprise a synthetic polymer (such as, for example, poly(∈-caprolactone) (PCL), poly(methyl methacrylate) (PMMA), nylon, polyurethane, poly-lactic gycolic acid (PLGA), polyethylene, poly(lactic acid), poly(ethylene oxide), polystyrene, polycarbonate, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyacrylonitrile (PAN), or NOMEX), a biomaterial (such as, for example, DNA-CTMA, cellulose acetate, collagen, gelatin, or chitosan) or combinations thereof. While these materials are listed as potential electrospinnable polymers for the electrospinnable core solution 12, this list is exemplary only and other electrospinnable polymers may additionally or alternatively be used.
The core solvent of the electrospinnable core solution 12 can comprise any solvent that dissolves the electrospinnable polymer to comprise the electrospinnable core solution 12. For example, the core solvent can comprise an organic solvent (such as, for example, trifluoroethanol (TFE), hexafluoro-iso-propanol (HFIP), chloroform (CF), tetrahydrofuran (THF), dimethylformamide (DMF), or methylene chloride), an aqueous solvent (such as, for example, water or formic acid), or combinations thereof. In one embodiment, the core solvent may be selected based on the particular electrospinnable polymer or electrospinnable polymers in the electrospinnable core solution 12. For example, where the electrospinnable polymer in the electrospinnable core solution comprises poly(∈-caprolactone) or poly(methyl methacrylate), the core solvent may comprise trifluoroethanol. While these solvents are listed as potential core solvents for the electrospinnable core solution 12, this list is exemplary only and other core solvents may alternatively be used to dissolve the electrospinnable polymer to comprise the electrospinnable core solution 12.
The electrospinnable core solution 12 can comprise any relative weight percents of the electrospinnable polymer and the core solvent to allow for the electrospinning of the electrospinnable core solution 12 into the electrospinnable polymer core 41 of the electrospun hydrophobic coaxial fiber 40 as illustrated in
Furthermore, the electrospinnable core solution 12 ejected from the core outlet 13 of the electrospinning coaxial nozzle 10 in step 92 of method 90 is ejected at a core flow rate. The core flow rate can be a constant flow rate, an incremental flow rate, a variable flow rate or any combination thereof. For example, as illustrated in
Referring still to
The sheath solvent of the electrospinnable core solution 12 can comprise any solvent that dissolves the hydrophobic material (e.g., the fluoropolymer) to comprise the hydrophobic sheath solution 16. For example, in one embodiment, such as where the hydrophobic sheath material comprises an amorphous copolymer of polytetrafluororoethylene and 2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxole, the sheath solvent may comprise perfluoro(butyltetrahydrofuran) (also known as Fluorinert FC-75, or simply FC-75, and commercially available from 3M), perfluorohexane (also known as Fluorinert FC-72, or simply FC-72, and commercially available from 3M), other Fluorinert compounds like FC-40 (commercially available from 3M), perfluoro compounds, or combinations thereof. In another embodiment, such as where the hydrophobic sheath material comprises CYTOP, the sheath solvent may comprise CT-solv 180 (commercially available from Asahi Glass), CT-solv 100 (commercially available from Asahi Glass), or combinations thereof. In yet another embodiment, such as where the hydrophobic material comprises FluoroPel, the sheath solvent may comprise perfluoropolyether (PFPE), perfluoroalkane, halocarbon, hydrofluoroether or combinations thereof. While these solvents are listed as potential sheath solvents for the hydrophobic sheath solution 16, this list is exemplary only and other sheath solvents may alternatively be used to dissolve the hydrophobic material to comprise the hydrophobic sheath solution 16.
