Chemically-functionalized spun-bond nylon nonwoven and methods of making and using the same

Abstract

Described herein is a chemically-functionalized spun-bond nylon nonwoven and a method of making, wherein a homogeneous nylon spun-bond fiber is chemically-functionalized with an aqueous reaction mixture comprising an aminoalkyl (meth)acryloyl monomer. Such chemically-functionalized nonwovens disclosed herein may be used to filter fluids.

Description

CHEMICALLY-FUNCTIONALIZED SPUN-BOND NYLON NONWOVEN AND METHODS OF MAKING AND USING THE SAME TECHNICAL FIELD

[0001] The present disclosure relates to functionalized spun-bond nylon nonwovens, and methods for preparing the same. The present disclosure further relates to a filter using the functionalized nonwoven and a method of filtering a fluid. The functionalized nonwoven is useful in selectively filtering and removing biological materials, such as bio contaminates, from biological samples. SUMMARY

[0002] There is a desire to identify grafted substrates which have high functionalization while having minimum dimensional change during use.

[0003] In one aspect, a chemically-functionalized nonwoven is disclosed. The chemically-functionalized nonwoven comprising: a spun-bond nonwoven comprising a plurality of homogeneous fibers, wherein the plurality of homogeneous fibers comprise nylon, and wherein at least a portion of the plurality of homogeneous fibers are chemically-functionalized with an aqueous reaction mixture comprising an aminoalkyl (meth)acryloyl monomer.

[0004] In some embodiments, the aqueous reaction mixture further comprises a hydrophilic monomer.

[0005] In some embodiments, wherein the aqueous reaction mixture is substantially free of poly(alkylene oxide) monomer.

[0006] In another aspect, a nonwoven is described comprising a chemically-functionalized nonwoven, wherein the chemically-functionalized nonwoven comprises: a spun-bond nonwoven comprising a plurality of homogeneous fibers, wherein the plurality of homogeneous fibers comprise nylon, and wherein at least a portion of the plurality of homogeneous fibers are chemically-functionalized with an aqueous reaction mixture comprising an aminoalkyl (meth)acryloyl monomer.

[0007] In yet another aspect, a filtration media is described comprising a chemically-functionalized nonwoven, which comprises: a spun-bond nonwoven comprising a plurality of homogeneous fibers, wherein the plurality of homogeneous fibers comprise nylon, and wherein at least a portion of the plurality of homogeneous fibers are chemically-functionalized with an aqueous reaction mixture comprising an aminoalkyl (meth)acryloyl monomer.

[0008] In still another aspect, a method of making a chemically-functionalized nonwoven is described, the method comprising: providing a spun-bond nonwoven wherein the spun-bond nonwoven comprises a plurality of homogeneous fibers, wherein the plurality of homogeneous fibers comprise nylon; and contacting the spun-bond nonwoven with an aqueous reaction mixture comprising:an aminoalkyl (meth)acryloyl monomer; optionally, a hydrophilic monomer; and optionally, a (meth)acryloyl epoxide monomer; and exposing the spun-bond nonwoven to radiation.

[0009] The above summary is not intended to describe each embodiment. The details of one or more embodiments of the invention are also set forth in the description below. Other features, objects, and advantages will be apparent from the description and from the claims. DETAILED DESCRIPTION

[0010] As used herein, the term “a”, “an”, and “the” are used interchangeably and mean one or more; and “and / or” is used to indicate one or both stated cases may occur, for example A and / or B includes, (A and B) and (A or B); “(meth)acrylate” refers to compounds containing either an acrylate (CH2=CHCOOR) or a methacrylate (CH2=CCH3COOR) structure or combinations thereof; and “monomer” is a molecule which can undergo polymerization which then form part of the essential structure of a polymer. “Alkyl” means a linear or branched, cyclic or acyclic, saturated monovalent hydrocarbon having from one to about twelve carbon atoms, e.g., methyl, ethyl, 1-propyl, 2-propyl, pentyl, and the like. “Alkylene” means a linear saturated divalent hydrocarbon having from one to about twelve carbon atoms or a branched saturated divalent hydrocarbon having from three to about twelve carbon atoms, e.g., methylene, ethylene, propylene, 2-methylpropylene, pentylene, hexylene, and the like. “Aryl” means a monovalent aromatic, such as phenyl, naphthyl and the like.

[0011] Also herein, recitation of ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0012] Also herein, recitation of “at least one” includes all numbers of one and greater (e.g., at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.).

[0013] As used herein, “comprises at least one of” A, B, and C refers to element A by itself, element B by itself, element C by itself, A and B, A and C, B and C, and a combination of all three.

[0014] In the present disclosure, it has been found that when chemically functionalizing a nylon fiber with an aqueous reaction mixture disclosed herein, the spun-bond nylon nonwoven has more monomer derivatized onto it and better binding capacity than a polypropylene nonwoven. Further, the derivatized nylon spun-bond nonwoven offers better dimensional stability than a nylon melt blown fiber. Such nylon spun-bond fiber may be used in a nonwoven format, which in some embodiments, could be used as a filtration media.

[0015] The fibers of the present disclosure are homogeneous fibers comprising nylon. As used herein “homogeneous fibers” refer to fibers that have a homogeneous composition across the diameter and length of the fibers. The fibers comprise nylon and can include a nylon copolymer or blend of nylon with another polymer and / or additive.

[0016] Exemplary nylons include: nylon 6; nylon 6,6; nylon 1,6; nylon 11; nylon 12; nylon 4,6; nylon 4; nylon 1,4; nylon 510, nylon TMDT (or nylon 6,3,T), or combinations thereof.

[0017] The fibers of the present disclosure may have a circular cross-section, however, other cross- sections may also be used such as, for example, triangular, square, rectangular, pentagonal, hexagonal, heptagonal, octagonal, star-shaped, oval, trilobal, and tetralobal.

[0018] The fibers used in practice of the present disclosure may have any average fiber diameter, and may be continuous, random, and / or staple fibers. For example, in some embodiments, the fibers (i.e., individual fibers) may have an average fiber diameter (for example, average effective diameter) of at least 5, 8, or even 10 micrometers and at most 12, 15, 18, 20, 22 or even 25 micrometers.

[0019] The diameter of the fiber may be measured using techniques known in the art. In some embodiments, the diameter of the fiber can be determined by microscopy (e.g., optical or scanning electron microscopy), wherein the fiber is cross-sectioned and viewed under magnification to determine the diameter of the fiber. In some embodiments, the diameter of the fiber can be calculated by measuring the pressure drop across a fiber web. The effective fiber diameter (EFD) can be calculated as described in the Example Section below.

