U.S. patent application number 14/043966 was filed with the patent office on 2014-05-08 for nanowire preparation methods, compositions, and articles.
The applicant listed for this patent is Carestream Health, Inc.. Invention is credited to Jeffrey Blinn, Doreen C. Lynch, William D. Ramsden, Junping Zhang.
Application Number | 20140123808 14/043966 |
Document ID | / |
Family ID | 50621145 |
Filed Date | 2014-05-08 |
United States Patent
Application |
20140123808 |
Kind Code |
A1 |
Lynch; Doreen C. ; et
al. |
May 8, 2014 |
NANOWIRE PREPARATION METHODS, COMPOSITIONS, AND ARTICLES
Abstract
Methods of preparing nanowires by reducing metal cations are
disclosed and claimed, where the metal cation reduction occurs in
at least two stages. Such methods can exhibit improved
reproducibility and reduced variability. The product nanowires are
useful in, for example, electronics applications.
Inventors: |
Lynch; Doreen C.; (Afton,
MN) ; Ramsden; William D.; (Afton, MN) ;
Blinn; Jeffrey; (Maplewood, MN) ; Zhang; Junping;
(Saint Paul, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Carestream Health, Inc. |
Rochester |
NY |
US |
|
|
Family ID: |
50621145 |
Appl. No.: |
14/043966 |
Filed: |
October 2, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61723942 |
Nov 8, 2012 |
|
|
|
Current U.S.
Class: |
75/343 |
Current CPC
Class: |
C22C 5/06 20130101; B22F
1/0025 20130101; B22F 9/24 20130101; B82Y 30/00 20130101; B22F
2001/0037 20130101 |
Class at
Publication: |
75/343 |
International
Class: |
B22F 9/18 20060101
B22F009/18 |
Claims
1. A method comprising: providing at least one first composition
comprising 1,2-propylene glycol, polyvinyl pyrrolidone, and
ammonium chloride; adding at least one second composition to the at
least one first composition, the adding occurring over the course
of at least about 16 hrs, and the at least one second composition
comprising 1,2-propylene glycol and silver nitrate; and reducing at
least a portion of the silver nitrate to silver nanowires.
2. The method according to claim 1, further comprising heating the
at least one first composition to a temperature less than about
140.degree. C.
3. The method according to claim 1, further comprising heating the
at least one first composition to a temperature between about
80.degree. C. and about 120.degree. C.
4. The method according to claim 1, further comprising heating the
at least one first composition to a temperature of about 90.degree.
C.
5. The method according to claim 1, wherein the at least one first
composition further comprises silver nitrate.
6. The method according to claim 5, wherein providing the at least
one first composition comprises: providing at least one third
composition comprising silver nitrate; and adding at least one
fourth composition to the at least one third composition, the at
least one fourth composition comprising ammonium chloride.
7. The method according to claim 5, wherein providing the at least
one first composition comprises: providing at least one third
composition comprising polyvinyl pyrrolidone; forming at least one
fourth composition by adding at least one fifth composition to the
at least one third composition, the at least one fifth composition
comprising silver nitrate; and adding at least one sixth
composition to the at least one fourth composition, the at least
one sixth composition comprising ammonium chloride.
8. The method according to claim 7, further comprising heating the
at least one third composition to a temperature less than about
140.degree. C.
9. The method according to claim 7, further comprising heating the
at least one third composition to a temperature between about
80.degree. C. and about 120.degree. C.
10. The method according to claim 7, further comprising heating the
at least one third composition to a temperature of about 90.degree.
C.
11. The method according to claim 1, wherein the adding the at
least one second composition to the at least one first composition
occurs over the course of between about 20 hrs and about 28
hrs.
12. The method according to claim 1, wherein the adding the at
least one second composition to the at least one first composition
occurs over the course of about 24 hrs.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Patent
Application No. 61/723,942, filed Nov. 8, 2012, entitled NANOWIRE
PREPARATION METHODS, COMPOSITIONS, AND ARTICLES, which is hereby
incorporated by reference in its entirety.
