Abstract:
Some embodiments of the invention include an article of manufacture that is self-sealing, and a method of preparing the article of manufacture. The article of manufacture includes at one or more base layers with a plurality of overlapping strands, and at least one polymer coating layer at least partially covering at least some portions of at least some strands of at least a portion of the base layer. The polymer coating layer can swell by absorbing at least one target substance. A plurality of voids is distributed between at least some of the overlapping strands, where upon swelling by a target substance, at least some of the voids reversibly reduce in size or partially close, or completely seal.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 62/331,883 filed on May 4, 2016, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    When sent into an area with a high risk of exposure to chemical weapon agents (“CWA”), troops are deployed in mission oriented protective posture (“MOPP”) gear, and are required to remain in the gear until either the threat passes or they leave the high risk area. The goal of MOPP apparel is to prevent transport of chemical and biological agents. Currently this is achieved using MOPP apparel that includes pore-less polymeric coatings. However, in addition to being impermeable to harmful species, the coating is a barrier for moisture transport. As a result, evaporative cooling through sweating, along with conductive, convective, and radiative cooling is significantly diminished, or completely prevented. This places a significant thermal load on the soldier, and limits the safe use of MOPP gear to about 1 hour in a moderate climate. This time limit is even further decreased in regions such as the Middle-East that can experience significant solar loads and ambient temperatures above 130° F. Consequently, to enable working in MOPP gear for any extended period of time, additional special garments must be worn, including garments with cooling provided by phase change materials (e.g. ice) or using active fluid pumping. Although effective, the addition of a cooling system increases the size, weight, complexity, and cost of the MOPP gear. Furthermore, additional requirements for operation may not always be available in the field, such as batteries or other power sources to run pumps or refrigeration units to pre-freeze the phase change material. In addition, highly specialized cooled MOPP gear may not be readily available in case of a surprise attack, for example, such as in the case of the recent Sarin attack in Syria. Further, in addition to the problems posed by thermal issues, many materials currently utilized in MOPP gear can absorb varying amounts of some CWA, which has the potential to cause a range of serious problems with their use in the field, including, for example, post-exposure CWA release outside of a high risk zone. The majority of CWA substances are low vapor pressure and surface tension liquids with extreme toxicity that are spread in aerosol form. Consequently, to rapidly form an effective barrier, the barrier materials must seal upon contact with a few micro-droplets of the liquid. 
       SUMMARY 
       [0003]    Some embodiments include an article of manufacture comprising at least one base layer comprising a plurality of overlapping strands, and at least one polymer coating layer at least partially covering at least some portions of at least some strands of at least a portion of the at least one base layer. In some embodiments, the at least one polymer coating layer is configured and arranged to swell by at least partially absorbing at least one target substance. Some embodiments include a plurality of voids distributed between at least some of the overlapping strands, where upon swelling by the at least one target substance, at least some of the voids can reversibly reduce in size or partially close, or completely seal. 
         [0004]    In some embodiments of the invention, at least a portion of the at least one base layer includes a weave, knit, mesh, mesh-like material, and/or netting. In some embodiments, the at polymer coating layer comprises Poly-N-alkyl-N-phenylacrylamide polymer with a monomer sub-unit of: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0005]    wherein the alkyl group has between 1 and 18 carbon atoms. 
         [0006]    In some embodiments, the polymer coating layer comprises Poly-N-phenylacrylamide polymer with a monomer sub-unit of: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0007]    In some further embodiments, the polymer coating layer comprises Poly-3,5-bis(ethoxy(ethoxymethyl))phenyl acrylate. 
         [0008]    In other embodiments, the polymer coating layer comprises a phenyl acrylate polymer of: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0009]    wherein n=0-18. 
         [0010]    In some further embodiments, the polymer coating layer comprises polymer microspheres. In some embodiments, the polymer microspheres are spray-coated, polymer microspheres, dip-coated polymer microspheres, and water-fall coated polymer microspheres. In some further embodiments, the polymer microspheres comprise an elastomer polymer. In other embodiments, the polymer microspheres comprise a core-shell polymer microsphere. 
         [0011]    In some embodiments, the polymer coating layer includes a reactive monomer. In some further embodiments, the reactive monomer is crosslinkable within the polymer layer. 
         [0012]    In some embodiments, the strands include a polymer selected from polyester, polypropylene, polyethylene, nylon, rayon, acrylic, polyurethane, Teflon®, ethylene-vinyl acetate copolymer, aramid-based polymer, sodium acrylate polymer, polydimethylsiloxane. In other embodiments, the strands include a natural or naturally-derived materials selected from cotton, wool, silk, cellulosic viscose, cellulosic acetate, cupro, and linen. In some embodiments, the target substance is a chemical warfare agent. 