[0020] The spun-bond fibers described herein can generally be made using techniques known in the art for making filaments. In melt spinning, a polymer is heated, passed through a spinneret, and fibers solidify upon cooling. The term "meltspun" as used herein refers to fibers that are formed by extruding molten fibers out of a set of orifices and allowing the fibers to cool and (at least partially) solidify to form fibers, with the fibers passing through an air space (which may contain streams of moving air) to assist in cooling and solidifying the fibers, and with the thus-formed fibers then passing through an attenuation (i.e., drawing) unit to draw the fibers.

[0021] In some embodiments, a spun-bond fibers are in a nonwoven format. As used herein, the term “nonwoven” refers to a fabric that has a structure of individual fibers, which are randomly and / or unidirectionally interlaid in a mat-like fashion. The nonwoven substrate may be manufactured by any of the commonly known processes for producing nonwoven webs.

[0022] Spun-bonded nonwoven fibrous webs can be formed according to well-known conventional methods wherein melt-spun fibers are deposited on a moving belt where they form a nonwoven continuous fiber web having interfiber bonds.

[0023] In some embodiments, a nonwoven web can be made by air-laying of spun-bond fibers. Air-laid nonwoven fibrous webs may be prepared using equipment such as, for example, that available as a RANDO WEBBER from Rando Machine Company of Macedon, New York. In some embodiments, atype of air-laying may be used that is termed gravity-laying, as described, e.g., in U. S. Pat. Publ. No. 2011 / 0247839 (Lalouch et al.) the disclosure of which is incorporated by reference herein. Nonwoven fibrous webs may be densified and strengthened, for example, by techniques such as crosslapping, stitchbonding, needletacking, hydroentangling, chemical bonding, and / or thermal bonding.

[0024] Nonwoven fibrous webs according to the present disclosure may have any basis weight, thickness, porosity, and / or density unless otherwise specified. In one embodiment, the nonwovens have a basis weight of at least 50, 60, 80, or even 100 grams per square meter (g / m2); and at most 150, 200, 225, or even 250 grams per square meter.

[0025] In the present disclosure, spun-bond fibers such as described above, are contacted with an aqueous reaction mixture and subjected to radiation to react the monomers to the fiber.

[0026] In the present disclosure, the spun-bond fiber is exposed to an aqueous mixture of monomers, which are then reacted together to functionalize the fibers with amine groups, which can include quaternary ammonium groups.

[0027] The aqueous reaction mixture comprises an aminoalkyl (meth)acryloyl monomer; optionally, a hydrophilic monomer, and optionally, a (meth)acryloyl epoxide monomer.

[0028] The aminoalkyl (meth)acryloyl monomers are amino (meth)acrylates or amino (meth)acrylamides of Formula I or quaternary ammonium salts thereof I methyl; L is —O— or —NH—; and Y is an alkylene(e.g., an alkylene having 1 to 10 carbon atoms, 1 to 6, or 1 to 4 carbon atoms). Each R2is independently hydrogen or alkyl, preferably C1-C4 alkyl. Alternatively, the two R2groups taken together with the nitrogen atom to which they are attached can form a heterocyclic group that is aromatic, partially unsaturated (i.e., unsaturated, but not aromatic), or saturated, wherein the heterocyclic group can optionally be fused to a second ring that is aromatic (e.g., benzene), partially unsaturated (e.g., cyclohexene), or saturated (e.g., cyclohexane). The counter ions of the quaternary ammonium salts are often halides, sulfates, phosphates, nitrates, and the like. Such monomers may be quaternary ammonium monomers, i.e., having a -N(R2)3+X−group, wherein each R2is as defined, and X−is the counter anion. Such monomers having a quaternary ammonium group may be directly reacted to the fiber or an aminoalkyl (meth)acryloyl monomer, having a primary, secondary or tertiary amine group, may be reacted to the fiber and subsequently converted to a quaternary ammonium group by alkylation.

[0029] In some embodiments of Formula I, both R2groups are hydrogen. In other embodiments, one R2group is hydrogen and the other is an alkyl having 1 to 10, 1 to 6, or 1 to 4 carbon atoms. In yet other embodiments, the R2groups combine with the nitrogen atom to which they are attached to form a heterocyclic group. The heterocyclic group includes at least one nitrogen atom and can contain otherheteroatoms such as oxygen or sulfur. Exemplary heterocyclic groups include, but are not limited to imidazolyl. The heterocyclic group can be fused to an additional ring such as a benzene, cyclohexene, or cyclohexane. An exemplary heterocyclic group fused to an additional ring can include benzoimidazolyl.

[0030] In one embodiment, the aminoalkyl (meth)acryloyl monomers of formula (I) is a quaternary ammonium salt as in Formula II: preferably methyl; L is –O- or –NH-; and Y is an alkylene (e.g., anatoms, 2 to 6, or 2 to 4 carbon atoms). R2, R3, and R4, are independently aryl or alkyl, preferably C1-C4alkyl; and X- is the counter anion.

[0031] Exemplary quaternary salts of the aminoalkyl (meth)acryloyl monomers include, but are not limited to, (meth)acrylamidoalkyltrimethylammonium salts (e.g., 3- methacrylamidopropyltrimethylammonium chloride and 3-acrylamidopropyltrimethylammonium chloride) and (meth)acryloxyalkyltrimethylammonium salts (e.g., 2-acryloxyethyltrimethylammonium chloride, 2-methacryloxyethyltrimethylammonium chloride, 3-methacryloxy-2- hydroxypropyltrimethylammonium chloride, 3-acryloxy-2-hydroxypropyltrimethylammonium chloride, and 2-acryloxyethyltrimethylammonium methyl sulfate).

[0032] In some embodiments, the aqueous reaction mixture comprises at least 10, 20, 25, 30, 40, or even 50 % by weight of an aminoalkyl (meth)acryloyl monomer versus the total monomers. In some embodiments, the aqueous reaction mixture comprises at most 55, 60, 70, 80, 90, 95, 98, 99, or even 100% by weight of an aminoalkyl (meth)acryloyl monomer versus the total monomers.

[0033] In some embodiments, the aqueous solution also includes a hydrophilic monomer, which is an ethylenically-unsaturated compound that has hydrophilic character. As used herein “hydrophilic monomers” are those polymerizable monomers having a water miscibility (water in monomer) of at least 1 wt. %, preferably at least 5 weight % without reaching a cloud point, are exclusive of poly(alkylene oxide) monomers and contain no acidic functional groups or groups that would retard the functionalizing polymerization.

