HK1131094B - Nanoparticles, methods of making, and applications using same - Google Patents

Description

Nanoparticles, method for the production thereof and use thereof

RELATED APPLICATIONS

This application claims priority from U.S. provisional application serial No. 60/791,325, filed on 12.4.2006, which is incorporated herein by reference in its entirety.

Background

New and better nanostructured materials are needed for various applications in various different industries, including biotechnology, diagnostic technology, energy and electronic technology. For example, electronic device manufacturers are constantly striving to reduce costs and increase the functionality of electronic devices and components. One emerging strategy for reducing cost is to print electronic devices directly onto low cost plastic films using solution-based inks. The printed electronic device refers to a technology for manufacturing a functional electronic device in a high-yield and low-cost two-reel (R2R) manner using a method (such as inkjet printing, gravure printing, screen printing, flexo printing (flexo printing), offset printing (off-set printing), etc.) that has been used in the printing industry. An example of a printed electronic device is the use of ink jet printing of metal nanoparticle patterns to form conductors to build circuits. This method is discussed, for example, in "Applications of printing Technology in Organic Electronics and display Fabric" by V.Subramanian, published by Half Moon Bay MasklessLithographics Workshop, DARPA/SRC, Half Moon Bay, CA, Nov9-10, 2000.

The nanoparticle material properties may differ from the corresponding bulk material. For example, one of the most characteristic features of nanoparticles is the size-dependent decrease in the melting point of the surface. (Size effect on the porous particles "by Buffat et al (Physical Review A, Vol. 13, No. 6, month 6 1976, p. 2287-. An example has been shown in "Plastic-Compatible Low Resistance Performance specific gold semiconductors for Flexible Electronic" (Journal of Electrochemical Society, Vol. 150, p. 412. 417, 2003). To process nanoparticle inks on plastic substrates, it is necessary to have the particle sintering temperature below the glass transition temperature (Tg) of the substrate material, which is typically below 200 ℃. As indicated in the above documents, nanoparticles having a size of less than 10nm are required.

There is still a need to be able to find better routes for nanoparticle synthesis, especially methods that are very small in size and industrially feasible. For example, due to the difficulty of controlling particle nucleation and growth, it is desirable to synthesize inorganic nanoparticles having a size of less than 20nm, especially less than 10nm, in a liquid medium by industrial mass production.

U.S. patent publication 2006/0003262 to Yang et al and 2006/0263725 to Nguyen et al describe the manufacture and use of nanoparticles with the use of dyes. Here, the solution method of nanoparticle synthesis is briefly described, but the method focuses on many factors important for industrialization, including: the general applicability of this approach is limited to a variety of metals and materials, including, for example, silver and semiconductors; limiting the use of thiol stabilizers to avoid the formation of unwanted sulfides; and limited use of phase transfer catalysts. For example, some phase transfer catalysts may be toxic.

There is still a need to find better, more efficient, more versatile methods for expanding the mass production of nanoparticles in a low cost process.

Disclosure of Invention

Various embodiments described and claimed herein include methods of making compositions, inks, methods of using articles and devices, and the like.

An implementation provides a method, comprising:

(a) providing a first mixture comprising at least one nanoparticle precursor and at least one first solvent for the nanoparticle precursor, wherein the nanoparticle precursor comprises a salt comprising a cation comprising a metal;

(b) providing a second mixture comprising at least one reactive moiety that reacts with the nanoparticle precursor, and at least one second solvent for the reactive moiety, wherein the second solvent phase separates when mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer, wherein upon combination the first and second mixtures phase separate and form nanoparticles.

Another embodiment provides a method comprising:

(a) providing a first mixture comprising at least one nanoparticle precursor and at least one first solvent for the nanoparticle precursor, wherein the nanoparticle precursor comprises a salt comprising an inorganic cation;

(b) providing a second mixture comprising at least one reactive moiety that reacts with the nanoparticle precursor, and at least one second solvent for the reactive moiety, wherein the second solvent phase separates when mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer, wherein upon combination the first and second mixtures phase separate and form nanoparticles.

A method, comprising:

(a) providing a first mixture comprising at least one metal-containing nanoparticle precursor and at least one first solvent;

(b) providing a second mixture comprising at least one portion reactive with the nanoparticle precursor and at least one second solvent, wherein the second solvent phase separates when mixed with the first solvent; wherein the first and the second mixture are provided substantially without the use of a phase transfer catalyst; and

(c) combining the first and second mixtures in the presence of a surface stabilizer, wherein the first and second mixtures phase separate and form nanoparticles.

A method, comprising:

(a) providing a first mixture comprising at least one nanoparticle precursor and at least one first solvent,

(b) providing a second mixture comprising at least one moiety reactive with the nanoparticle precursor, and at least one second solvent, wherein the second solvent phase separates when mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer comprising an amino or carboxylic acid group, wherein the first and second mixtures phase separate and form nanoparticles.

Also provided is a method comprising:

(a) providing a first mixture comprising at least one first solvent and at least one nanoparticle precursor, wherein the nanoparticle precursor comprises a metal other than gold;

(b) providing a second mixture comprising at least one second solvent and at least one reactive moiety that reacts with the nanoparticle precursor, wherein the second solvent phase separates when mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer, wherein the first and second mixtures phase separate and form nanoparticles.

Also provided is a method comprising:

(a) providing a first mixture comprising at least one first solvent and at least one nanoparticle precursor, wherein the nanoparticle precursor comprises a metal;

(b) providing a second mixture comprising at least one second solvent and at least one reactive moiety that reacts with the nanoparticle precursor, wherein the second solvent phase separates when mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer that is not a thiol, wherein the first and second mixtures phase separate and form nanoparticles.

Another embodiment is a method comprising:

at least two precursor materials are reacted in the presence of at least one surface stabilizer and two immiscible solvents to form inorganic nanoparticles at an interface of the solvents, wherein a first precursor comprises a metal ion and a second precursor comprises a reducing agent.

