COMPOSITIONS, AND ARTICLES

BACKGROUND

The general preparation of silver nanowires (10-200 aspect ratio) is known. See, for example, Angew. Chem. Int. Ed. 2009, 48, 60, Y. Xia, Y. Xiong, B. Lim, S. E. Skrabalak, which is hereby incorporated by reference in its entirety. Such preparations typically employ Fe ²⁺ or Cu ²⁺ ions to "catalyze" the wire formation over other morphologies. The controlled preparation of silver nanowires having desired lengths and widths, however, is not known. For example, the Fe ²⁺ produces a wide variety of lengths or thicknesses and the Cu ²⁺ produces wires that are too thick for many applications.

The metal ions used to catalyze wire formation are generally primarily reported to be provided as a metal halide salt, usually as a metal chloride, for example, FeCl ₂ or CuCl ₂ . See, for example, J. Jiu, K. Murai, D. Kim, K. Kim, K. Suganuma, Mat. Chem. & Phys., 2009, 114, 333, which refers to NaCl, CoCl ₂ , CuCl ₂ , NiCl ₂ and ZnCl ₂ ; Japanese patent application publication JP2009155674, which describes SnCl ₄ ; S. Nandikonda, "Microwave Assisted Synthesis of Silver Nanorods," M.S. Thesis, Auburn University, August 9, 2010, which refers to NaCl, KC1, MgCl ₂ , CaCl ₂ , MnCl ₂ , CuCl ₂ , and FeCl ₃ ;

S. Nandikonda and E. W. Davis, "Effects of Salt Selection on the Rapid Synthesis of Silver Nanowires," Abstract INOR-299, 240th ACS National Meeting, Boston, MA, August 22-27, 2010, which discloses NaCl, KC1, MgCl ₂ , CaCl ₂ , MnCl ₂ , CuCl ₂ , FeCl ₃ , Na ₂ S, and Nal; Chinese patent application publication

CN101934377, which discloses Mn ²⁺ ; Y. C. Lu, K. S. Chou, Nanotech., 2010, 21, 215707, which discloses Pd ²⁺ ; and Chinese patent application publication

CN 102029400, which discloses NaCl, MnCl ₂ , and Na ₂ S.

SUMMARY

At least some embodiments provide methods comprising providing at least one first composition comprising at least one first reducible metal ion, and reducing the at least one first reducible metal ion to at least one first metal nanowire in the presence of at least one second metal ion comprising at least one lanthanide element or actinide element.

In such methods, the at least one first reducible metal ion may, for example, comprise at least one coinage metal ion, or at least one ion of an IUPAC Group 11 element, such as, for example, at least one silver ion. In at least some embodiments, the at least one first composition comprises silver nitrate.

In such methods, the at least one second metal ion may, for example, comprise at least one thorium ion. In some cases, the at least one second metal ion may comprise thorium in its +4 oxidation state. Some such methods may further comprise providing at least one compound comprising the at least one second metal ion at least nitrate moiety. An exemplary compound is thorium (IV) nitrate tetrahydrate.

In such methods, the reduction of the first reducible metal ion may, in some cases, occur in the presence of either or both of at least one protecting agent or at least one polyol.

In such methods, the at least one first metal nanowire may, for example, comprise an average diameter between about 10 nm and about 500 nm. In some cases, such an average diameter may be less than about 40 nm.

In such methods, the at least one first metal nanowire may, for example, comprise an aspect ratio between about 50 and about 10,000.

Some embodiments provide products comprising the at least one first metal produced by such methods. In some cases, such products may comprise at least one metal nanowire.