[0034] Examples of suitable hydrophilic monomers include 2-hydroxyethyl(meth)acrylate (HEMA), 2- ethoxyethyl methacrylate (2-EOEMA), 2-hydroxypropyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, 4-hydroxybutyl(meth)acrylate, N-vinyl caprolactam, N-vinyl acetamide, N-vinyl pyrrolidone, acrylonitrile, tetrahydrofurfuryl acrylate, acrylamide, mono- or di-N- alkyl substituted acrylamide, glycerol methacrylate, and combinations thereof. Preferred polar monomers include 2-hydroxyethyl(meth)acrylate (HEMA), N-vinyl pyrrolidone, N-vinyl acetamide, methylacrylamide, and mixtures thereof.

[0035] In some embodiments, the aqueous reaction mixture comprises at least 0.5, 1, 2, 10, 20, 25, 30, 40, or even 50 % by weight of a hydrophilic monomer versus the total monomers. In some embodiments, the aqueous reaction mixture comprises at most 55, 60, 70, 80, 90, or even 95 % by weight of a hydrophilic monomer versus the total monomers.

[0036] In some embodiments, the aqueous reaction mixture includes a (meth)acryloyl epoxide monomer, in other words a (meth)acrylate monomer with an epoxide substituent. Exemplary (meth)acryloyl epoxide monomers include: glycidyl methacrylate and glycidyl acrylate.

[0037] In some embodiments, the aqueous reaction mixture comprises at least 0.1, 0.5, 1, 1.5, 2, or even 2.5 % by weight of a (meth)acryloyl epoxide monomer versus the total monomers. In some embodiments, the aqueous reaction mixture comprises at most 20, 15, 10, 5, or even 3 % by weight of a (meth)acryloyl epoxide monomer versus the total monomers.

[0038] In some embodiments, the aqueous reaction mixture comprises a monofunctional ethylenically- unsaturated monomer having a poly(alkylene oxide) group. Such poly(alkylene oxide) monomer may be of the Formula: Z-Q-(CH(R5)—CH2-Q)m-R6, III wherein Z is a polymerizable ethylenically unsaturated moiety, R5is a H or a C1to C4alkyl group, R6is a H, a C1to C4alkyl group, aryl group, or combinations thereof and m is from 2 to 100, preferably 5 to 20, and Q is a divalent linking group selected from —O—, —NR1—, —CO2— and —CONR1.

[0039] In one embodiment, the poly(alkylene oxide) group is a poly(ethylene oxide) (co)polymer. In another embodiment, the pendent poly(alkylene oxide) group is a poly(ethylene oxide-co-propylene oxide) copolymer. Such copolymers may be block copolymers, random copolymers, or gradient copolymers.

[0040] Useful ethylenically unsaturated moiety, Z, of the monomer may include:wherein R3is H or -CH3and r=1-10.

[0041] The monomer having a poly(alkylene oxide) group can be prepared, for example, by reacting mono- or di-functional alkylene oxide (co)polymers (which are typically commercially available) with reactive ethylenically unsaturated compounds (e.g., acrylates). The functional groups terminating the poly(alkylene oxide) may include hydroxy groups, amine groups and carboxy groups. A variety ofreactive ethylenically unsaturated compounds such as acrylate derivatives can be used including, but not limited to, (meth)acrylic acid, (meth)acryloyl chloride, (meth)acrylic anhydride, and 2-isocyanatoethyl (meth)acrylate. Preferably, the monomer is prepared by reacting the mono- or di-functional alkylene oxide (co)polymer with (meth)acrylic anhydride. Typically, if a stoichiometric amount of the ethylenically unsaturated reactant is combined with the monofunctional alkylene oxide (co)polymer (such as a monohydroxy terminated alkylene oxide (co)polymer), 100% conversion to the monosubstituted product is obtained.

[0042] Examples of suitable monofunctional poly(alkylene oxide) monomers include poly(ethylene oxide) (meth)acrylate, poly(propylene oxide) (meth)acrylate, poly(ethylene oxide-propylene oxide) (meth)acrylate, and combinations thereof. Such monomers preferably include one nonreactive end group such as (C1-C4)alkoxy, aryloxy (e.g., phenoxy), and (C1-C4)alkaryloxy. These groups can be linear or branched. These monomers can be of a wide range of molecular weights and are commercially available from sources such as Sartomer Company, Exton, Pa.; Shinnakamura Chemical Co., Ltd., Tokyo, Japan; Aldrich, Milwaukee, Wis.; and Osaka Organic Chemical Ind., Ltd., Osaka, Japan.

[0043] In some embodiments, the aqueous reaction mixture is substantially free of these monomers comprising poly(alkylene oxide) groups. As used herein, substantially free means less than 10, 8, 5, 2, 1, 0.5, or even 0.1 weight % or even none versus the total weight of the monomers.

[0044] The reaction mixture is aqueous meaning that the mixture comprises water and / or water miscible organic solvents. In some embodiments, the water miscible solvents are protic group-containing organic liquids such as the lower alcohols having 1 to 4 carbon atoms, lower glycols having 2 to 6 carbon atoms, and most preferably lower glycol ethers having 3 to 6 carbon atoms and 1 to 2 ether linkages. In some embodiments higher glycols such as poly(ethylene glycol) may be used. Any such water miscible organic solvent preferably has no tertiary hydrogen atoms, or other groups that would retard the polymerization of the monomers and their reaction with the fiber. Exemplary water miscible solvents include: methanol, ethanol, n-butanol, t-butyl alcohol, ethylene glycol, methoxyethanol, ethoxyethanol, propoxyethanol, butoxyethanol, methyl carbitol, ethyl carbitol, and mixtures thereof. In some embodiments, non-protic water miscible organic solvents that can also be used such as aliphatic esters and ketones and sulfoxides such as ethyl acetate, propyl acetate, butyl acetate, methoxyethyl acetate, ethoxyethyl acetate, propoxyethyl acetate, butoxyethyl acetate, triethyl phosphate, acetone, methyl ethyl ketone, methyl propyl ketone and dimethyl sulfoxide.

[0045] The ratio of water to organic solvent can vary, but is typically greater than 1:1 (v / v) water to organic solvent, preferably greater than 5:1, and more preferably greater than 7:1.

[0046] Typically, the total concentration of the monomers in the aqueous reaction mixture ranges from at least 1, 2, 5, or even 10 wt % and at most 50, 45, 40, 30, 25, 20, or even 15 wt % based on a total weight of the aqueous reaction mixture.