Another embodiment provides a method consisting essentially of:

(a) providing a first mixture consisting essentially of at least one nanoparticle precursor and at least one first solvent for the nanoparticle precursor, wherein the nanoparticle precursor consists essentially of a salt containing cations comprising a metal;

(b) providing a second mixture consisting essentially of at least one reactive moiety that reacts with the nanoparticle precursor and at least one second solvent for the reactive moiety, wherein the second solvent phase separates when mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer, wherein upon combination the first and second mixtures phase separate and form nanoparticles.

Another embodiment provides a composition comprising:

nanoparticles comprising an amine or carboxylic acid surface stabilizer dispersed in at least one solvent, wherein the concentration of the nanoparticles is from about 1 wt% to about 70 wt%, and the nanoparticles have an average size of from about 1nm to about 20nm and exhibit a monodispersity of about 3nm or less standard deviation.

Another embodiment provides a composition comprising metal nanoparticles that exhibit a DSC sintering temperature exotherm peak between about 110 ℃ to about 160 ℃.

The advantages include: easy to manufacture, widely compatible with low cost methods used in the chemical industry, scalability for full scale production (scalability), good control of particle size and dispersibility, good monodispersity, ultra small particle size, low annealing temperature, short processing time, high final conductivity, universal applicability to different materials and surface chemistry and solvent systems, good sintering behavior (including curability at room temperature with heat, light or laser), and the ability to form good and commercially useful materials from nanoparticles.

Drawings

Fig. 1 is a TEM micrograph of Ag nanoparticles.

Fig. 2 shows SANS data for Ag nanoparticles.

FIG. 3 shows UV-VIS data of Ag nanoparticles.

Fig. 4 shows DSC of Ag nanoparticles.

Fig. 5 is a thermogravimetric analysis (TGA) of Ag nanoparticles.

Fig. 6 is a TEM micrograph of ZnO nanoparticles.

FIG. 7(a) is an SEM micrograph of silver nanoparticles about 5nm in diameter cast on an aluminum substrate.

Fig. 7(b) is an SEM micrograph of a silver film on a PET plastic substrate from silver nanoparticles cast on the substrate and annealed at a temperature of about 150 ℃.

Detailed Description

Introduction to the design reside in

The entire content of prior U.S. provisional application serial No. 60/791,325 filed on 12.4.2006 is incorporated herein by reference.

All references cited herein are incorporated by reference in their entirety as if fully set forth.

Nanostructures and nanoparticles, as well as methods of making, characterizing, processing, and using the same, are known in the art. See, for example, Introduction to nanotechnology by Poole, Owens, 2003 (including chapter 4); "Chemistry and Properties of Nanocrystals of Difference Shapes" by Burka et al (chem.Rev., 2005, 105, 1025-); "Controlled Synthesis of high Quality Semiconductor Nanocrystals," Peng et al (Struc Bond, 2005, 118: 79-119); "Synthesis, Properties, and applied perspectives of Hybrid nanocrystalline Structures," by Cozzoli et al (chem. Soc. Rev., 2006, 35, 1195-.

Further technical descriptions of Printed electronics can be found, for example, in Printed Organic and molecular electronics (Kluwer, 2004), edited by d.

Embodiments of the present invention describe compositions comprising inorganic nanoparticles, and methods of forming, and methods of using the same.

In one aspect of an embodiment, a method of synthesis includes combining a mixture comprising a nanoparticle precursor with a mixture comprising a reactive moiety in the presence of a surface stabilizer.

Throughout this disclosure, "first mixture" and "second mixture" refer to different mixtures. Likewise, "first solvent" and "second solvent" and "first nanoparticle precursor" and "second nanoprecursor" refer to different solvents and different precursors, respectively.

Providing a mixture

For example, the mixture may be provided by purchase or direct formulation. One or more method steps may be used or avoided in the providing step. For example, in one embodiment, the first and second mixtures are provided substantially without, or entirely without, use of a phase transfer catalyst. Phase transfer catalysts are known in the art and include, for example, alkylammonium salts (including tetraalkylammonium salts (R)₄NX, where X is an anion such as halide, chloride, bromide, or iodide)), crown ethers and macrocyclic amine ethers, and other moieties that exhibit host-guest characteristics. Avoiding this use may eliminate processing steps. For example, any amount of phase transfer catalyst may be less than 1g, less than 100mg, or less than 10mg, see, e.g., working examples 1 and 2 for formulations without phase transfer catalyst.

One step includes providing a mixture that includes providing a first mixture and providing a second mixture. Mixtures are generally known in the art.

The mixture used herein may be a homogeneous or heterogeneous mixture, although in many cases a homogeneous mixture is used. Preferably, at least one of the mixtures is a homogeneous mixture, or a very dispersed mixture acting as a solution, or a solution. Typically, the mixture comprises at least two components, such as precursors, solvents, surface stabilizers, and/or reactive moieties. A mixture may comprise more than one of each component. The mixture may further comprise a surfactant or emulsifier to achieve a higher degree of homogeneity. In some embodiments, the two mixtures are combined to form nanoparticles. However, in other embodiments, a mixture of two or more can be combined to form the nanoparticles.

The volume of the first mixture may be greater than the volume of the second mixture. For example, if the first mixture is an organic mixture and the second mixture is an aqueous mixture, then an organic mixture having a greater volume than the aqueous mixture may be used. The volume may be at least twice as much as the volume of the water mixture.

Solvent(s)

Solvents are generally known in the art. Suitable solvents may be aqueous or organic in nature and comprise more than one component. The solvent may be adapted to dissolve or highly disperse components such as the nanoparticle precursor, surface stabilizer, or reactive moiety. The solvent may be selected based on the type of mixture desired, the solubility of the solutes and/or precursors therein, or other factors.