Other embodiments provide articles comprising such products. Still other embodiments provide compositions comprising at least one metal nanowire and at least one lanthanide ion or actinide ion. In some cases, the at least one metal nanowire comprises at least one silver nanowire. Such a metal nanowire may, for example, comprise an average diameter between about 10 nm and about 500 nm. Or such a metal nanowire may, for example, comprise an aspect ratio between about 50 and about 10,000. Or such a metal nanowire may, for example, comprises an average diameter between about 10 nm and about 150 nm, and an aspect ratio between about 50 and about 10,000. Yet still other embodiments provide products comprising such metal nanowires or articles comprising such products. Non-limiting examples of such articles include electronic displays, touch screens, portable telephones, cellular telephones, computer displays, laptop computers, tablet computers, point- of-purchase kiosks, music players, televisions, electronic games, electronic book readers, transparent electrodes, solar cells, light emitting diodes, other electronic devices, medical imaging devices, medical imaging media, and the like.

These embodiments and other variations and modifications may be better understood from the brief description of figures, description, exemplary embodiments, examples, and claims that follow. Any embodiments provided are given only by way of illustrative example. Other desirable objectives and advantages inherently achieved may occur or become apparent to those skilled in the art. The invention is defined by the appended claims.

BRIEF DESCRIPTION OF FIGURES

FIG 1 shows an optical micrograph of the silver nanowire product of Example 1.

FIG 2 shows an optical micrograph of the silver nanowire product of Example 2.

FIG 3 shows an optical micrograph of the silver nanowire product of Example 3.

DESCRIPTION

All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference.

U.S. Application No. 13/289,513, filed November 4, 2011, entitled NANOWIRE PREPARATION METHODS, COMPOSITIONS, AND

ARTICLES, is hereby incorporated by reference in its entirety. U.S. Provisional Application No. 61/500,156, filed June 23, 2012, entitled NANOWIRE

PREPARATION METHODS, COMPOSITIONS, AND ARTICLES, is hereby incorporated by reference in its entirety. Reducible Metal Ions and Metal Products

Some embodiments provide methods comprising reducing at least one reducible metal ion to at least one metal. A reducible metal ion is a cation that is capable of being reduced to a metal under some set of reaction conditions. In such methods, the at least one first reducible metal ion may, for example, comprise at least one coinage metal ion. A coinage metal ion is an ion of one of the coinage metals, which include copper, silver, and gold. Or such a reducible metal ion may, for example, comprise at least one ion of an IUPAC Group 11 element. An exemplary reducible metal ion is a silver cation. Such reducible metal ions may, in some cases, be provided as salts. For example, silver cations might, for example, be provided as silver nitrate.

In such embodiments, the at least one metal is that metal to which the at least one reducible metal ion is capable of being reduced. For example, silver would be the metal to which a silver cation would be capable of being reduced.

Nanostructures, Nanostructures, and Nanowires

In some embodiments, the metal product formed by such methods is a nanostructure, such as, for example, a one-dimensional nano structure.

Nanostructures are structures having at least one "nanoscale" dimension less than 300 nm, and at least one other dimension being much larger than the nanoscale dimension, such as, for example, at least about 10 or at least about 100 or at least about 200 or at least about 1000 times larger. Examples of such nanostructures are nanorods, nanowires, nanotubes, nanopyramids, nanoprisms, nanoplates, and the like. "One-dimensional" nanostructures have one dimension that is much larger than the other two dimensions, such as, for example, at least about 10 or at least about 100 or at least about 200 or at least about 1000 times larger.

Such one-dimensional nanostructures may, in some cases, comprise nanowires. Nanowires are one-dimensional nanostructures in which the two short dimensions (the thickness dimensions) are less than 300 nm, preferably less than 100 nm, while the third dimension (the length dimension) is greater than 1 micron, preferably greater than 10 microns, and the aspect ratio (ratio of the length dimension to the larger of the two thickness dimensions) is greater than five. Nanowires are being employed as conductors in electronic devices or as elements in optical devices, among other possible uses. Silver nanowires are preferred in some such applications.