[0047] In some embodiments, the amount of aqueous reaction mixture is at least 30, 35, 40, or even 45 g to at most 100, 90, 80, 70, 60, or even 50 g per 100 gsm of spun-bond fiber.

[0048] Irradiation is used to initiate the polymerization of the monomer reaction mixture and its reaction with the spun-bond fiber.

[0049] The irradiation step comprises the ionizing irradiation of fibers, preferably with ionizing e-beam or gamma radiation to prepare free radical reaction sites with which the fibers are subsequently derivatized with the aqueous reaction mixture. “Ionizing irradiation” means radiation of a sufficient dosage and energy to cause the formation of free radical reaction sites in the base substrate. Ionizing radiation may include gamma, electron-beam, x-ray and other forms of electromagnetic radiation. In some instances, corona radiation can be sufficiently high energy radiation. The radiation is sufficiently high energy, that when absorbed by the fiber, sufficient energy is transferred to that fiber to result in the cleavage of chemical bonds in that fiber and the resultant formation of free radical sites on the fiber.

[0050] In the irradiation step, the fiber is exposed to a sufficient quantity of ionizing radiation, so as to form free radicals in the fiber. The chamber may contain at least one device capable of providing a sufficient dose of radiation. A single device is capable of providing a sufficient dose of radiation, although two or more devices, and / or multiple passes through a single device, may be used. The environment containing the fiber comprises an inert atmosphere such as nitrogen, carbon dioxide, helium, argon, etc. with a minimal amount of oxygen, which is known to inhibit free-radical polymerization.

[0051] Dose is the total amount of energy absorbed per mass unit. Dose is commonly expressed in kiloGrays (kGy). A Gray is defined as the amount of radiation required to supply 1 joule of energy per kilogram of mass. The total dose received by the fiber depends on a number of parameters including source activity, residence time (i.e., the total time the sample is irradiated), the distance from the source, and attenuation by the intervening cross-section of materials between the source and sample. Dose is typically regulated by controlling residence time, distance to the source, or both.

[0052] Total dose requirement for any given composition will vary as a function of desired monomer selected, fiber used, and the dose rate. In one embodiment, the doses ranged from about 20 to 100 kGy. Thus, a dose rate can be selected based on desired properties for a specified composition. The dose rate is typically in the range of 0.0005 kGy / sec (gamma) to 200 kGy / sec (E-beam).

[0053] Electron beam is one preferred method due to the ready availability of commercial sources. Electron beam generators are commercially available from a variety of sources, including the ESI “ELECTROCURE” EB SYSTEM from Energy Sciences, Inc. (Wilmington, Mass.), and the BROADBEAM EB PROCESSOR from PCT Engineered Systems, LLC (Davenport, Iowa). For any given piece of equipment and irradiation sample location, the dosage delivered can be measured in accordance with ASTM E-1275 entitled “Practice for Use of a Radiochromic Film Dosimetry System.” By altering extractor grid voltage, beam diameter and / or distance to the source, various dose rates can be obtained.

[0054] Other sources of irradiation may be used with equal derivatizing performance, a desirable source of ionizing radiation comprises an electron beam source because the electron beam can produce high and fast dose delivery rates. Electron beams (e-beams) are generally produced by applying high voltage to tungsten wire filaments retained between a repeller plate and an extractor grid within a vacuum chamber maintained at about 10−6Torr. The filaments are heated at high current to produce electrons. The electrons are guided and accelerated by the repeller plate and extractor grid towards a thin window of metal foil. The accelerated electrons, traveling at speeds in excess of 107meters / second (m / sec) and possessing about 100 to 300 kilo-electron volts (keV), pass out of the vacuum chamber through the foil window and penetrate whatever material is positioned immediately beyond the foil window.

[0055] The quantity of electrons generated is directly related to the current. As extractor grid voltage is increased, the acceleration or speed of electrons drawn from the tungsten wire filaments increase. E-beam processing can be extremely precise when under computer control, such that an exact dose and dose rate of electrons can be directed against the fiber.

[0056] The temperature within the chamber is desirably maintained at an ambient temperature by conventional means. Without intending to be limited to any particular mechanism, it is believed that the exposure of the fiber to an electron beam results in free radical sites in the substrate which can then subsequently react with the monomers in the aqueous reaction mixture.

[0057] The total dose received by substrate primarily affects the number of radical sites formed and subsequently the extent to which the monomers are reacted with the fiber. Dose is dependent upon a number of processing parameters, including voltage, web- or line-speed and beam current. Dose can be conveniently regulated by controlling line speed (i.e., the speed with which the nonwoven substrate passes under the irradiation device), and the current supplied to the extractor grid. A target dose (e.g., <10 kGy) can be conveniently calculated by multiplying an experimentally measured coefficient (a machine constant) by the beam current and dividing by the web speed to determine the exposure. The machine constant varies as a function of beam voltage.

[0058] While the controlled amount of electron beam radiation exposure is dependent upon the residence time, the fiber is subjected to a controlled amount of dosage ranging from a minimum dosage of about 1 kilogray (kGy) to a practical maximum dosage of less than about 200 kGy, depending on the particular polymer. Generally, suitable gamma ray sources emit gamma rays having energies of 400 keV or greater. Typically, suitable gamma ray sources emit gamma rays having energies in the range of 500 keV to 5 MeV. Examples of suitable gamma ray sources include cobalt-60 isotope (which emits photons with energies of approximately 1.17 and 1.33 MeV in nearly equal proportions) and cesium-137 isotope (which emits photons with energies of approximately 0.662 MeV). The distance from the source can be fixed or made variable by changing the position of the target or the source. The flux of gamma rays emitted from the source generally decays with the square of the distance from the source and duration of time as governed by the half-life of the isotope.

[0059] In the instant method, the irradiated fiber, having free radical sites in the fiber, are contacted with the aqueous reaction mixture subsequent to and not concurrent with, the irradiation step. The free radical sites generated in the fiber have average lifetimes ranging from several minutes to several hours and progressively decay to a low concentration within about ten hours at room temperature. Lower temperatures, such as dry ice temperatures, promotes longer radical lifetimes. Alternatively, humidification and nitrous oxide can increase the rate of substrate radical formation via generation of hydroxyl radicals.

[0060] Generally, the irradiated fiber is contacted with the aqueous reaction mixture immediately after the irradiation step. Generally, when using E-beam the irradiated fiber is imbibed within an hour, preferably within ten minutes.