The hydrophobic sheath solution 16 can comprise any relative weight percents of the hydrophobic material and the sheath solvent to allow for the hydrophobic sheath material 42 to coat the electrospinnable polymer core 41 of a hydrophobic coaxial fiber 40 from electrospinning as illustrated in
Furthermore, the hydrophobic sheath solution 16 ejected from the sheath outlet 17 of the electrospinning coaxial nozzle 10 in step 93 of method 90 is ejected at a sheath flow rate. Similar to the core flow rate, the sheath flow rate can be a constant flow rate, an incremental flow rate, a variable flow rate or any combination thereof. For example, as illustrated in
Referring now to
As appreciated to those skilled in the art, the miscibility between the electrospinnable core solution 12 and the hydrophobic sheath solution 16 (and more specifically the electrospinnable polymer and the hydrophobic material) may influence the mechanical properties of the electrospun hydrophobic coaxial fiber 40 and the resulting superhydrophobic coaxial fiber mat 50. For example, immiscible solutions provide for little or no interactions between the electrospinnable polymer core 41 and the hydrophobic sheath material 42. Conversely, miscible solutions may still allow for the electrospinning of hydrophobic coaxial fibers 40; however, the electrospinnable polymer core 41 may possess reduced mechanical strength compared to when used with immiscible solutions. In one embodiment, where the hydrophobic sheath material comprises the relatively immiscible material Teflon, the electrospinnable polymer core may significantly retain its mechanical strength.
Referring now to
Furthermore, the voltage may be applied in step 94 between the electrospinnable coaxial nozzle 10 and the collection plate in any sufficient manner to allow for the electrospinning of the electrospun hydrophobic coaxial fiber 40. For example, as in one embodiment, as illustrated in
Similar to the electrospinning coaxial nozzle 10, the collection plate 30 can comprise any conductive material such that a voltage supplied from a power supply 20 can be transferred through the collection plate. For example, the collection plate 30 can comprise any conductive metal, alloy, or other electrically conductive material. Furthermore, the electrospinning coaxial nozzle 10 may be separated from the collection plate 30 by any distance D that allows both the electrospinnable core solution 12 and the hydrophobic sheath solution 16 enough travel time for their respective solvents to evaporate to form the electrospun hydrophobic coaxial fiber 40. For example, in one embodiment, the distance D between the electrospinning coaxial nozzle 10 and the collection plate 30 may comprise less than or equal to 50 centimeters (cm). In another embodiment, the distance D between the electrospinning coaxial nozzle 10 and the collection plate 30 may comprise less than or equal to 30 cm. In yet another embodiment, the distance D between the electrospinning coaxial nozzle 10 and the collection plate 30 may comprise from about 20 cm to about 25 cm.
The resulting electrospun hydrophobic coaxial fiber 40 electrospun from the hydrophobic coaxial fiber electrospinning system 100 thereby comprises an electrospinnable polymer core 41 (derived from the electrospinnable core solution 12) coated with a hydrophobic sheath material 42 (derived from the hydrophobic sheath solution 16) as illustrated in
Referring still to
The superhydrophobic coaxial fiber mat 50 formed from method 90 (such as by using the hydrophobic coaxial fiber electrospinning system 100 as described above), can possess significant hydrophobic, oleophobic and/or chemical resistance properties. Specifically, as a result of the hydrophobicity of the electrospun hydrophobic coaxial fiber 40, as well as the relatively rough surface morphology of the superhydrophobic coaxial fiber mat 50, the superhydrophobic coaxial fiber mat 50 formed from method 90 can be superhydrophobic. As discussed above, “superhydrophobic” refers to possessing a contact angle greater than or equal to 150° with water. For example, referring to
As mentioned above, the superhydrophobic coaxial fiber mat 50 may further be oleophobic and/or chemically resistant. As used herein, oleophobic refers to possessing an alkane contact angle greater than or equal to 90° with alkanes. For example, in one embodiment, the superhydrophobic coaxial fiber mat 50 possesses an alkane contact angle CA greater than or equal to 120° with alkanes. In another embodiment, the superhydrophobic coaxial fiber mat 50 possesses an alkane contact angle CA greater than or equal to 120° or 130° with alkanes. Also as used herein, “chemically resistant” refers to resisting chemical degradation due to contact with other chemicals. For example, the superhydrophobic coaxial fiber mat 50 may be chemically resistant to chemicals that would typically degrade or dissolve the electrospinnable polymer core 41 such as, for example, trifluoroethanol.