After combining the mixture, at least two solvents phase separate. Phase separation is understood to mean two separate liquid phases which are observable to the naked eye.

In a preferred embodiment, at least the solvent from one mixture (e.g., the "first mixture") is separated from the solvent from a different mixture (e.g., the "second mixture"). Also, the solvents are preferably immiscible with each other. In a preferred embodiment, the organic mixture is combined with the aqueous mixture to form nanoparticles.

Water in purified form, such as distilled and/or deionized water, may be used. The pH may be a normal ambient pH, which is slightly acidic due to carbon dioxide. For example, the pH may be from about 4 to about 10, or from about 5 to about 8.

In some embodiments, the one or more solvents comprise a saturated or unsaturated hydrocarbon compound. The hydrocarbon compound may further comprise an aromatic, an alcohol, an ester, an ether, a ketone, an amine, an amide, a thiol, a halogen, or any combination of the moieties.

In one embodiment, the first solvent comprises an organic solvent and the second solvent comprises water. In another embodiment, the first solvent comprises a hydrocarbon and the second solvent comprises water.

Phase separation

As is known in the art, the first and second solvents, when mixed, may phase separate and may be immiscible. As is known in the art, phase separation can be detected under normal laboratory ambient temperature and pressure conditions by mixing approximately equal volumes of solvent and allowing the mixture to settle, and then looking for an interface. The solvent may be relatively pure, for example at least about 90 wt% pure, or at least 95 wt% pure, or at least about 99 wt% pure.

Table 1 lists examples of immiscible solvent combinations, but is in no way intended to limit the scope of solvents that may be used to practice embodiments of the present invention.

TABLE 1 examples of immiscible solvents that can phase separate

Solvent(s)	Are immiscible in
		Acetonitrile carbon tetrachloride trichloromethane cyclohexane 1, 2-dichloroethane dichloromethane diethyl ether dimethylformamide dimethyl sulfoxide ethyl acetate heptane methanol methyl-tert-butyl ether pentane toluene 2, 2, 4-trimethylpentane water	Cyclohexane, heptane, hexane, pentane, 2, 4-trimethylpentane aqua acetonitrile, dimethylformamide, dimethyl sulfoxide, methanol, aqua dimethyl sulfoxide, aqueous cyclohexane, heptane, hexane, pentane, 2, 4-trimethylpentane, diethyl ether aqua acetonitrile, dimethylformamide, dimethyl sulfoxide, methanol, aqueous cyclohexane, heptane, hexane, pentane, 2, 4-trimethylpentane aqua acetonitrile, dimethylformamide, dimethyl sulfoxide, methanol, aqueous carbon tetrachloride, trichloro chloroformMethane, cyclohexane, 1, 2-dichloroethane, dichloromethane, diethyl ether, dimethylformamide, ethyl acetate, heptane, hexane, methyl-tert-butyl ether, pentane, toluene, 2, 4-trimethylpentane

Nanoparticle precursors or reactive moieties

The nanoparticles can be made from precursors or nanoparticle precursors or reactive moieties. In many cases, only one reaction step is required to convert the nanoparticle precursor to form the nanoparticles. In many cases, two or more (or preferably two) nanoparticle precursors are reacted together to form nanoparticles. Nanoparticle precursors, as used herein, include any compound or reactive moiety, for example, comprising a covalent bond, an ionic bond, or a combination thereof. The nanoparticle precursor can be any compound that includes metal atoms, semi-metal atoms, non-metal atoms, or any combination thereof. The nanoparticle precursors are chemically combined to form nanoparticles having the desired composition.

The nanoparticle precursor can comprise a salt comprising a cation comprising a metal. The salt anion may be an inorganic anion (e.g., a halide), or an organic anion, such as a conjugate base of a carboxylic acid compound (e.g., a stearate).

In one embodiment, the one or more nanoprecursors comprise a metallic element, such as a transition metal. For example, the one or more precursors can include Zn, Au, Ag, Cu, Pt, Pd, Al, or combinations thereof.

In one embodiment, the nanoparticle precursor contains a metal other than gold.

In another embodiment, one or more nanoparticle precursors comprise a semiconductor material, such as a group IV, I-VII, II-VI, or III-V semiconductor material, or a combination thereof. For example, one or more precursors may include ZnO, ZnS, TiO₂、Si、Ge、CdSe、CdS、GaAs、SnO₂、WO₃Or a combination thereof.

The nanoparticle precursor can include a reactive moiety that reacts with another nanoparticle precursor. For example, the reactive moiety may be free of metal, while the nanoparticle precursor with which it is reacted comprises a metal.

The reactive moiety may be, for example, a reducing agent. Nanoparticles can be prepared by combining a reducing agent with a cationic species, such as a metal cation. Thus, one embodiment includes combining at least two nanoparticle precursors, wherein at least one precursor provides cationic species (e.g., Ag)⁺、Zn²⁺Etc.), and at least one other precursor or reactive moiety provides the reducing agent. Essentially, any reducing agent can be used to convert the ionic species into nanoparticles. One example is a hydride compound. Non-limiting examples of reducing agents include: NaBH₄、LiBH₄、LiAlH₄Hydrazine, ethylene glycol, ethylene oxide, alcohol, or combinations thereof.

The reactive moiety may also comprise a hydroxyl-generating moiety or compound or a base (such as sodium hydroxide or potassium hydroxide).

Surface stabilizer

Surface stabilizers generally describe any chemical species having an affinity for inorganic nanoparticles. Preferably, the surface stabilizer is bonded to the surface of the nanoparticle via covalent bonds, Van der waals forces (Van der waals), hydrogen bonds, or a combination thereof, thereby forming a surface stabilizing layer. In addition, the surface stabilizer also prevents the nanoparticles from growing to an excessively large size, or from agglomerating into larger particles. Preferably, the nanoparticles formed according to this embodiment are coated or coated with a stabilizer layer. In some cases, it may be desirable to use more than one surface stabilizer.