[0061] The fiber can be contacted with the aqueous reaction mixture using techniques known in the art including, but are not limited to, a spray coating, flood coating, knife coating, Meyer bar coating, dip coating, and gravure coating.

[0062] The aqueous reaction mixture remains in contact with the fiber for a time sufficient for the radical sites to initiate polymerization with the monomers. When contacted with a solution of monomers, reactions are mostly completed after 12 hours exposure; generally about 90+ percent. As a result, the fiber comprises polymers and / or copolymers attached to the interstitial, the outer surfaces and within the fiber.

[0063] Generally, the total monomer content functionalized onto the fiber may be from 0.5 to 5 times the weight of the fiber.

[0064] Once the fiber has been contacted with the aqueous reaction mixture for a desired period of time, the fiber functionalized with the polymer groups may be optionally rinsed to remove residual monomer and / or dried.

[0065] In the optional rinsing step, the chemically-functionalized fiber is washed or rinsed one or more times to remove any unreacted monomers, solvent or other reaction by-products. Typically, the functionalized fiber is washed or rinsed up to three times using a water rinse, an alcohol rinse, a combination of water and alcohol rinses, and / or a solvent rinse (e.g., acetone, methyl ethyl ketone, etc.). When an alcohol rinse is used, the rinse may include one or more alcohols including, but not limited to, isopropanol, methanol, ethanol, or any other alcohol that is practical to use and an effective solvent for any residual monomer. In each rinse step, the functionalized fiber may pass through a rinse bath or a rinse spray. In some embodiments, the rinse may comprise an ionic buffer solution that would reduce swelling of the resulting polymer, the amount of retained water, and also avoiding weakening the chemically- functionalized nonwoven during this rinse step.

[0066] In the optional drying step, the functionalized fiber is dried to remove any rinse solution. Typically, the functionalized fiber is dried in an oven having a relatively low oven temperature for a desired period of time (referred to herein as “oven dwell time”). Oven temperatures typically range from about 60°C to about 120°C, while oven dwell times typically range from about 8 to about 72 hours. Anyconventional oven may be used in the optional drying step. It should also be noted that in other embodiments the drying step can proceed before the rinsing step to eliminate volatile components before extraction of non-reacted residue. Following the optional drying step, the dried functionalized fiber can be taken up in roll form to be stored for future use.

[0067] In some embodiments, the chemically-functionalized nonwovens as disclosed herein has a gain in mass by at least 75, 100, 150, 200, or even 250 %. Typically, the chemically-functionalized nonwovens are limited to a gain in mass of no more than 300 or even 350% to maintain structural integrity.

[0068] In some embodiments, the chemically-functionalized nonwovens as disclosed herein has a surface area as determined in the example section of at least 1, 1.2, 1.3, or even 1.4 m2and at most 2.0, 1.8, 1.6, or even 1.5 m2.

[0069] Derivatized nonwovens can be made using web processing. In other words, in a factory long sheets of nonwoven can be passed through rollers, through coaters and ovens to quickly achieve a roll good that subsequently can be unrolled and cut into discrete articles. In some embodiments these articles can be placed within a housing and used for among other things, separation of purification of aqueous- based substances. As can be seen in the Example Section below, when the nonwovens are boiled in water for 1 hour, they can swell. This swelling can change the dimensions of the nonwoven, which may cause issues in processing and / or during use. As may be seen in the Example Section below, the changes in dimension may not be uniform, with the article changing more in one direction (e.g., length) versus another (e.g., width). Unexpectedly, it has been discovered in the present disclosure that the spun-bond nonwoven appears to have minimal change in dimension during this 1 hour boiling in water. In some embodiments, the articles of the present disclosure have a percent area change of less than 25, 20, 15, or even 10 %.

[0070] Due to the increased efficiency of derivatization, in some embodiments, the chemically- functionalized nonwovens as disclosed herein, have an improved ability to capture analytes of interest. For example, in some embodiments, the nonwovens of the present disclosure have a binding capacity of at least 350, 375, 400, 425, or even 450 mg / g for metanil yellow.

[0071] In some embodiments, the chemically-functionalized nonwovens disclosed herein may be used for example, in filtration applications, such as filtering large molecules from fluids. For example, purification or isolation of biological materials. EXAMPLES

[0072] Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight, and all reagents used in the examples were obtained, or are available, from general chemical suppliers such as, for example, Sigma-Aldrich Company, Saint Louis, Missouri, or may be synthesized by conventional methods.

[0073] These abbreviations are used in the following examples: cm = centimeter, g = grams, gsm = grams per square meter, ghm = gram per hole per minute, hr = hour,oC = degrees Celsius, in = inch, kV = kiloVolt, lpm = liters per minute, mA = milliamp, mg = milligram, MRad = megaradian, min = minute, m = meter, mm = millimeter, mM = millimolar, mL = milliliter, nm = nanometer, Pa = Pascal, psi = pounds per square inch, ppm = parts per million, oz = ounce, and sec = second. Materials Name Description MAPTAC [3- (methacryloylamino)propyl] trimethylammonium chloride monomer obtained under the trade designation “Visiomer-MAPTAC ” from Evonik, Essen, Germany NVP N-vinylpyrrolidone monomer obtained under the trade designation “V3409” from Sigma-Aldrich Co. GMA Glycidyl methacrylate monomer obtained under the trade designation “141238” from Sigma-Aldrich Co. MAETAC [2-(Methacryloyloxy)ethyl]trimethylammonium chloride monomer at 80% in water obtained under the trade designation “408107” from Sigma-Aldrich Co. AETAC [2-(Acryloyloxy)ethyl]trimethylammonium chloride monomer at 80% in water obtained under the trade designation “496146” from Sigma-Aldrich Co. PP Polypropylene isotactic homopolymer resin obtained under the trade designation “3860X” from Total Petrochemicals & Refining, USA, Inc., Houston, TX. Nylon Nylon 6 obtained under the trade designation “Ultramid B27 E” from BASF. Metanil Sodium 3-[(4-anilinophenyl)diazenyl]benzenesulfonate obtained under the trade yellow designation “Metanil Yellow” from ACROS Organics, Antwerp, Belgium.

[0074] Method of Making a Spun-bond (SB) Nonwoven Comprising Fibers

[0075] Nonwoven media substrates were produced on a spun-bond 0.5 m lab line having a 2.5 in (6.35 cm) single screw extruder with planetary melt pump to meter polymer flow to a spin pack assembly. Single-component fibers were produced accordingly. The process was similar to that described in U.S. Pat. No.6,916,752 (Berrigan et al.). Polymer melt(s) entered the pack and were distributed evenly and filtered before reaching the spinneret orifices where the filaments were extruded.