BACKGROUND
[0002] The general preparation of silver nanowires (AgNW, 10-200
aspect ratio) from silver ions is known. See, for example, Y. Xia,
et al., Angew. Chem. Int. Ed. 2009, 48, 60, and J. Jiu, et al.,
Mat. Chem. & Phys., 2009, 114, 333, each of which is hereby
incorporated by reference in its entirety. These include the
"polyol" process, in which a silver salt is heated in a polyol
(typically ethylene glycol (EG)) in the presence of
polyvinylpyrrolidinone (PVP, also known as polyvinylpyrrolidone),
yielding a suspension of AgNW in EG, from which the wires can be
isolated and/or purified as desired.
[0003] Methods of preparing silver nanowires from silver salts are
known, where the salt is added to the reaction mixture in more than
one step. See, for example, U.S. Pat. No. 8,052,773, US patent
application publication 2011/0174190, Chinese patent application
publication 1740405A, and Chinese patent 100342064C.
[0004] US patent application publication 2012/0063948A discloses
reduction of silver nitrate in the presence of ammonium
chloride.
SUMMARY
[0005] Some embodiments provide methods to prepare silver nanowires
comprising at least two stages.
[0006] At least a first stage provides a first composition
comprising 1,2-propylene glycol, polyvinylpyrrolidone (PVP), and
ammonium chloride. The PVP has weight average molecular weight
greater than about 15,000 g/mol, or between about 40,000 and about
60,000 g/mol, or about 50,000 g/mol. The first composition is
preferably provided at a temperature less than about 140.degree.
C., or between about 80.degree. C. and about 120.degree. C., or
about 90.degree. C.
[0007] In at least one second stage, a second composition
comprising 1,2-propylene glycol and silver nitrate is added to the
first composition over a time period that is at least about 16 hrs,
or between about 20 hrs and about 28 hrs, or about 24 hrs, during
which time at least some of the silver nitrate is reduced to silver
nanostructures, such as, for example, silver nanowires.
[0008] These and other embodiments may be understood from the
description, exemplary embodiments, examples, and claims that
follow.
DESCRIPTION
[0009] All publications, patents, and patent documents referred to
in this document are incorporated by reference herein in there
entirety, as though individually incorporated by reference.
[0010] U.S. Patent Application No. 61/723,942, filed Nov. 8, 2012,
entitled NANOWIRE PREPARATION METHODS, COMPOSITIONS, AND ARTICLES,
is hereby incorporated by reference in its entirety.
Introduction
[0011] Silver nanowires (AgNW) are a unique and useful wire-like
form of the metal in which the two short dimensions (the thickness
dimensions) are less than 300 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.
They are being examined as conductors in electronic devices or as
elements in optical devices, among other possible uses.
[0012] A number of procedures have been presented for the
preparation of AgNW. See, for example, Y. Xia, et al. (Angew. Chem.
Int. Ed. 2009, 48, 60), which is hereby incorporated by reference
in its entirety. These include the "polyol" process, in which a
silver salt is heated in a polyol (typically ethylene glycol (EG))
in the presence of polyvinylpyrrolidinone (PVP, also known as
polyvinylpyrrolidone), yielding a suspension of AgNW in EG, from
which the wires can be isolated and/or purified as desired.
Reducible Metal Ions and Metal Products
[0013] 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, in some
cases, be provided as silver nitrate.
[0014] 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.
Preparation Methods and Materials
[0015] 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. Applicants have observed that reproducibility can
be improved and variability reduced if such metal cation reduction
is carried out in at least two stages.
[0016] A first stage or stages provides a first composition
comprising 1,2-propylene glycol, polyvinylpyrrolidone (PVP), and
ammonium chloride. The
[0017] PVP has weight average molecular weight greater than about
15,000 g/mol, or between about 40,000 and about 60,000 g/mol, or
about 50,000 g/mol. The first composition is preferably provided at
a temperature less than about 140.degree. C., or between about
80.degree. C. and about 120.degree. C., or about 90.degree. C.
[0018] In some embodiments, the components of the first composition
are contacted with each other prior to heating. In some
embodiments, the first stage or stages may provide the first
composition in a series of sub-stages each providing some of the
components of the composition. Some of the components may be
provided in more than one sub-stage.