The chemical composition of the surface stabilizer can vary widely, provided there is good interaction with the nanoparticles. In some examples, the stabilizer comprises a hydrocarbon. Preferably, the hydrocarbon comprises a carbon chain having from 2 to 30 carbon atoms or having from 10 to 25 carbon atoms. The hydrocarbon may further comprise, for example, thiol, hydroxyl, amine, or carboxyl moieties, or combinations thereof. Alternatively, the stabilizer may be considered a substituted amine or a substituted carboxylic acid.

In one embodiment, the surface stabilizer may be represented by the formula:

(I)(R)_n-X

wherein R may be a hydrophobic moiety, free of Lewis basicity; and X can be a hydrophilic moiety, providing lewis basicity; and n may be, for example, 1 to 4, or 1, 2, 3, or 4. For example, R may represent a linear or branched alkyl group comprising an alkylene group and a terminal methyl group. X may be an organic functional group comprising a nitrogen, oxygen or sulfur atom. For example, R can be alkyl, n can be 1, and X can be-NH₂. Or R may be an alkyl group, n may be 1, and X may comprise-COOH or-COOR (such as in a carboxylic acid or carboxylic acid ester).

In an embodiment, the surface stabilizer, the first solvent and the second solvent are adapted such that when the first solvent separates from the second solvent and forms an interface, the surface stabilizer migrates to the interface.

In one embodiment, the surface stabilizer comprises at least one alkylene group, and a nitrogen atom or an oxygen atom. The alkylene group may be, for example, a C2 to C30 alkylene group. It may be straight or branched.

In one embodiment, the surface stabilizer comprises an amino compound or a carboxyl compound or a thiol compound.

In one embodiment, the surface stabilizer comprises an amino compound or a carboxyl compound.

The first mixture may comprise a surface stabilizer. The second compound may be free of surface stabilizers. Alternatively, the second mixture may comprise a surface stabilizer.

In one embodiment, the surface stabilizer detaches from the surface of the nanoparticle (de-association) at a temperature of, for example, about 50 ℃ to about 250 ℃.

Combination of

Combinatorial approaches are known in the art of synthesis. Combining may refer to an operation of bringing two or more entities (entities), such as a mixture, into physical contact with each other. For example, pouring the two mixtures into a common container (e.g., vat, vessel, beaker, flask, etc.) results in a combination of the two mixtures. The combination of mixtures may also include mixing them. The combination may also be a more controlled step over time, such as adding only a few portions or adding dropwise. For example, in combination, the two mixtures may be placed in the same container and mechanically mixed. Agitation, stirring, injection, dropwise addition, and the like may be used. One skilled in the art can adapt the combination method to achieve the desired results for different embodiments.

In one embodiment, the combination may be performed without externally applying heat or cooling. The reaction temperature may be, for example, from 10 ℃ to about 50 ℃, or from about 20 ℃ to about 35 ℃.

No pressure and/or vacuum need be applied during the combining step. The reaction pressure may be, for example, 700 torr to 820 torr.

Normal laboratory work and industrial production ambient temperatures and pressures can be used. The combination can be carried out batchwise, simultaneously or continuously or semi-continuously, such as dropwise addition. For example, the second mixture may be added to the first mixture continuously or semi-continuously.

Nanoparticles

Nanoparticles can be collected, isolated or purified from the area where the combination is performed. For example, phase separation may be performed. The solvent may be removed. The particles can be precipitated and washed.

The yield of collected nanoparticles may be, for example, at least 50%, or at least 70%, or at least 90%, or at least about 95%, or at least about 98% by weight.

The shape of the nanoparticles is not particularly limited, and may be, for example, generally spherical or non-spherical, or elongated (elongated) having, for example, an aspect ratio. For example, the aspect ratio may be at least 1.5:1 or at least 2:1 or at least 3:1, and in the case of higher aspect ratios, rod, wire and needle structures may be formed. In some embodiments, these elongated structures may be a relatively small portion of the product, for example less than 30 wt.%, or less than 20 wt.%, or less than 10 wt.%.

Without wishing to be bound by theory, it is believed that the separation of the precursor material in the immiscible solvent effectively controls the reaction rate of forming the inorganic nanoparticles by limiting or substantially limiting the contact of the nanoparticle precursor and the reactive moiety to the interfacial region of the immiscible solvent. Thus, the formation and growth rate of inorganic nanoparticles may be limited by the amount of nanoparticle precursor species that has diffused from the solvent host to the immiscible solvent interface.

Reactions between the nanoparticle precursors can result in the formation of nanoparticles having surface stabilizers adsorbed thereon or otherwise providing dispersibility. Due to the immiscibility of the solvent, the reaction between the precursor material and the reactive moiety may be completely or incompletely focused at the interface of the solvent. Furthermore, the surface stabilizer present at the interface maintains the average nanoparticle size in a limited range, typically between about 1nm to about 1000nm, preferably between about 1nm and about 100nm, more preferably between about 1nm and about 20nm, and most preferably between about 2nm and about 10 nm.

As used herein, nanoparticles refer to particles having a diameter between about 1000nm and about 1 nm. In embodiments of the present invention, the nanoparticles formed may be a function of, among other factors, the solvent, the chemical composition and concentration of the precursor material, the chemical composition and concentration of the surface stabilizer, the processing procedure, the temperature, any combination thereof. Thus, the size of nanoparticles synthesized according to embodiments of the present invention is well controlled in the range of 1nm to 1000nm, preferably 1nm to 100nm, more preferably 1nm to 20nm, most preferably 2nm to 10nm, and the particle size distribution is very narrow.