[0076] Filaments (or fibers) were formed as the polymer (Nylon or PP) exited the spinneret at the bottom of the pack and were drawn vertically through a quench zone fed with chilled air into an attenuator supplied with compressed air. The filaments were then laid down on a moving collector belt forming a nonwoven web and held in place by vacuum until passing through a bonding zone where the nonwoven web was taken up on a surface winder. Nylon spun-bond and PP spun-bond were prepared using same equipment with different temperature setting.

[0077] Method of Making a Melt Blown (BMF) Nonwoven Comprising Fibers

[0078] The nonwoven melt blown webs were prepared using a conventional melt blowing process consisting of a 50.8 mm diameter single screw extruder equipped with a resin drying hopper. The output of the extruder was fed into a 10 cm3 / revolution meter gear pump which delivered the polymer melt into a 318 mm wide, multi-row, nozzle die available under the trade designation “SPUN-BLOWN” by the BiaxFiberfilm Corporation of Neenah, WI. The spinneret of the die had 14 rows total. The outer-most rows on each side emitted hot, compressed air while the middle 12 rows emitted molten polymer which was attenuated into the melt blown fibers by hot, compressed air. The fibers from the array of nozzles were quenched using a water mist spray. The fibers were collected on a flat, stainless steel, mesh belt collector that had vacuum suction on the back side of the belt, and then wound into a roll. The rows of the nozzles of the die spinnerette had a spacing of 1.78 mm center-to-center and the nozzle spacing within a row was 1.78 mm center-to-center. The nozzles had an inside diameter of 0.38 mm.

[0079] The water mist spray was used to quench the stream of molten fibers. The water mist spray was produced using high pressure, water misting nozzles supplied by Aeromist Inc. of Phoenix, AZ. The water misting nozzles had an orifice size of 0.152 mm and were spaced at 38.1 mm center-to-center on stainless steel, distribution pipes. A water misting distribution pipe was used on each side of the molten fiber stream. Deionized water was fed to the misting nozzles at 500 psi.

[0080] Pressure Drop Test

[0081] A high-speed automated filter tester (8130 from TSI Inc., Shoreview, MN) was operated with particle generation and measurement turned off. Flowrate was adjusted to 85 lpm and a 5.25 in (13.34 cm) diameter sample was used. The sample was placed onto the lower circular plenum opening and the tester was engaged. A pressure transducer (MKS Instruments, Inc., Andover, MA) within the device measured the pressure drop (delta P) in mm water.

[0082] Method of Measuring Effective Fiber Diameter (EFD)

[0083] The EFD was calculated from a pressure drop (measured using the “Pressure Drop Test” described herein), a thickness and a face velocity of 5.3 cm / sec. The sample thickness of a 5.25 in (13.34 cm) disc was measured using a thickness testing gauge having a tester foot with dimensions of 5 cm x 12.5 cm at an applied pressure of 150 Pa. Based on the measured pressure drop, the Effective Fiber Diameter in microns was calculated as set forth in C.N. Davies, The Separation of Airborne Dust and Particulates, Institution of Mechanical Engineers, London Proceedings, IB (1952).

[0084] Scanning Electron Microscopy (SEM)

[0085] Fiber dimensions and cross sections were examined using a scanning electron microscope (Hitachi TM4000Plus from NCI Inc., Brooklyn Park, MN). Cross sections were prepared by freeze fracturing samples with liquid nitrogen. A thin layer of gold was sputter coated on the samples to make them conductive.

[0086] Actual Fiber Diameter (or AFD)

[0087] An optical microscope (ECLIPSE E600POL from Nikon, Tokyo, Japan) with a digital camera (DMC5400 from Leica Microsystems, Bloomington, MN) was used for optically imaging the fibers in the spun-bond nonwovens. For conditions of interest, a fiber bundle was collected below the attenuator, a cross section prepared, and a multi-focus image was obtained with the optical microscope at 50 or 100x magnification (exact magnification was chosen as needed to obtain approximately 30 measurements froma single image). Fibers were then measured manually where edge detection was assisted by the associated Leica Application Suite X v3.0.9.19082 software (from Leica Microsystems, Bloomington, MN).

[0088] Electron Beam (EB) Derivatization Procedure

[0089] Fibers were derivatized as follows: Aqueous reaction mixtures (as described in the examples) were prepared in 4 oz (118 mL) tight-capped jars to a total volume of 60-100 mL. After the mixture was made, the jars were shaken by hand and sparged with house nitrogen. The jars were then transferred to the nitrogen-containing glove box and uncapped until the glove box oxygen monitor read < 20 ppm.

[0090] The nonwoven samples were prepared as 7 in x 9 in (17.8 cm x 22.9 cm) pieces and placed individually into 8 in x 10 in (20 cm x 25 cm) seal-top plastic bags. The sample-containing bags were opened inside a glove box with nitrogen for inerting until the glove box oxygen monitor read < 20 ppm. The bags were then opened, removed from the glovebox and taped onto a PET carrier web being conveyed at 35 feet per minute (fpm) through an ElectroCure electron beam (Energy Sciences, Inc., Wilmington, MA). Samples were irradiated at 300 kV to a specified dose, typically 10 MRad. The resultant beam current was 55 mA.

[0091] After irradiation, the samples were removed and transferred back to the glove box. The oxygen monitor was allowed to reach < 20 ppm before the bags were opened. To deposit monomer and begin polymerization, the jar of aqueous reaction mixture was shaken by hand and then poured onto the nonwoven within the bag. To encourage wetting throughout the sample, a hand roller was rolled over the sealed bag containing nonwoven and aqueous reaction mixture. After 3 hr reaction, samples were taken from the glove box, exposed to atmosphere and placed into boiling deionized water for 1 hr to further saturate the reaction and remove residual monomer. After this, the derivatized nonwovens were dried on polyethylene-lined aluminum trays in an ambient environment overnight and then further dried in a 70°C oven for 12-16 hr before subsequent characterization and performance testing.

[0092] Sample Dimensional Change After Functionalization

[0093] Length and width of functionalized samples after boiling were measured and compared to the original sample size. Dimensional change is expressed as area change using the following equation: % area change ={ [(Length of boiled sample x width of boiled sample) / (length of original sample x width of original sample)] – 1} x 100

[0094] Basis Weight

[0095] A known sample size (for example a 5.25 in disk) was cut from the sample and weighed to provide the basis weight in grams per square meter (gsm).