         [0013]    Some embodiments include a method of preparing a self-sealing material or surface comprising providing at least one base layer comprising a plurality of overlapping strands and a plurality of voids distributed between at least some of the overlapping strands. In some embodiments, the method includes applying one or more polymer coating layers to the at least one base layer so that at least some of the polymer coating layer at least partially covers at least some portions of at least some strands of at least a portion of the at least one base layer. In some embodiments of the method, the polymer coating layer is swellable by at least partially absorbing at least one target substance, where at least some of the voids reduce in size or partially close, or completely seal. 
         [0014]    In some embodiments of the method, the polymer coating layer comprises Poly-N-alkyl-N-phenylacrylamide polymer with a monomer sub-unit of: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0015]    wherein the alkyl group has between 1 and 18 carbon atoms. 
         [0016]    In some embodiments, the polymer includes a solid or bulk polymer, polymer microspheres, and/or monomer. 
         [0017]    In some embodiments, the polymer coating layer comprises Poly-N-phenylacrylamide polymer with a monomer sub-unit of: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0018]    In some further embodiments of the method, the polymer coating layer comprises a phenyl acrylate polymer of: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0019]    wherein n=0-18. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  shows a schematic illustration of an open-pore breathable fabric before and after exposure to chemical weapon (CW) agents in accordance with some embodiments of the invention. 
           [0021]      FIG. 2  shows images of PDMS polymer before and after exposure to silicone oil in accordance with some embodiments of the invention. 
           [0022]      FIG. 3  illustrates results showing self-sealing fabric capability made of fibers/mesh coated with an absorbent polymer in accordance with some embodiments of the invention. 
           [0023]      FIG. 4  shows a schematic of alternative self-sealing fabric achieved with absorbing polymeric microspheres in accordance with some embodiments of the invention. 
           [0024]      FIG. 5  is shows images of nylon fabric covered in a plurality of example superabsorbent polymer (sodium polyacrylate) particles before exposure to water. 
           [0025]      FIG. 6  shows the nylon fabric polymer with polymer (sodium polyacrylate) particles of  FIG. 5  after exposure to water. 
           [0026]      FIGS. 7 and 8  show chemical structures of target monomers for the preparation of selectively absorbent polymer coatings in accordance with some embodiments of the invention. 
           [0027]      FIG. 9  shows a schematic of relevant transport and chemo-mechanical processes involved in micro-drop impact onto absorbing elastomer fibers or spheres in accordance with some embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
         [0029]    The following discussion is presented to enable a person skilled in the art to make and use embodiments of the invention. Various modifications to the illustrated embodiments will be readily apparent to those skilled in the art, and the generic principles herein can be applied to other embodiments and applications without departing from embodiments of the invention. Thus, embodiments of the invention are not intended to be limited to embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of embodiments of the invention. Skilled artisans will recognize the examples provided herein have many useful alternatives that fall within the scope of embodiments of the invention. 
         [0030]    Some embodiments include smart self-decontaminating and breathable fabric that self-seals into an impermeable barrier in response to contact with one or more target substances such as a wide range of CWA agents. In normal conditions, the proposed smart fabric would be breathable and could be deployed as part of regular gear, minimizing the need for specialized protective gear and related equipment. Some embodiments of the invention include smart self-decontaminating and breathable fabric that can self-seal into an impermeable barrier in response to contact to conventional CWA materials. Some embodiments include materials formed into a fabric material with open pores that, in the absence of the presence of CWA materials, can enable or allow moisture transport through the fabric from one side to an opposite side. In some embodiments, upon contact with CWA materials (e.g., such as CWA in the form of micro-droplets), fabrics that include one or more coatings of one or more absorbing polymers disclosed herein (e.g., such as elastomers) can rapidly seal due to physical swelling of the polymer. Further, some embodiments include materials that can degrade absorbed CWA materials. For example, some embodiments include the addition of a carbon-based material (e.g., such as AZTM-TEDA available from Calgon Carbon Corporation, 500 Calgon Carbon Drive, Pittsburgh, Pa.) or similar material that is mixed with the absorbing polymers. 