The particle size may be measured by methods known in the art, including, for example, a TEM or SEM, which may be adapted to the size of the particle. For particles that are roughly spherical, the particle size may approach the diameter of a sphere. The particle size can be measured without including a stabilizer layer removable from the nanoparticles. The thickness of the stabilizer layer is typically thin and smaller than the diameter of the nanoparticles.

Monodispersity can be measured by particle counting methods and can exhibit a size distribution with a standard deviation of, for example, about 3nm or less, or about 2nm or less. For example, metal and silver nanoparticles may exhibit an average particle size of 5.4nm nanometers with a standard deviation of 1.4nm or about 26%, as measured by a size of about, e.g., 750 nanoparticles from about 20 TEM micrographs. An example of a TEM micrograph is shown in figure 1.

To more accurately determine the overall average nanoparticle size and size distribution, Small Angle Neutron Scattering (SANS) techniques may also be applied. For example, a cold neutron beam with a wavelength of 6 angstroms can be directed to a deuterated toluene solution containing 10 wt% nanoparticles (e.g., Ag nanoparticles), and the intensity of scattered neutrons can be recorded as a function of scattering angle, which is further converted to absolute scattering cross-sections as a function of neutron momentum transfer vector, as shown in fig. 2. Deuteration of the solvent helps to ensure sufficient scattering length density contrast between the nanoparticles (e.g., silver), surface stabilizer, and solvent, allowing SANS to record structural information for both the nanoparticle core (e.g., Ag) and the organic shell. Subsequent evaluation of SANS data using a core-shell model and Shultz distribution function (solid line across symbols as the most preferred fit) revealed, for example, that the average diameter of the Ag core was 4.6nm, and the thickness of the organic shell in toluene was 0.6 nm. Furthermore, the standard deviation of the diameters of the Ag nanoparticles is, for example, 1.1nm or about 24%. The SANS results are consistent with, but more guaranteed than, TEM micrographs, as they are averaged over the macroscopic sample volume.

An embodiment provides nanoparticles comprising Ag, Cu, Pt, Pd, Al, Sn, In, Bi, ZnS, ITO, Si, Ge, CdSe, GaAs, SnO₂、WO₃、SnS:Mn、ZnS:Tb、SrS、SrS:Cs、BaAl₂S₄、BaAl₂S₄Eu, or a combination thereof.

Exclusion

Basic and novel embodiments include formulations to the exclusion or substantial exclusion of components and method steps that are detrimental to the desired results. For example, it may produce impurities or may be economically inefficient for industrialization.

For example, one embodiment provides for providing the first mixture without using a phase transfer catalyst.

In another embodiment, the salt anion is metal free.

In another embodiment, the surface stabilizer consists essentially of at least a substituted amine or a substituted carboxylic acid, wherein the substituent comprises from 2 to 30 carbon atoms and no sulfur is present.

In another embodiment, the surface stabilizer consists essentially of an amino compound or a carboxylic acid compound, and no sulfur is present.

In another embodiment, the first mixture consists essentially of the surface stabilizer, and the second mixture is free of the surface stabilizer.

In another embodiment, the combination is performed without external application of heat or cooling.

In another embodiment, the combination is performed without the application of pressure or vacuum.

In another embodiment, the first mixture and the second mixture are free of compounds that can react with each other to form a sulfide.

In another embodiment, the method eliminates the complex processing steps found in the prior art such as vacuum deposition and aerosol.

Ink formulation

The ink may be a formulation from nanoparticles. For example, one embodiment provides a composition comprising nanoparticles comprising an amine or carboxylic acid surface stabilizer dispersed in at least one solvent, wherein the concentration of nanoparticles is from about 1 wt% to about 70 wt%, or from about 5 wt% to about 40 wt%, and the nanoparticles have an average size of from about 1nm to about 20nm, or from about 2nm to about 10nm, and a monodispersity of about 3nm or less, or about 2nm or less.

In one embodiment, the concentration is from about 10% to about 50% by weight.

In one embodiment, the solvent is an organic solvent, such as a hydrocarbon, e.g., cyclohexane.

The ink may be formulated using known film or pattern forming methods, such as inkjet printing or spin coating. Can meet the requirements of solution stability and storage life.

Other ingredients may be added to the ink, such as dyes, antioxidants, viscosity modifiers, and surface adhesion promoters.

In silver nanoparticles, e.g. dispersed in e.g. cyclohexane, UV-VIS characterization can be performed and may show a sharp absorption spectrum peak, e.g. in the vicinity of e.g. 400 to 450 nm. The absorption peak may be relatively sharp and starts at about 325nm and ends at about 500nm, as shown in fig. 3.

Film formation and patterning

Methods known in the art can be used to convert nanoparticles and inks into solid films and coatings and layers, whether patterned or not. The thickness of the film may be, for example, about 1 micron or less, or about 500nm or less, or about 1nm to about 1000nm, or about 10nm to about 750 nm.

The printing process can be used to print on paper, plastics and fabrics. Common printing equipment may be used including, for example, screen printing, flexography, gravure, and lithography. A direct writing method may be used. Ink jet printing, including drop-on-demand ink jet printing, can be used.

The surface stabilizing material may be released by curing at room temperature by heat or light (e.g., laser or UV light). Sintering and annealing may be performed.

The film can be characterized by electrical properties, including conductivity and resistivity.

The conductivity may be at least 10⁴S/cm. The resistivity can be less than 10^-4ohm/cm. The resistivity was found to be only four times or less, or three times or less, or two times or less, or 1.5 times or less than that of the pure metal.

Film substrates are known in the art and include, for example, flexible materials including plastics and composites that may be optionally coated prior to application of the nanoparticles. Plastics include synthetic polymers such as PET, and high temperature polymers including, for example, polyimides.

Melting characteristics of nanoparticles

Nanoparticles can be produced having a surface melting temperature below the melting temperature of the bulk material. For example, the surface melting temperature may be from 50 ℃ to about 200 ℃, or from about 75 ℃ to about 175 ℃, or from about 90 ℃ to about 160 ℃.

