A University of Akron (Akron, OH) science team has spun metal oxide nanofibers into protective clothing able to absorb and decompose chemical warfare agents.
FIG. 22 is an SEM image of as-spun aluminum acetate/PVP nanofibers able to absorb nerve agents.
University of Akron Chemical Engineering, Microscale Physiochemical Engineering Center Professor George C. Chase led a team of inventors including Matthew Espe, Edward Evans, Rex Ramsier, Darrell Reneker, Richard Tuttle and Jennifer Rapp in spinning new metal oxide fibers and nanofibers. The electrospinning processes for making them, and uses in fabrics and batteries are described in detail in U.S. Patent Application 20100009267.
FIG. 10 is a photograph illustration of one technique for visualizing electrospinning dynamics for metal oxide nanofibers as developed by the Akron inventors. Electrospinning is a simple and low cost electrostatic self-assembly method capable of fabricating a large variety of nanofibers.
The Akron method of producing a metal oxide nanofiber with improved catalytic, conductive, surface or structural functionality include the steps of: (I) selecting and providing a least one metal oxide precursor and at least one polymer to at least one nanofiber producing device, (II) mixing the at least one metal oxide precursor, the at least one polymer and optionally a solvent, (III) electrospinning the resultant mixture to produce fibers containing the at least one metal oxide precursor and the at least one polymer, (IV) thermally treating the fibers to create the metal oxide nanofiber having improved functionalities, and (V) collecting the metal oxide nanofiber.
Such metal oxide nanofibers possess the ability to absorb and decompose chemical warfare agents and other toxic chemicals. These nanofibers can be incorporated into protective clothing and devices for breathing or in another example may be used in lithium-ion batteries.
The Akron team made titania, alumina, and/or magnesia fibers and nanofibers, and the nanofabrication techniques to make them. In one instance alpha-phase aluminum oxide is utilized as one material in nanofibers.
Many of the chemical warfare nerve agents developed since World War I are organophosphorus esters. These species are liquids under normal environmental conditions and are intended to be dispersed as aerosols in the battlefield.
Human exposure to these compounds initiates reactions involving acetylcholinesterase, irreversibly inhibiting control over the central nervous system. The g-agents GB (sarin), GD (soman) and GF have the structure (RO)PO(CH.sub.3)(F), where R varies from straight chain, to branched, to cyclic alkyl groups, respectively.
The much more toxic and chemically heterogeneous V-series agents (e.g. VX) contain a P--S linkage to isopropyl amino functional moieties. It is the defunctionalization of these nerve agents by halogen, ester or sulphur bond scission that renders them either much less toxic or non-toxic.
Alumina, titania, magnesia and other oxides can adsorb and in some cases decompose nerve agents and related compounds. The highest surface reactivity has been shown to occur on nano-scale crystalline particles having many edge and defect sites. Such materials, whose properties are dominated by large surface to volume ratios, exhibit reactive behavior used for the decomposition of nerve agents.
Alumina, titania, magnesia and other oxides can adsorb and in some cases decompose nerve agents and related compounds. The highest surface reactivity has been shown to occur on nano-scale crystalline particles having many edge and defect sites. Such materials, whose properties are dominated by large surface to volume ratios, exhibit reactive behavior used for the decomposition of nerve agents.
FIG. 18 shows SEM images of titania nanofibers doped with erbia particles for decomposing nerve agents.
It is difficult to incorporate nanoparticles into structures such as clothing or filters intended for field service, since methods to encapsulate or constrain them must not lead to decreased surface area or reactive behavior. It is critical to use materials that exhibit nanoscale surface structure for phosph(on)ate decomposition. These materials are in the form of nanofibers with macroscopic lengths for incorporation into clothing and filters.
Metal oxide nanoparticles are known to decompose nerve agents, but they cannot be incorporated into clothing and breathing filters. Nanofibers can be incorporated into clothing and used in respiratory filters while still exhibiting the nano-scale surface reactivity necessary for nerve agent detoxification. The Akron team believes they have overcome this problem.
Metal oxide nanoparticles are known to decompose nerve agents, but they cannot be incorporated into clothing and breathing filters. Nanofibers can be incorporated into clothing and used in respiratory filters while still exhibiting the nano-scale surface reactivity necessary for nerve agent detoxification. The Akron team believes they have overcome this problem.
According to the inventors, the large surface area of these nanofibers creates a high surface reactivity while the length of nanofibers make them suitable for incorporation into protective clothing and devices for breathing. Properties of the nanofiber materials such as strength, porosity, capacity to absorb chemical species, etc., can be controlled by combining different fibers into a composite. The composites are ideal for protective breathing apparatus and clothing to permit moisture exchange and alleviate thermal stress on the wearer.
FIG. 12 is a photo detailing microscopic evidence of the influence of nanofibers on droplet capture by filtration media.
Secondary cell batteries (nickel-cadmium, nickel/metal-hydride and lithium-ion rechargeable batteries account for nearly 10% of the global battery market. Rechargeable lithium ion batteries make up a significant amount of that market with growth increasing on an annual basis. This growth in rechargeable and secondary cell batteries is driven by increasing sales in portable devices such as cell phones and laptop computers.
FIG. 40 is a drawing of the design of a Li ion battery, where the separator/electrolyte is fabricated from alumina/LiX nanofibers
There is a need in the art for a suitable material which can be incorporated as a nanofiber and used in clothing and/or breathing filters for the protection against chemical agents. There is also a need in the art for a suitable material for use in batteries. The use of metal oxide nanofibers offers a means of providing such a suitable material.
The recent synthesis of titania nanofibers and those modified with erbia are described. This work demonstrates the ability to form metal oxide nanofibers and modify them as required. The production of alumina and magnesia nanofibers for nerve agent detoxification follows the same processing steps and chemistry described below, applied to additional metal oxide precursors. The incorporation of metal oxide particles into a metal oxide nanofiber matrix is also demonstrated. This indicates that one can include metal oxide particles into nanofibers of other oxides or polymers. This leads to unique fabrics and filters for personal protection from nerve agents.