[0096] Evaluation of Weight Gain

[0097] The amount of monomer polymerized onto the fibers was determined by gravimetric analysis using the following equation: % weight gain = [(final web weight – initial web weight) / initial web weight] x 100

[0098] Surface Area

[0099] The total surface area of non-derivatized [9 inch (22.9 cm) by 7 inch (17.8 cm)] nonwoven samples was calculated using the following equation: Specific Surface Area = 4 / (density of polymer x effective fiber diameter) Sample Surface Area = Specific Surface Area x weight of nonwoven

[0100] Metanil Yellow Dynamic Binding Capacity (MYDBC)

[0101] MYDBC was measured using a 47 mm holder loaded with functional media and stacked with a non-functional 0.2 μm membrane to improve flow uniformity. The value was determined by 5% breakthrough of a 160ppm metanil yellow solution dissolved in 140 mM NaCl and 50 mM phosphate salts. The breakthrough point was determined by turbidity measurement which is calibrated for turbidity of 8ppm metanil yellow solution. The flow rate was set at 930 LMH. The MYDBC value is then normalized by the weight of chemically-functionalized copolymer and reported as mg / g (weight of amount of metanil yellow bonded / weight of chemically-functionalized copolymer). The chemically- functionalized copolymer weight is calculated from functional media weight and weight gain.

[0102] Substrate Samples 1-9 (SE1-SE9)

[0103] Nylon BMF, nylon SB and PP SB, were prepared using the Method of Making Spun- bond (SB) Nonwoven and Melt Blown (BMF) Nonwoven as described above. Shown in Table 1 are the substrate characteristics including thickness, basis weight, solidity, pressure drop (delta P), effective fiber diameter (EFD), and average actual fiber diameter (AFD) as measured on the resulting nonwovens. Also reported in Table 1 is the basis weight equivalent to polypropylene which is calculated for the nylon samples by taking their basis weight and multiplying by density the density of polypropylene (0.91 g / cm3) and dividing by the density of nylon (1.15 g / cm3). This was done to show that, if accounting for density, all of the samples had a similar basis weight. Table 1 sample Resin Web Thickness Basis Basis Solidity Delta P EFD Avg. type (mil) weight weight (%) (mm (µm) AFD (gsm) equiv. water) (µm) to PP (gsm) SE1 Nylon BMF 45.5 128.0 101.3 10.0 10.3 7.9 NASE2 Nylon BMF 40.5 121.0 95.7 10.4 6.1 10.0 NA SE3 Nylon BMF 42.5 121.0 95.7 10.0 4.3 11.9 NA SE4 Nylon BMF 45.4 130.0 102.9 10.0 3.4 13.7 NA SE5 Nylon SB 42.6 122.0 96.5 9.7 5.0 10.7 8.1 SE6 Nylon SB 41.8 123.0 97.3 9.9 3.3 13.3 11 SE7 PP SB 40.2 100.5 100.5 10.8 9.8 8.1 6.1 SE8 PP SB 42.5 98.5 98.5 9.0 5.0 10.5 7.9 SE9 PP SB 42.3 99.7 99.7 10.2 2.8 15.0 11.5

[0104] Comparative Examples 1-4 (CE-1 to CE-4) and Examples 1-2 (EX-1 to EX-2)

[0105] Both SB and BMF type nylon substrate samples were derivatized following the EB Derivatization Procedure. The aqueous reaction mixture contained 5 wt% MAPTAC and 6 wt% NVP in water for functionalizing.

[0106] Shown in Table 2 is the weight of the sample before derivatization (initial), weight after derivatization (final) and the corresponding % weight gain, indicating how much monomer was polymerized into the nonwoven.

[0107] Also reported in Table 2 is the length and width of the derivatized sample after boiling for 1 hour in water and before drying. The percent area changed is determined by multiplying this length and width and comparing to the initial length and width of the nonwoven before derivatization. As the initial nonwoven was a 9 inch by 7 inch piece, some of the samples changed more than others in dimension. Also reported in Table 2 is the surface area for each nonwoven sample. Comparing the % area change by surface area, CE-1 to CE-4 had a dramatic drop in % area change as the surface area increased versus EX-1 and EX-2. Table 2 Sample Substrate Web Weight Weight % Length Width Area Surface type initial final Weight (in) (in) change area (g) (g) gain [cm] [cm] (%) (m2) CE-1 SE1 BMF 4.99 9.8 96.4 8.9 7.8 10.2 2.197 [22.6] [19.8] CE-2 SE2 BMF 4.57 9.5 107.9 11.8 9.8 83.6 1.590 [30.0] [24.9] CE-3 SE3 BMF 4.86 9.7 99.6 12.9 10.5 115.0 1.421 [32.8] [26.7] CE-4 SE4 BMF 5.18 9.6 85.3 13.4 10.5 123.3 1.315 [34.0] [26.7] EX-1 SE5 SB 4.94 10.0 102.4 9.5 7.3 10.1 1.303 [24.1] [18.4] EX-2 SE6 SB 4.89 10.3 110.6 9.6 7.5 14.3 1.279 [24.4] [19.0]

[0108] As observed in Table 2, the spun-bond nonwovens, EX-1 and EX-2, generally have better dimensional stability and a higher weight gain compared to the blown melt nonwovens, CE-1 to CE-4. Further, EX-1 and EX-2 had a higher % weight gain than CE-1, even though CE-1 has higher surface area due to its smaller fiber diameter.

[0109] Comparative Examples 5-8 (CE-5 to CE-8)

[0110] Nonwoven media comprising PP SB were derivatized following the EB Derivatization Procedure. The aqueous reaction mixture contained 5 wt% MAPTAC, 6 wt% NVP, and 2 wt% GMA in water for functionalizing. GMA was added to the formulation to improve surface wetting on the polypropylene.