The melting temperature can be measured by, for example, the DSC method, as shown in fig. 4.

Sintering characteristics of nanoparticles

In the most preferred embodiment of the present invention, the conductive nanoparticles (which are sintered at low temperature to form a conductive material on the substrate) have a particle size of about 2nm to about 10 nm. It has been demonstrated in the following examples that silver and gold nanoparticles having a size of about 2nm to about 10nm can be sintered at temperatures below 200 ℃ to form highly conductive materials on a substrate. The processing temperature is much lower than the melting temperature of silver and gold. The conductivity of the metal film after sintering of the nanoparticles is almost as high as that of the metal film treated by CVD. The method is generally applicable to conductive inorganic nanoparticles including, but not limited to, Ag, Au, Cu, Pt, Pd, Al, Sn, In, Bi, ZnS, and ITO.

Sintering can be viewed as an exotherm between about 110 ℃ to about 160 ℃, or about 120 ℃ to about 140 ℃ in a DSC (fig. 4). An exothermic peak was observed.

TGA analysis (fig. 5) can exhibit weight loss due to loss of surface stabilizer, for example, in the vicinity of 100 ℃ to about 200 ℃.

General examples of formation of metal (silver) nanoparticles

An example of a conductive nanoparticle is a silver nanoparticle. In this example, one precursor material is a reagent containing silver ions (such as silver acetate) dissolved in a first solvent (such as toluene), and the other precursor material is a reducing agent (such as sodium borohydride NaBH)₄) Dissolved in a second solvent (such as water) that is immiscible with the first solvent. In the presence of other reducing agents, such as LiBH₄、LiAlH₄Hydrazine, ethylene glycol, ethylene oxide based chemicals and alcohols, and the like. These precursor materials in immiscible solvents are mechanically mixed in the presence of a surface stabilizer for the silver nanoparticles. The surface stabilizer may be a substituted amine or a substituted carboxylic acid having a substituent of 2 to 30 carbons. Producing surface stabilizer coated silver nanoparticles having a size in the range of 1nm to 1000nm, preferably 1nm to 100nm, more preferably 1nm to 20nm, most preferably 2nm to 10 nm. A TEM micrograph of silver nanoparticles synthesized in this way is shown in fig. 6.

Nanoparticles formed according to this method exhibit special characteristics due to their relatively high monodispersity (i.e., between 1nm and about 20 nm) in diameter. For example, the silver nanoparticle melting temperature is significantly reduced from its bulk melting temperature of 962 ℃ to below 200 ℃. This property will allow the nanoparticles to form conductive patterns or lines on the substrate when processed at temperatures below 200 ℃. These materials find wide application in the manufacture of printed electronic devices on substrates. Other examples of nanoparticles of conductive materials include, but are not limited to, Au, Cu, Pt, Pd, Al, Sn, In, Bi, ZnS, and ITO.

General examples of semiconductor (zinc oxide) nanoparticle formation

In another preferred embodiment of the invention, nanoparticles of a semiconductive material are synthesized. An example of semiconducting nanoparticles is zinc oxide nanoparticles. In this example, one precursor material is a reagent containing zinc ions (such as zinc stearate) dissolved in a first solvent (such as toluene), and the other precursor material is a reagent that generates hydroxyl groups (such as sodium hydroxide) dissolved in a second solvent (such as water) that is immiscible with the first solvent. By mechanically blending the precursor materials in these immiscible solvents in the presence of surface stabilizers (such as substituted amines or substituted carboxylic acids) for the zinc oxide nanoparticles, surface-coated zinc oxide nanoparticles are produced with sizes in the range of 1nm to 1000nm, preferably 1nm to 100nm, more preferably 1nm to 20nm, most preferably 2nm to 10 nm. A TEM micrograph of ZnO nanoparticles synthesized in this way is shown in fig. 6.

The nanoparticles produced with the process disclosed in the present invention exhibit special properties due to their size dispersion size in the nanometer size, in particular in the size of 1nm to 20 nm. For example, the sintering temperature of the zinc oxide nanoparticles is significantly reduced from its bulk melting temperature of 1975 ℃ to below 400 ℃. This property will allow the nanoparticles to form a semiconducting film or device on the substrate when processed at temperatures below 400 ℃. Other examples of nanoparticles of semiconductive materials include, but are not limited to, Si, Ge, CdSe, and GaAs.

In a further preferred embodiment of the present invention, nanoparticles of electroluminescent materials are synthesized in the process according to the invention. Examples of nanoparticles of electroluminescent materials include, but are not limited to ZnS, ZnS: Mn, ZnS: Tb, SrS: Cs, BaAl₂S₄And BaAl₂S₄:Eu。

The low temperature sintering process of the nanoparticles synthesized in the method of the present invention also exhibits unique thermal properties. This feature distinguishes the nanoparticle sintering process from the conventional bulk material melting process. Conventional bulk melting processes typically exhibit an endothermic process during phase transformation of the material.

Accordingly, disclosed herein is a general method of synthesizing inorganic nanoparticles having a size in the range of 1nm to 1000nm, preferably 1nm to 100nm, more preferably 1nm to 20nm, with desirable material properties. The method comprises a multiphase solution based reaction, wherein the system comprises at least two precursor materials and at least one surface stabilizer. This approach presents advantages over other approaches in the field due to its simplicity, controllability, and scalability. The inorganic nanoparticles synthesized by the process of the present invention can be sintered into electrically functional materials at temperatures well below the melting temperature of the bulk material, preferably below 250 ℃. The electrically functional materials sintered from the inorganic nanoparticles synthesized by the method of the present invention have demonstrated superior properties and performance as a class of printable materials for use in the manufacture of printed electronic devices.