Such methods may be used to prepare nanostructures other than nanowires, such as, for example, nanocubes, nanorods, nanopyramids, nanotubes, and the like. Nanowires and other nanostructure products may be incorporated into articles, such as, for example, electronic displays, touch screens, portable telephones, cellular telephones, computer displays, laptop computers, tablet computers, point-of-purchase kiosks, music players, televisions, electronic games, electronic book readers, transparent electrodes, solar cells, light emitting diodes, other electronic devices, medical imaging devices, medical imaging media, and the like.

Preparation Methods

A common method of preparing nanostructures, such as, for example, nanowires, is the "polyol" process. Such a process is described in, for example, Angew. Chem. Int. Ed. 2009, 48, 60, Y. Xia, Y. Xiong, B. Lim, S. E. Skrabalak, which is hereby incorporated by reference in its entirety. Such processes typically reduce a metal cation, such as, for example, a silver cation, to the desired metal

nanostructure product, such as, for example, a silver nanowire. Such a reduction may be carried out in a reaction mixture that may, for example, comprise one or more polyols, such as, for example, ethylene glycol (EG), propylene glycol, butanediol, glycerol, sugars, carbohydrates, and the like; one or more protecting agents, such as, for example, polyvinylpyrrolidinone (also known as

polyvinylpyrrolidone or PVP), other polar polymers or copolymers, surfactants, acids, and the like; and one or more metal ions. These and other components may be used in such reaction mixtures, as is known in the art. The reduction may, for example, be carried out at one or more temperatures from about 90 °C to about 190 °C. Actinide Ions

In some embodiments, the reduction of the reducible metal ion occurs in the presence of at least one second metal ion comprising at least one actinide element. Such a reduction may, for example, occur in the presence of at least one actinide element in its +2, +3, or +4 oxidation state. An exemplary second metal ion is Th ⁴⁺ . Such an ion may, for example, be provided by such compounds as thorium (IV) nitrate tetrahydrate.

EXEMPLARY EMBODIMENTS

U.S. Provisional Application No. 61/500,156, filed June 23, 2012, entitled NANOWIRE PREPARATION METHODS, COMPOSITIONS, AND ARTICLES, which is hereby incorporated by reference in its entirety, disclosed the following 20 non-limiting exemplary embodiments.

A. A method comprising:

providing at least one first composition comprising at least one first reducible metal ion; and

reducing the at least one first reducible metal ion to at least one first metal in the presence of at least one second metal ion comprising at least one lanthanide element or actinide element.

B. The method according to embodiment A, wherein the at least one first reducible metal ion comprises at least one coinage metal ion.

C. The method according to embodiment A, wherein the at least one first reducible metal ion comprises at least one ion of an IUPAC Group 11 element.

D. The method according to embodiment A, wherein the at least one first reducible metal ion comprises at least one silver ion.

E. The method according to embodiment A, wherein the at least one composition comprises silver nitrate.

F. The method according to embodiment A, wherein the at least one second metal ion comprises at least one thorium ion.

G. The method according to embodiment A, wherein the at least one second metal ion comprises thorium in its +4 oxidation state.

H. The method according to embodiment A, wherein the reduction occurs in the presence of at least one protecting agent.

J. The method according to embodiment A, wherein the reduction occurs in the presence of at least one polyol.

K. A product comprising the at least one first metal produced by the method according to embodiment A.

L. The product according to embodiment K comprising at least one metal nanowire.

M. An article comprising the product according to embodiment K.

N. A composition comprising at least one metal nanowire, at least one chloride ion, and at least one ion of a lanthanide element or at least one ion of an actinide element.

P. The composition according to embodiment N, wherein the at least one metal nanowire comprises at least one silver nanowire.

Q. The composition according to embodiment N, wherein the at least one metal nanowire comprises an average diameter between about 10 nm and about 500 nm.

R. The composition according to embodiment N, wherein the at least one metal nanowire comprises an aspect ratio between about 50 and about 10,000. S. The composition according to embodiment N, wherein the at least one metal nanowire comprises an average diameter between about 10 nm and about 150 nm, and an aspect ratio between about 50 and about 10,000.