The method 90 for electrospinning an electrospun hydrophobic coaxial fiber 40 into a superhydrophobic coaxial fiber mat 50 may be conducted in any atmospheric conditions that allow for the electrospinning of the electrospun hydrophobic coaxial fiber 40 from the electrospinnable core solution 12 and the hydrophobic sheath solution 16. For example, the method 90 may be conducted at or about room temperature, at or about atmospheric pressure, in a standard environment or in an inert atmosphere, or variations thereof so long as the charged electrospinnable polymer can travel from the electrospinnable coaxial nozzle 10 to the collection plate 30 under the presence of the electric field such that the core solvent evaporates from the electrospinnable core solution and the sheath solvent evaporates from the hydrophobic sheath solution 16.
In the following exemplary method 90 of using a hydrophobic coaxial fiber electrospinning system 100, hydrophobic coaxial fibers were electrospun and collected to produce superhydrophobic coaxial fiber mats 50. The electrospinnable core solution 12 comprised 10 weight percent poly(∈-caprolactone) and 90 weight percent trifluoroethanol. For a first superhydrophobic coaxial fiber mat 50, the hydrophobic sheath solution 16 comprised 1 weight percent Teflon AF 2400 and 99 weight percent FC-75. For a second superhydrophobic coaxial fiber mat 50, the hydrophobic sheath solution 16 comprised 0.5 weight percent Teflon AF 2400 and 99.5 weight percent FC-75. The electrospinnable core solution 12 was ejected from the core outlet 13 of the electrospinning coaxial nozzle 10 at a core flow rate of about 1.5 mL/h. The hydrophobic sheath solution 16 was ejected from the sheath outlet 17 of the electrospinning coaxial nozzle 10 at a sheath flow rate of about 1.0 mL/h. The voltage applied between the electrospinning coaxial nozzle 10 and the collection plate 30 was about 12.5 kV. Finally, the electrospinnable coaxial nozzle 10 was separated from the collection plate 30 by a distance D of about 25 cm. The first superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 1 weight percent Teflon AF 2400) was measured to comprise 8.8 weight percent Teflon AF 2400 and the second superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 0.5 weight percent Teflon AF 2400) was measured to comprise 3.3 weight percent Teflon AF 2400.
The contact angle CA of the first superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 1 weight percent Teflon AF 2400) was measured for water to be 158° and the contact angle CA of the second superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 0.5 weight percent Teflon AF 2400) was measured for water to be 153°. For comparisons the contact angles CA between a poly(∈-caprolactone) film, a poly(∈-caprolactone) fiber mat, and a Teflon AF 2400 film were also determined. The contact angle CA of the poly(∈-caprolactone) film was measured for water to be 59°. The contact angle CA of the poly(∈-caprolactone) fiber mat was measured for water to be 125°. The contact angle CA of the Teflon AF 2400 film was measured for water to be 120°. Thus, not only were the contact angles CA for the superhydrophobic coaxial fiber mats 50 (158° and 153°) greater than the contact angle for the poly(∈-caprolactone) fiber mat (59°), but they were also significantly greater than the contact angles CA for the poly(∈-caprolactone) fiber mat (125°) and the Teflon AF 2400 film (120°).
Furthermore, rolling angles TA for the first superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 1 weight percent Teflon AF 2400), the second superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 0.5 weight percent Teflon AF 2400), the poly(∈-caprolactone) fiber mat, and the Teflon AF 2400 film were also determined. The rolling angle for the first superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 1 weight percent Teflon AF 2400), was measured to be about 7°. The rolling angle for the second superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 0.5 weight percent Teflon AF 2400), was measured to be about 20°. The rolling angle for the poly(∈-caprolactone) fiber mat was measured to greater than 90°. Finally, the rolling angle for the Teflon AF 2400 film was measured to be about 25°. Thus, both the first superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 1 weight percent Teflon AF 2400) and the second superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 0.5 weight percent Teflon AF 2400) showed increased dynamic hydrophobicity through improved rolling angles.