[0111] CE-5 to CE-8 and EX-1 and EX-2 were evaluated and the results are shown in Table 3. Shown in Table 3 is the weight of the sample before derivatization (initial), weight after derivatization (final) and the corresponding % weight gain. Also reported in Table 3 is the surface area and the average MYDBC taken from 3 different samples. Comparing the binding capacity of metanil yellow (MYDBC) versus % weight gain for the samples in Table 3, shows that the nonwovens comprising nylon had more monomer derivatized into the nonwoven samples and that these samples have improved binding capacity of metanil yellow. Table 3 Sample Substrate Polymer Web Weight Weight % Surface Avg. MYDBC type initial final Weight area (mg / g) (g) (g) gain (m2) CE-5 SE1 Nylon BMF 4.99 9.8 96.4 2.197 427.7 ± 85.4 EX-1 SE5 Nylon SB 4.94 10.0 102.4 1.606 425.3±33.3 EX-2 SE6 Nylon SB 4.89 10.3 110.6 1.279 423.1± 9.2 CE-6 SE7 PP SB 4.17 4.4 5.5 2.263 365.1± 37.1 CE-7 SE8 PP SB 4.05 4.3 6.2 1.695 234.1± 18.2 CE-8 SE9 PP SB 4.07 4.3 5.7 1.193 254.9± 22.9

[0112] Examples 3-6 (EX-3 to EX-6)

[0113] Substrate SE6 was derivatized following the EB Derivatization Procedure using the Derivatization formulations disclosed in Table 4. Shown in Table 4 is the weight of the sample before derivatization (initial), weight after derivatization (final) and the corresponding % weight gain. Also reported in Table 4 is the length and width of the derivatized sample after boiling for 1 hour in water and before drying and the % change in area. The samples were also tested for MYDBC and the results are reported in Table 4.Table 4 Sample Hand Derivatization Weight Weight % Length Width Area Avg. sheet formulation initial final Weight (in) (in) change MYDBC weight (g) (g) gain [cm] [cm] (%) (mg / g) (g) EX-3 4.89 5% MAPTAC 4.89 10.3 110.6 9.6 7.5 14.3 423.1 6% NVP [24.4] [19.0] EX-4 4.96 10% MAPTAC 4.96 15.7 216.5 9.8 7.7 19.8 408.6 12% NVP [24.9] [19.6] EX-5 4.95 8.8% AETAC 4.95 16.3 229.3 9.9 7.9 24.1 379.9 12% NVP [25.1] [20.1] EX-6 4.86 9.4% MAETAC 4.86 16.2 233.3 9.9 7.8 22.6 459.8 12% NVP [25.1] [19.8]

[0114] As shown in Table 4, there is a consistent scalability in functionalizing the spun-bond nylon nonwoven as shown in EX-3 and EX-4, where the doubling of the monomers lead to a doubling of the % weight gain. All of the samples in Table 4 show good dimensional stability and a high binding for metanil yellow.

[0115] Foreseeable modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention. This invention should not be restricted to the embodiments that are set forth in this application for illustrative purposes. To the extent that there is any conflict or discrepancy between this specification as written and the disclosure in any document mentioned or incorporated by reference herein, this specification as written will prevail.

Claims

What is claimed is:

1. A chemically-functionalized nonwoven comprising: a spun-bond nonwoven comprising a plurality of homogeneous fibers, wherein the plurality of homogeneous fibers comprise nylon, and wherein at least a portion of the plurality of homogeneous fibers are chemically-functionalized with an aqueous reaction mixture comprising an aminoalkyl (meth)acryloyl monomer.

2. The chemically-functionalized nonwoven of claim 1, wherein the aqueous reaction mixture is substantially free of poly(alkylene oxide) monomer.

3. The chemically-functionalized nonwoven according to any one of the previous claims, wherein the nylon comprises Nylon 6; Nylon 6,6; Nylon 1,6; Nylon 11; Nylon 12; Nylon 4,6; Nylon 4; Nylon 1,4; Nylon 510; Nylon TMDT; or combinations thereof.

4. The chemically-functionalized nonwoven according to any one of the previous claims, wherein the aminoalkyl (meth)acryloyl monomers are amino (meth)acrylates or amino (meth)acrylamides of Formula I or quaternary ammonium salts thereof (I) wherein R1is hydrogen or methyl, preferably methyl; L is —O— or —NH—; and Y is an alkylene and R2is (i) independently hydrogen or alkyl or (ii) the two R2groups taken together with the nitrogen atom to which they are attached can form a heterocyclic group that is aromatic, partially unsaturated, or saturated, and optionally, wherein the heterocyclic group is fused to a second ring that is aromatic, partially unsaturated, or saturated.

5. The chemically-functionalized nonwoven according to any one of the previous claims, wherein the aqueous reaction mixture further comprises a hydrophilic monomer.

6. The chemically-functionalized nonwoven according to claim 5, wherein the hydrophilic monomer comprises at least one of the following monomers: 2-hydroxyethyl(meth)acrylate (HEMA), 2- ethoxyethyl methacrylate (2-EOEMA), 2-hydroxypropyl(meth)acrylate, 3- hydroxypropyl(meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, 4-hydroxybutyl(meth)acrylate, N-vinyl caprolactam, N-vinyl acetamide, N-vinyl pyrrolidone, acrylonitrile, tetrahydrofurfurylacrylate, acrylamide, mono- or di-N-alkyl substituted acrylamide, glycerol methacrylate, and combinations thereof.

7. The chemically-functionalized nonwoven according to any one of the previous claims, wherein the aqueous reaction mixture further comprises a (meth)acryloyl epoxide monomer.

8. The chemically-functionalized nonwoven according to claim 7, wherein the (meth)acryoloyl epoxide monomer comprises at least one of the following: glycidyl methacrylate, or glycidyl acrylate.

9. A nonwoven comprising the chemically-functionalized nonwoven according to any one of the previous claims.

10. A filtration media comprising the chemically-functionalized nonwoven according to any one of claims 1-8.

11. A method of making a chemically-functionalized nonwoven, the method comprising: (i) providing a spun-bond nonwoven wherein the spun-bond nonwoven comprises a plurality of homogeneous fibers, wherein the plurality of homogeneous fibers comprise nylon; and (ii) contacting the spun-bond nonwoven with an aqueous reaction mixture comprising: an aminoalkyl (meth)acryloyl monomer; optionally, a hydrophilic monomer; and optionally, a (meth)acryloyl epoxide monomer; and (iii) exposing the spun-bond nonwoven to radiation.

12. The method of claim 11, wherein the spun-bond nonwoven has an effective fiber diameter of at least 5 micrometers and at most 25 micrometers.

13. The method of any one of claims 11-12, wherein the spun-bond nonwoven has a basis weight of at least 50 grams per square meter and at most 250 grams per square meter.

14. The method of any one of claims 11-13, wherein a 9 in (22.9 cm) by 7 in (17.8 cm) piece of the spun-bond nonwoven has a surface area of at least 1 m2and at most 2 m2.

15. The method of any one of claims 11-14, the chemically-functionalized nonwoven has a weight gain of at least 100% and at most 350% compared to the spun-bond nonwoven.

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