T. A product comprising the at least one metal nanowire of the composition of embodiment N.

U. An article comprising the at least one product according to embodiment T. V. The article according to embodiment U comprising at least one of an electronic display, a touch screen, a portable telephone, a cellular telephone, a computer display, a laptop computer, a tablet computer, a point-of-purchase kiosk, a music player, a television, an electronic game, an electronic book reader, a transparent electrode, a solar cell, a light emitting diode, an electronic device, a medical imaging device, or a medical imaging medium.

EXAMPLES

Example 1

A 500 mL reaction flask containing 280 mL ethylene glycol (EG), 17.8 mg of thorium (IV) nitrate tetrahydrate, and 5.3 g of 27 mM sodium chloride in EG was degassed overnight at room temperature using nitrogen that was

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introduced below the liquid surface through a TEFLON fluoropolymer tube. The tube was then retracted from the liquid to provide nitrogen blanketing of the reaction flask headspace at approximately 0.5 L/min, after which the flask was then heated to 145 °C. Stock solutions of 0.50 M AgN0 ₃ in EG and 0.84 M polyvinylpyrrolidinone (PVP, 55,000 weight- average molecular weight) in EG were also degassed with nitrogen for, then 20 mL syringes of each were prepared. The AgN0 ₃ and PVP solutions were then added at a constant rate over 25 min via

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a 12 gauge a TEFLON fluoropolymer syringe needle. The flask was then held at temperature for 120 min, after which it was allowed to cool down to ambient temperature.

Figure 1 shows an optical micrograph of the silver nanowire product, which had an average nanowire length of 28.2 + 10.4 μιη and an average nanowire diameter of 56.1 + 13.7 nm, based upon measurement of at least 100 wires.

Example 2

Into a 500 mL reaction flask was added 290 mL propylene glycol

(PG), and 4.4 g polyvinylpyrrolidinone (PVP, 55,000 weight-average molecular weight). The headspace of the flask was blanketed with nitrogen at approximately 0.5 L/min and was heated to 110 °C while being stirred. 12.0 mL of 1.0 M AgN0 ₃ in PG and 10.0 mL of 42 mM lithium chloride in PG were added to the flask, each at a constant rate of 0.5 L/min, with the addition of the lithium chloride solution being delayed until 4.0 min after initiating the AgN0 ₃ solution feed. Immediately after completing feeding the AgN0 ₃ solution, 12.0 mL of 11 mM thorium (IV) nitrate tetrahydrate in PG was added to the flask at a constant rate of 0.5 L/min. The flask was then held at temperature for 132 min, after which it was allowed to cool down to ambient temperature.

Figure 2 shows an optical micrograph of the silver nanowire product, which had an average nanowire length of 10.2 + 6.6 μιη and an average nanowire diameter of 36.8 + 6.0 nm, based upon measurement of at least

100 wires. Example 3

Into a 500 mL reaction flask was added 290 mL propylene glycol (PG), and 4.5 g polyvinylpyrrolidinone (PVP, 55,000 weight-average molecular weight). The headspace of the flask was blanketed with nitrogen at approximately 0.5 L/min and was heated to 110 °C while being stirred. 12.0 mL of 1.0 M AgN0 ₃ in PG and 10.0 mL of 42 mM lithium chloride in PG were added to the flask, each at a constant rate of 0.5 L/min, with the addition of the lithium chloride solution being delayed until 4.0 min after initiating the AgN0 ₃ solution feed. Immediately after completing feeding the AgN0 ₃ solution, 12.0 mL of solution of 1.0 M AgN0 and 11 mM thorium (IV) nitrate tetrahydrate in PG was added to the flask at a constant rate of 0.5 L/min. The flask was then held at temperature for 102 min, after which it was allowed to cool down to ambient temperature.

Figure 3 shows an optical micrograph of the silver nanowire product, which had an average nanowire length of 16.3 + 6.9 μιη and an average nanowire diameter of 35.9 + 6.2 nm, based upon measurement of at least

100 wires.