         [0031]    In some embodiments of the invention, the materials useful for forming or creating self-sealing and self-decontaminating materials, structures, layers, articles or goods can include at least one type of fabric or fabric-forming material, at least one textile or textile-forming material, and/or at least one yarn or yarn-forming material. In some embodiments of the invention, the materials useful for fabricating self-sealing and self-decontaminating materials can include woven and/or knitted materials. In some embodiments, any portion of the materials can comprise a plurality of overlapping strands such as fibers, threads, wires, whiskers, and/or filaments (or any combination thereof) that can be assembled as a weave, knit, mesh, mesh-like material, and/or netting. In some embodiments, the materials that can be formed into a single layer of weave, knit, mesh, and or netting. In some embodiments, a multi-layer garment can be used allowing the development of a multifunctional protective system. For example, some further embodiments include double-layer weave, knit, mesh, and or netting. Other embodiments include more than two layers of weave, knit, mesh, and or netting. In some further embodiments, the materials useful for self-sealing and self-decontaminating materials can include an expanded weave, knit, mesh, and or netting that includes a structure that is three-dimensional (e.g., similar to a sponge or sponge-like structure). 
         [0032]    In some further embodiments of the invention, the materials useful for self-sealing and self-decontaminating materials include non-woven portions. For example, in some embodiments, at least a portion of the materials can comprise woven or knitted fibers, threads, wires, strands, whiskers, and/or filaments that are assembled as a weave, knit, mesh, and or netting. In other embodiments, the materials can be completely non-woven (i.e., can be substantially devoid of knitted or woven portions). 
         [0033]    Some embodiments can include materials that comprise woven or knitted fibers, threads, wires, strands, whiskers, and/or filaments that can be assembled as a weave, knit, mesh, and/or netting coated before they are woven or knitted. In some other embodiments, the materials can comprise woven or knitted fibers, threads, wires, strands, whiskers, and/or filaments that are assembled as a weave, knit, mesh, and or netting and then at least partially coated with an active layer, film or material, including, but not limited to a polymer, copolymer, polymer-blend, that is configured to absorb a target substance such as one or more CWA materials. In some embodiments, the active layer, film or material can comprise an elastomer. In other embodiments, the active layer, film or material can comprise a non-elastomer. 
         [0034]    In some embodiments of the invention, the materials useful for self-sealing and self-decontaminating materials include at least one synthetic material and/or at least one non-synthetic material. For example, some embodiments can include naturally-derived materials including, but not limited to, cotton, wool, silk, cellulosic (viscose, acetate, cupro), and linen. In some other embodiments, the materials useful for self-sealing and self-decontaminating materials include at least one synthetic material including, but not limited to, any polymer, copolymer and/or polymer-blend of polyester, polypropylene, polyethylene, nylon, rayon, acrylic, polyurethane, Teflon®, ethylene-vinyl acetate copolymer, or a combination thereof. Some further embodiments include aramids, including, but not limited to KEVLAR® materials. KEVLAR is a registered trademark of E.I. DuPont de Nemours &amp; Company. Teflon® is a registered trademark of DuPont. 
         [0035]    Referring to  FIG. 1  material transformation schematic  100 , some embodiments include an open-pore fabric material  110  comprising a matrix of fibers  130  with voids or pores  140  formed between the fibers  130 . In some embodiments, the fibers  130  can be coated with a coating  135  (see inset la) which has a high absorption capacity for a broad range chemical liquids including CWA&#39;s. In some embodiments, when exposed to one or more CWA materials, the coating  135  can swell, which in turn can cause the size of the pores  140  to decrease (shown as self-sealed impermeable fabric  120 ). In some embodiments, the open-pore fabric material  100  can comprise any of the materials or combinations of materials described earlier. Further, in some embodiments, the coating  135  can comprise any of the active layer, film or materials described earlier. In some embodiments, the number, spacing, and thickness of fibers  130 , and/or size of the pores  140  can vary from that illustrated in  FIG. 1 . For example, in some embodiments, the size of the pores  140  can be smaller than that represented in  FIG. 1  due to thicker fibers  130 , closer spacing of fibers  130 , and/or the thickness of the coating  135 . The self-sealed impermeable fabric  120  shows matrix of fibers  150  with the coating  155  extending throughout the fabric  120 , and represents open-pore fabric material  110  after CWA exposure. 
         [0036]      FIG. 2  shows images of polydimethylsiloxane (“PDMS”) polymer before (image  210 ) and after (image  250 ) exposure to silicone oil in accordance with some embodiments of the invention. In this non-limiting example embodiment, in the image  210 , voids  225 ,  235  are shown (generally corresponding to pores  140  shown in  FIG. 1 ). Following swelling in silicone oil, the non-limiting embodiments in image  250  shows the closed ports  255 ,  265 , corresponding to voids  225 , 235 . In some embodiments, the closure is reversible (e.g. when at least some of the silicone oil is extracted or migrates from the polymer). 