[0019] In at least some embodiments, the first composition may
further comprise silver nitrate. For example, a first portion of
the first composition may be provided comprising silver nitrate,
followed by a second portion of the first composition comprising
ammonium chloride.
[0020] In a second stage or stages, a second composition comprising
1,2-propylene glycol and silver nitrate is added to the first
composition over a time period that is at least about 16 hrs, or
between about 20 hrs and about 28 hrs, or about 24 hrs, during
which time at least some of the silver nitrate is reduced to silver
nanostructures, such as, for example, silver nanowires.
Nanostructures and Nanowires
[0021] In some embodiments, the metal product formed by such
methods is a nanostructure, such as, for example, a one-dimensional
nanostructure.
[0022] 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.
[0023] 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.
[0024] 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.
EXEMPLARY EMBODIMENTS
[0025] U.S. Patent Application No. 61/723,942, filed Nov.8, 2012,
entitled NANOWIRE PREPARATION METHODS, COMPOSITIONS, AND ARTICLES,
which is hereby incorporated by reference in its entirety,
disclosed the following twelve non-limiting exemplary
embodiments:
A. A method comprising:
[0026] providing at least one first composition comprising
1,2-propylene glycol, polyvinyl pyrrolidone, and ammonium
chloride;
[0027] adding at least one second composition to the at least one
first composition, the adding occurring over the course of at least
about 16 hrs, and the at least one second composition comprising
1,2-propylene glycol and silver nitrate; and
[0028] reducing at least a portion of the silver nitrate to silver
nanowires.
B. The method according to embodiment A, further comprising heating
the at least one first composition to a temperature less than about
140.degree. C.
[0029] C. The method according to embodiment A, further comprising
heating the at least one first composition to a temperature between
about 80.degree. C. and about 120.degree. C.
D. The method according to embodiment A, further comprising heating
the at least one first composition to a temperature of about
90.degree. C. E. The method according to embodiment A, wherein the
at least one first composition further comprises silver nitrate. F.
The method according to embodiment E, wherein providing the at
least one first composition comprises:
[0030] providing at least one third composition comprising silver
nitrate; and adding at least one fourth composition to the at least
one third composition, the at least one fourth composition
comprising ammonium chloride.
G. The method according to embodiment E, wherein providing the at
least one first composition comprises:
[0031] providing at least one third composition comprising
polyvinyl pyrrolidone;
[0032] forming at least one fourth composition by adding at least
one fifth composition to the at least one third composition, the at
least one fifth composition comprising silver nitrate; and
[0033] adding at least one sixth composition to the at least one
fourth composition, the at least one sixth composition comprising
ammonium chloride.
H. The method according to embodiment G, further comprising heating
the at least one third composition to a temperature less than about
140.degree. C. J. The method according to embodiment G, further
comprising heating the at least one third composition to a
temperature between about 80.degree. C. and about 120.degree. C. K.
The method according to embodiment G, further comprising heating
the at least one third composition to a temperature of about
90.degree. C. L. The method according to embodiment A, wherein the
adding the at least one second composition to the at least one
first composition occurs over the course of between about 20 hrs
and about 28 hrs. M. The method according to embodiment A, wherein
the adding the at least one second composition to the at least one
first composition occurs over the course of about 24 hrs.
EXAMPLES
Example 1
[0034] To a 500 mL reaction vessel was charged 430 mL propylene
glycol, 7.2 g of polyvinylpyrrolidone (50,000 weight average
molecular weight), and 2 mL of a 1 wt % solution of ammonium
chloride in propylene glycol. The mixture was stirred under
nitrogen until solids were in solution, followed by heating to
90.degree. C. A freshly prepared solution of 6 g AgNO.sub.3 in 36
mL propylene glycol was added dropwise over 64 h. After quenching
in an ice bath, the product was isolated by settling and
centrifugation to give silver nanowires with an average diameter of
40.23 nm and average length of 30.9 .mu.m, based on measurement of
at least 100 nanowires.