Applications of

The nanoparticles may be formed into a film having desired properties due to the materials in the nanoparticles, although other materials may be added or used with the nanoparticles as necessary. For example, the nanoparticles may be formed into a film having conductivity due to the material in the nanoparticles, or the nanoparticles may be formed into a semiconductive film in a doped or undoped state having semiconductivity due to the material in the doped or undoped state in the nanoparticles, or the nanoparticles may be formed into an electroluminescent film having electroluminescence due to the material in the nanoparticles.

Applications of nanoparticles are diverse and may range from biotechnology, nanomedicine, diagnostic technology, printed electronics, displays, OLEDs, PLEDs, SMOLEDs, transistors, thin film transistors, field effect transistors, solar cells, sensors, biosensors, medical diagnostic technology, nanocomposites, and the like. In particular, these materials may be used to fabricate printed semiconducting devices, such as TFTs and TFDs, on a substrate. Additional examples include flexible flat panel displays, RFID antennas and integrated circuits, Printed Circuit Boards (PCBs), mirrors and metal coatings, flexible digital watches, electronic newspapers, active matrix displays, touch screens, EMI shielding, and printable solar cells.

Applications that are compliant with dual reel manufacturing are particularly important. These applications will not involve lithography, vacuum processing, reduced abatement costs, inexpensive substrate processing, and reduced packaging costs. Inkjet printing and gravure printing may be used.

Various embodiments are further described using the following non-limiting working examples.

Working examples

Example 1 synthesis of Ag nanoparticles:

3.34 g of silver acetate and 37.1 g of dodecylamine are dissolved in 400ml of toluene. 1.51 g of sodium borohydride (NaBH)₄) Dissolved in 150ml of water. NaBH was added via dropping funnel over a period of 5 minutes₄The solution was added dropwise to the reaction flask while stirring. The reaction for 2.5 hours was stirred continuously and stopped. The solution was allowed to settle into two phases. The aqueous phase was removed through a separatory funnel, followed by toluene removal from the solution using a rotary evaporator, resulting in a very viscous paste. 250ml of 50/50 methanol/acetone was added to precipitate the Ag nanoparticles. The solution was filtered through a fine sintered glass funnel and the solid product was collected and dried under vacuum at room temperature. 2.3 to 2.5 g of a dark blue solid product are obtained. The nanoparticles have a size of 4nm to 5nm as detected by TEM (fig. 1) and exhibit a sintering or particle fusion temperature of 100 ℃ to 160 ℃ as detected by DSC (fig. 4). Small angle neutron scattering experiments also showed that the silver nanoparticles have a size of 4.6+/-1 nm.

Example 2. synthesis of zinc oxide nanoparticles:

6.3 g of zinc stearate [ Zn (C) ]₁₈H₃₅O₂)₂]And 10 g of hexadecylamine were dissolved in 400ml of toluene. 1.2 grams of potassium hydroxide (KOH) was dissolved in 150ml of water. The KOH solution was added dropwise to the reaction flask via a dropping funnel over a period of 5 minutes while stirring. The reaction was stirred continuously for 2 hours and stopped. The aqueous phase was removed through a separatory funnel, followed by a rotary evaporator to remove toluene from the solution. 250ml of 50/50 methanol/acetone was added to precipitate the zinc oxide nanoparticles. The solution was filtered through a fine sintered glass funnel and the solid product was collected and dried under vacuum at room temperature. About 0.8 g of product was obtained as a white solid. The nanoparticles had a size of about 7.4nm (small fraction of ZnO nanoneedles present) as detected by TEM (fig. 6).

Example 3. coated conductive film from sintered silver nanoparticles:

a cyclohexane solution containing 10 to 20 wt% of Ag nanoparticles synthesized in example 1 was prepared and spin-coated on a clean glass substrate at about 1500 rpm, resulting in a nanoparticle coating film having a thickness of 0.1 to 0.3 μm. The nanoparticle film was heated to a temperature in the range of 90 ℃ to 180 ℃ for 10 minutes while the color of the film changed from dark brown to light silver. The conductivity of the sintered silver film was measured by a four-point probe apparatus. The results are shown in Table 2. It was confirmed that the thin film sintered at the sintering temperature higher than 150 c has excellent conductivity, which reaches about 70% of pure silver.

TABLE 2

Annealing temperature (. degree.C.)	Resistivity (ohm-cm)
		90120150180	1.86 x 10-58.8 x 10-62.4 x 10-62.3 x 10-6

Example 4. form

The morphology of the deposited nanoparticles and sintered film is shown in fig. 7(a) (SEM micrograph of silver nanoparticles with particles of size about 5nm synthesized by the claimed method of the invention (casting the nanoparticles on an aluminum substrate)) and fig. 7(b) (SEM micrograph of silver film on a PET plastic substrate, where the same nanoparticles are cast on the substrate and annealed at a temperature of about 150 ℃). It is shown that the nanoparticles have sintered or fused into a concentrated metal film activated by a processing temperature well below the melting temperature of the material.

Example 5 DSC

In the low-temperature sintering process of the nanoparticles synthesized by the method of the present invention, DSC (differential scanning calorimetry) detects the exothermic process. DSC thermal analysis of the samples was performed using TA Q200 from TAInstructions (New Castle, DE). A sample of approximately 10mg nanoparticles was loaded using an unsealed sample tray. As shown in fig. 4, the DSC thermal analysis curve obtained for a sample of silver nanoparticles synthesized with the method of the present invention having a particle size of about 5nm, when the temperature is raised to 110 ℃ to 160 ℃, demonstrates a unique exothermic process (133 ℃ peak), which is also associated with nanoparticle sintering. The exothermic transition temperature exhibited by DSC also helps determine the most preferred processing temperature for sintering the nanoparticles. In contrast, a sample of silver nanoparticles having a particle size of about 60nm, available from NanoDymics (NDSilver S2-80, Buffalo, NY) did not have an exothermic process (not shown) exhibited at temperatures below 350 ℃. In another preferred embodiment of the present invention, the inorganic nanoparticles synthesized in the method of the present invention exhibit an exothermic sintering process at a temperature of less than 250 ℃.

