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Patent Issued for Polymeric Composites Having Oriented Nanomaterials and Methods of Making the Same

June 25, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventors Elimelech, Menachem (New Haven, CT); Osuji, Chinedum (Norwalk, CT); Mauter, Meagan (Pittsburgh, PA), filed on October 11, 2012, was published online on June 10, 2014.

The assignee for this patent, patent number 8748504, is Yale University (New Haven, CT).

Reporters obtained the following quote from the background information supplied by the inventors: "Many properties of polymer nanocomposites are determined by the anisoptropy and orientation of the sequestered nanomaterials. In some cases, the anisotropy of the nanomaterial is useful only for the realization of an isotropic system property. For example, the bulk mechanical properties of polymer melts may be enhanced by the inclusion of high-aspect ratio nanoparticles, which have a lower percolation threshold than an equivalent mass of spherical nanoparticles (Pike et al., 1974, Physical Review B 10:1421-1434). In other cases, the anisotropy of the sequestered nanomaterial imparts 'higher level' anisotropy in the bulk properties of the system. Controlled orientation of nanomaterial inclusions in polymer films produced demonstrations of anisotropic permeability (Pike et al., 1974, Physical Review B 10:1421-1434; Holt et al., 2006, Science 2006, 312:1034-1037) thermal (Choi, et al., 2003, J. Appl. Phys. 94:6034-6039; Moniruzzaman et al., 2006, Macromolecules 39:5194-5205) and electrical (Du, et al. 2005, Physical Review B 72:121404-4; Sandler et al., 2003, Polymer 44:5893-5899) conductivity, enhanced mechanical properties (Haggenmueller et al., 2000, Chemical Physics Letters 330:219-225; Thostenson and Chou, 2002, J. Phys. D-Appl. Phys. 35:L77-L80), and photovoltaic activity (Ahir et al., 2008, Polymer 49:3841-3854; Kang et al., 2006, Solar Energy Materials and Cells 90:166-174).

"Current methods for controlling orientation in nanocomposite materials, however, are limited by their effectiveness and scalability. For example, for polymeric materials containing single-walled carbon nanotubes (SWNTs), mechanical shear (Jin et al., 1998, Appl. Phys. Lett. 73:1197-1199), anisotropic flow (Haggenmueller et al., 2000, Chemical Physics Letters 330:219-225; Kim et al., 2007, Nano Lett. 7:2806-2811), gel extrusion (Vigolo et al., 2000, Science 290:1331-1334), melt stretching (Fagan et al., 2007 Phys. Rev. Lett. 98:147402), magnetic fields (Lagerwall et al., 2007, Advanced Materials 19:359-364; Walters et al., 2001, Chemical Physics Letters 338:14-20), and electric fields (Park et al., 2006, Journal of Polymer Science Part B: Polymer Physics 44:1751-1762) have been used to varying effect to induce nanotube alignment. Despite these efforts, the fabrication of aligned SWNT-polymer nanocomposite matrices remains difficult, particularly in thin-film geometries where vertical alignment of the SWNTs in polymer films is attractive for applications in size and chemo-selective transport (Majumder et al., 2005, J Am Chem Soc. 127:9062-9070; Lopez-Lorente et al., 2010, Anal Chem. 82(13):5399-407). Thus, a need exists for systems and methods of aligning nanomaterials within mesophases and polymerized nanocomposites. The present invention fulfills these needs."

In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "The present invention relates to the development and fabrication of thin-film polymer nanocomposites containing vertically aligned nanomaterials, such as single-walled carbon nanotubes (SWNTs). In certain embodiments, the present invention utilizes liquid crystal mesophases of hexagonally packed cylindrical micelles that orient with their long axes parallel to an applied magnetic field, thereby directing the alignment of the nanomaterials, such as SWNTs, sequestered in the micellar cores. In certain embodiments, the mesophase may be a stable, single-phase material containing monomers that can be polymerized after nanotube alignment to form the nanocomposite polymer.