In addition, the oleophobic properties of the first superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 1 weight percent Teflon AF 2400) were compared to those of the poly(∈-caprolactone) fiber mat. When a 2 μL droplet of dodecane (˜23 mN/m) was placed on the poly(∈-caprolactone) fiber mat, the dodecane spread thoroughly and its alkane contact angle was almost 0°. However, when a 2 μL droplet of dodecane (˜23 mN/m) was placed on the first superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 1 weight percent Teflon AF 2400), the first superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 1 weight percent Teflon AF 2400) had an alkane contact angle CA of about 130°.
Finally, the mechanical properties of the first superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 1 weight percent Teflon AF 2400), the second superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 0.5 weight percent Teflon AF 2400), the poly(∈-caprolactone) fiber mat were determined. The first superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 1 weight percent Teflon AF 2400) was found to have an ultimate tensile strength (UTS) of 2.3 MPa, a maximum strain of 9.6 mm/mm and a stiffness of 13.0 MPa. The second superhydrophobic coaxial fiber mat 50 (hydrophobic sheath solution with 0.5 weight percent Teflon AF 2400) was found to have an ultimate tensile strength (UTS) of 2.23 MPa, a maximum strain of 8.5 mm/mm and a stiffness of 8.9 MPa. Finally, the poly(∈-caprolactone) fiber mat was found to have an ultimate tensile strength (UTS) of 3.1 MPa, a maximum strain of 6.3 mm/mm and a stiffness of 6.3 MPa. These measurements show that while the stiffness is increased for the first and second superhydrophobic coaxial fiber mats 50 (as a result of the addition of Teflon AF 2400), the mechanical properties of the core poly(∈-caprolactone) remained.
In the following exemplary method 90 of using a hydrophobic coaxial fiber electrospinning system 100, hydrophobic coaxial fibers were electrospun and collected to produce superhydrophobic coaxial fiber mats 50. The electrospinnable core solution 12 comprised 10 weight percent poly(∈-caprolactone) and 90 weight percent trifluoroethanol. For the superhydrophobic coaxial fiber mat 50, the hydrophobic sheath solution 16 comprised 1 weight percent Teflon AF 2400 and 99 weight percent FC-75. The electrospinnable core solution 12 was ejected from the core outlet 13 of the electrospinning coaxial nozzle 10 at a core flow rate of about 1.5 mL/h. The hydrophobic sheath solution 16 was ejected from the sheath outlet 17 of the electrospinning coaxial nozzle 10 at a sheath flow rate of about 1.0 mL/h. The voltage applied between the electrospinning coaxial nozzle 10 and the collection plate 30 was about 13 kV. Finally, the electrospinnable coaxial nozzle 10 was separated from the collection plate 30 by a distance D of about 25 cm. Trifluoroethanol vapor was then applied to the superhydrophobic coaxial fiber mat 50 and micrographs were taken at 0 minute (
Conversely, an electrospun poly(∈-caprolactone) fiber mat was also subjected to trifluoroethanol vapor. As shown in
It should now be appreciated that superhydrophobic coaxial fiber mats can be formed by electrospinning hydrophobic coaxial fibers from electrospinnable core solutions and hydrophobic sheath solutions. The hydrophobic sheath solution, which may not be electrospinnable on its own due to a low dielectric constant, can be electrospun in combination with the electrospinnable core solution to provide an efficient method for producing hydrophobic coaxial fibers. Furthermore, as a result of the hydrophobic material and the morphology of the collected hydrophobic coaxial fibers, the superhydrophobic coaxial fiber mats can possess increased hydrophobic, oleophobic and/or chemical resistance properties.
It is noted that the terms “substantially” and “about” may be utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.
While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications may be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.
This application claims the benefit of U.S. Provisional Application No. 61/180,284, filed May 21, 2009, which application is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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61180284 | May 2009 | US |