         [0037]      FIG. 3  illustrates a plot  300  with results showing self-sealing fabric capability made of fibers/mesh coated with an absorbent polymer in accordance with some embodiments of the invention. The results for  FIGS. 2 and 3  illustrate that with proper sizing, the pores can be completely sealed in response to swelling (e.g. in some embodiments, the original pore diameter is below about 20 μm for the illustrative example of PDMS swelling with 10 cSt viscosity silicone oil). In some embodiments, while the volume of PDMS roughly doubles upon exposure to the utilized silicone oil, some active layers or coatings can have a higher swelling ratio when exposed to CWA&#39;s and other specific substances. 
         [0038]    In some embodiments of the invention, the active layer or coating can comprise microspheres of the absorbing polymers. For example,  FIG. 4  shows a schematic  400  of alternative self-sealing fabric  410  achieved with absorbing polymeric microspheres  440  (shown generally positioned around or over the intersection of two fibers  425  at the corner of pores  430 ). The schematic  400  illustrates that upon swelling with CWA, a distribution of microspheres can create a barrier coating (shown as  445  on the fabric  420 ). In some embodiments, microspheres  440  can be easily and rapidly applied to various materials using simple techniques such as spray-coating, dip-coating, water-fall coating, or other conventional coating process. In some embodiments, individual fibers  425  can be coated with an elastomeric polymer using dip-coating. Some embodiments include controlled post polymerization cross-linking that can be performed at or near room temperature through the introduction of a reactive monomer into the polymer structure, followed by reaction with a cross-linking agent. In other embodiments, emulsion polymerization can be used to synthesize microspheres of the elastomer or core-shell microspheres including secondary material for CWA degradation. In some embodiments, these materials can be applied to different fabrics using spray-coating with an adhesive. In some embodiments, microspheres can be sprayed with an elastic adhesive that can result in formation of a composite (e.g., not only with decontamination particles, but comprising an adhesive-super absorbing polymer (“SAP”) microsphere composite. 
         [0039]      FIG. 5  shows images  500  of nylon fabric polymer (shown as fibers  525  and pores  530  in the magnified image  520  of image  510 ) covered in example super-absorbing polymer (sodium polyacrylate) particles  535  before exposure to water. Further, images  600 , with inset  625  (shown at higher magnification in image  650 ) of  FIG. 6  shows the nylon fabric polymer with polymer (e.g., sodium polyacrylate) particles of  FIG. 5  after exposure to water. It has been observed that, in some cases, the particles of sodium polyacrylate can absorb a quantity of water that is equal to several hundred times its own weight). Active layers or coatings of particles of sodium polyacrylate can be combined with materials that absorb chemical vapors and chemically degrade them to non-toxic products. For example, some products can be synthesized by mixing powdered AZTM-TEDA carbon and the coating precursor prior to polymerization/cross-linking. Upon polymerization, the particles can be locked into the polymer matrix. 
         [0040]    Some embodiments include polymers that can swell to several times their dry weight on exposure to one or more CWA&#39;s. Some embodiments include polymers prepared from the monomers  700 ,  800  shown in  FIGS. 7 and 8 . For example, referring to  FIG. 7 , some embodiments include the use of N-butyl-N-phenylacrylamide. Further, other embodiments can include N-butyl-N-phenylacrylamide related compounds including different lengths of the alkyl group on the nitrogen (e.g., from 0 to 18 carbon atoms), and/or various substitution on the phenyl ring (e.g., such as methyl, ethyl, halogen, ether, etc.), and/or larger aromatic ring groups (e.g., naphthyl, anthracenyl, etc.) Referring to  FIG. 8 , some embodiments include the use of 3,5-bis(ethoxy(ethoxymethyl))phenyl acrylate, with n=2 related compounds and including different values of n (e.g., with n being 0-18), as well as propylene oxide oligomers with the same n values. In some embodiments, the monomers can produce materials that are 1) non-swelling on exposure to water, 2) have a many degrees of freedom in regards to internal bond rotation to enhance dissolution of the side chains and provide a low barrier to backbone rearrangement on swelling, 3) have a branched side chain structure to minimize interaction between polymer strands, and 4) have polarizable aromatic moieties built into the structure to increase Van der Waals interaction of the side chains with the target liquids. 
         [0041]      FIG. 9  illustrates that with limited quantity of the swelling liquid, micro-drop impact and surface spreading, liquid diffusion, and localized swelling can induce non-trivial anisotropic change of the absorbing polymer (such as any of the coated fiber or microsphere structures described herein). Furthermore, the dynamics of these processes is important, where the rapid seal formation of these materials is critical to preventing user exposure to CWA substances. For example, with polymer materials shown as  915 ,  910 , with exposure to agent  905 , the agent can impact can spread and diffuse into the polymer causing swelling, shape change and pore sealing (represented as area  920 ). 
         [0042]    It will be appreciated by those skilled in the art that while the invention has been described above in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. Various features and advantages of the invention are set forth in the following claims.