"Accordingly, the present invention relates to a method of aligning a nanomaterial in a polymeric film. The method includes the steps of adding at least one nanomaterial into a mesophase comprising at least one surfactant and at least one monomer, applying a magnetic field to the mesophase, wherein the at least one surfactant and nanomaterial at least partially align in response to the magnetic field, and polymerizing the mesophase to form a film containing the at least partially aligned surfactant and nanomaterial.

"In one embodiment, the mesophase includes a crosslinker. In another embodiment, the mesophase includes a photoinitiator. In another embodiment, the monomer is polymerized by exposing the mesophase to UV light. In another embodiment, the at least one surfactant is dodecyltrimethylammonium bromide (DTAB). In another embodiment, the at least one monomer is hydroxyethylmethacrylate (HEMA). In another embodiment, the nanomaterial is a single walled carbon nanotube. In another embodiment, the crosslinker is poly(ethylene glycol)-400 dimethacrylate. In another embodiment, the photoinitiator is Darocur TPO. In another embodiment, the method also includes the steps of raising the temperature of the mesophase such that the at least one surfactant is in a disordered state prior to applying the magnetic field to the mesophase, and controlling the rate of cooling of the mesophase as the surfactant returns to an ordered state while the magnetic field is applied. In another embodiment, the nanomaterial is mixed in a solution comprising a dispersing agent prior to adding the nanomaterial to the mesophase. In another embodiment, the dispersing agent is sodium taurodeoxycholate (TDOC). In another embodiment, the present invention includes a polymeric film formed by the method described herein. In another embodiment, the amount of DTAB in the mesophase is between 30-60%. In another embodiment, the amount of HEMA in the mesophase is between 10-30%. In another embodiment, the at least partial alignment of the at least one surfactant and nanomaterial is directed by a magnetic field strength of less than 6 Tesla (T).

"The present invention also relates to a nanocomposite that includes at least one nanomaterial, at least one surfactant, at least one monomer, at least one crosslinker, and at least one photoinitiator, wherein the at least one nanomaterial and surfactant are at least partially aligned via exposure to a magnetic field, and wherein the at least one monomer is polymerized via exposure to UV light after the at least one nanomaterial and surfactant are at least partially aligned. In one embodiment, the at least one nanomaterial is a single walled carbon nanotube, the at least one surfactant is dodecyltrimethylammonium bromide (DTAB), the at least one monomer is hydroxyethylmethacrylate (HEMA), the at least one crosslinker is poly(ethylene glycol)-400 dimethacrylate, and the at least one photoinitiator is Darocur TPO.

"The present invention also relates to a method of fabricating a nanocomposite. The method includes the steps of adding at least one nanomaterial into a mesophase comprising dodecyltrimethylammonium bromide (DTAB), hydroxyethylmethacrylate (HEMA), poly(ethylene glycol)-400 dimethacrylate and Darocur TPO, raising the temperature of the mesophase such that the mesophase is in a disordered state, applying a magnetic field having a strength of less than 6 Tesla to the mesophase, wherein the DTAB at least partially aligns in response to the magnetic field, controlling the rate of cooling of the mesophase as it returns to an ordered state, and polymerizing the mesophase to form a polymeric film containing the at least one nanomaterial. In one embodiment, the at least one nanomaterial is a single walled carbon nanotube."

For more information, see this patent: Elimelech, Menachem; Osuji, Chinedum; Mauter, Meagan. Polymeric Composites Having Oriented Nanomaterials and Methods of Making the Same. U.S. Patent Number 8748504, filed October 11, 2012, and published online on June 10, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8748504.PN.&OS=PN/8748504RS=PN/8748504

Keywords for this news article include: Nanoparticle, Nanotechnology, Yale University, Chemical Physics, Emerging Technologies, Single Walled Carbon Nanotubes.

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Source: Journal of Engineering


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