Example 2 (Comparative)
[0035] To a 500 mL reaction vessel was charged 430 mL propylene
glycol and 7.2 g of polyvinylpyrrolidone (50,000 weight average
molecular weight). The mixture was stirred under nitrogen until
solids were in solution, followed by heating to 90.degree. C. To
the mixture was added 0.2 mL of a solution of 6 g AgNO.sub.3 in 36
mL propylene glycol, followed by 1.14 mL of a 10 wt % solution of
tetrabutylammonium chloride in propylene glycol. After these
additions, 35.8 mL of a solution of 6 g AgNO.sub.3 in 36 mL
propylene glycol was added to the mixture.
[0036] This mixture was stirred at temperature for 24 hr. After
quenching in an ice bath, the product was isolated by settling and
centrifugation to give silver nanowires with an average diameter of
60 nm and average length of 15.7 .mu.m, based on measurement of at
least 100 nanowires.
Example 3
[0037] The procedure of Example 1 was repeated, changing the time
period for AgNO.sub.3 solution addition from 64 h to 24 h. The
resulting silver nanowires had an average diameter of 44.11 nm and
average length of 16.7 .mu.m, based on measurement of at least 100
nanowires.
Example 4
[0038] The procedure of Example 1 was repeated, changing the time
period for AgNO.sub.3 solution addition from 64 h to 67.3 h, and
changing the reaction temperature from 90.degree. C. to 75.degree.
C. The resulting silver nanowires had an average diameter of 57.2
nm and average length of 20.5 .mu.m, based on measurement of at
least 100 nanowires.
[0039] Example 5
[0040] To a reaction vessel was charged 2000 mL propylene glycol
and 33.5 g of polyvinylpyrrolidone (PVP, 50,000 weight average
molecular weight).
[0041] The mixture was stirred with nitrogen sparging until the PVP
dissolved. The mixture was then heated to 91.degree. C. A freshly
prepared solution of 28.08 g AgNO.sub.3 in 168 mL propylene glycol
was pumped into the reaction vessel at a rate of 0.949 mL/min for 5
min. The silver nitrate pump was then stopped for 5 min. The silver
nitrate pump was then restarted at a rate of 34.6 mL/hr and was
allowed to run for 30.6 hr. At the time the silver nitrate pump was
restarted, 9.4 mL of a 1 wt % solution of ammonium chloride in
propylene glycol was pumped into the reaction mixture at a rate of
34.6 mL/hr. The reaction mixture was held for 25 min after the
silver nitrate pump was shut off. The reaction vessel was then
allowed to cool to room temperature. The resulting silver nanowires
had an average diameter of 43.8 nm and average length of 22.9
.mu.m, based on measurement of at least 100 nanowires.
[0042] Example 6 To a reaction vessel was charged 8000 mL propylene
glycol and 134.0 g of polyvinylpyrrolidone (PVP, 50,000 weight
average molecular weight). The mixture was stirred with nitrogen
sparging until the PVP dissolved. The mixture was then heated to
91.degree. C. A freshly prepared solution of 112.32 g AgNO.sub.3 in
672 mL propylene glycol was pumped into the reaction vessel at a
rate of 0.44 mL/min for 5 min. The silver nitrate pump was then
stopped for 5 min.
[0043] The silver nitrate pump was then restarted and was allowed
to run for 26.7 hr. At the time the silver nitrate pump was
restarted, 37.6 mL of a 1 wt % solution of ammonium chloride in
propylene glycol was pumped into the reaction mixture at a rate of
150 mL/hr. The reaction mixture was held for 66 min after the
silver nitrate pump was shut off. The reaction vessel was then
allowed to cool to room temperature. The resulting silver nanowires
had an average diameter of 39.8 nm and average length of 17.6
.mu.m, based on measurement of at least 100 nanowires.
[0044] The invention has been described in detail with particular
reference to a presently preferred embodiment, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention. The presently disclosed
embodiments are therefore considered in all respects to be
illustrative and not restrictive. The scope of the invention is
indicated by the appended claims, and all changes that come within
the meaning and range of equivalents thereof are intended to be
embraced therein.
* * * * *