Additional 103 embodiments include, for example:

1.a method, comprising:

(a) providing a first mixture comprising at least one nanoparticle precursor and at least one first solvent for the nanoparticle precursor, wherein the nanoparticle precursor comprises a cation-containing salt, the cation comprising a metal;

(b) providing a second mixture comprising at least one reactive moiety that reacts with the nanoparticle precursor, and at least one second solvent for the reactive moiety, wherein the second solvent phase separates when the second solvent is mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer, wherein upon combination the first and second mixtures phase separate and form nanoparticles.

2. The method of 1, wherein the first solvent comprises an organic solvent and the second solvent comprises water.

3. The method of 1, wherein the first solvent comprises a hydrocarbon solvent and the second solvent comprises water.

4. The method of 1, wherein the metal comprises a transition metal.

5. The method of 1, wherein the reactive moiety comprises a reducing agent.

6. The method of 1, wherein the reactive moiety comprises a hydride.

7. The method of 1, wherein the reactive moiety comprises a hydroxyl-generating reagent.

8. The method of claim 1, wherein the surface stabilizer, the first solvent, and the second solvent are adapted such that when the first solvent and the second solvent phase separate and form an interface, the surface stabilizer migrates to the interface.

9. The method of 1, wherein the surface stabilizer comprises at least one alkylene group and a nitrogen atom or an oxygen atom.

10. The method of 1, wherein the surface stabilizer comprises at least a substituted amine or a substituted carboxylic acid, wherein the substituent comprises 2 to 30 carbon atoms.

11. The method according to 1, wherein the surface stabilizer comprises an amino compound, a carboxylic acid compound or a thiol compound.

12. The method of 1, wherein the surface stabilizer comprises an amino compound or a carboxylic acid compound.

13. The method of 1, wherein the first mixture comprises the surface stabilizer.

14. The method of 1, wherein the first mixture comprises the surface stabilizer and the second mixture is free of surface stabilizer.

15. The method of 1, wherein the phase separation creates an interface and the nanoparticles form on the interface.

16. The method of 1, further comprising the step of collecting the nanoparticles, wherein the collected nanoparticles have an average particle size of about 1nm to about 20 nm.

17. The method of 1, further comprising the step of collecting the nanoparticles, wherein the collected nanoparticles have an average particle size of about 2nm to about 10nm, and the nanoparticles have a monodispersity that exhibits a standard deviation of 3nm or less.

18. The method according to 1, wherein the nanoparticles can be formed into a film which is electrically conductive due to the material in the nanoparticles, or wherein the nanoparticles can be formed into a semiconducting film which is electrically semiconducting due to the material in the nanoparticles, or wherein the nanoparticles can be formed into an electroluminescent film which is electroluminescent due to the material in the nanoparticles.

19. The method of 1, wherein the volume of the first mixture is greater than the volume of the second mixture.

20. The method of 1, wherein the combining is performed without externally applying heat or cooling.

21. A method, comprising:

(a) providing a first mixture comprising at least one nanoparticle precursor and at least one first solvent for the nanoparticle precursor, wherein the nanoparticle precursor comprises a salt comprising an inorganic cation;

(b) providing a second mixture comprising at least one reactive moiety that reacts with the nanoparticle precursor, and at least one second solvent for the reactive moiety, wherein the second solvent phase separates when the second solvent is mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer, wherein upon combination the first and second mixtures phase separate and form nanoparticles.

22. The method of claim 21, wherein the first solvent comprises an organic solvent and the second solvent comprises water.

23. The method of claim 21, wherein the salt comprises an organic anion.

24. The method of claim 21, wherein the first mixture comprises the surface stabilizer.

25. The method of 21, wherein the combining is performed without applying pressure or vacuum, or without externally applying heat or cooling.

26. The method of 21, wherein the second mixture is added to the first mixture continuously or semi-continuously.

27. The method of 21, further comprising the step of collecting the nanoparticles in a yield of at least 50%.

28. The method of claim 21, the surface stabilizer being represented by the formula:

(R)_nX

wherein R is an alkyl group, n is 1 to 4, and X is a functional group providing Lewis base character.

29. The method of 21, wherein the inorganic cation comprises silver, the reactive moiety is a hydride, the first solvent is an organic solvent, the second solvent is water, and the surface stabilizer is an amine compound.

30. The method of claim 21, wherein the inorganic cation comprises zinc, the reactive moiety is a hydroxyl-generating moiety, the first solvent is an organic solvent, the second solvent is water, and the surface stabilizer is an amine compound.

31. A method, comprising:

(a) providing a first mixture comprising at least one metal-containing nanoparticle precursor, and at least one first solvent;

(b) providing a second mixture comprising at least one moiety that reacts with the nanoparticle precursor, and at least one second solvent, wherein the second solvent phase separates when the second solvent is mixed with the first solvent; wherein the first and the second mixture are provided substantially without the use of a phase transfer catalyst; and

(c) combining the first and second mixtures in the presence of a surface stabilizer, wherein the first and second mixtures phase separate and form nanoparticles.

32. The method of 31, wherein the first mixture and the second mixture are provided without using any phase transfer catalyst.

33. The process according to 31, wherein the phase transfer catalyst is a tetraalkylammonium salt.

34. The method of 31, wherein the first and the second mixtures are provided without using any phase transfer catalyst, and wherein the phase transfer catalyst is a tetraalkylammonium salt.

35. The method of 31, wherein the nanoparticle precursor is dissolved in the first solvent without using any phase transfer catalyst.

36. The method of claim 31, wherein the first solvent is an organic solvent and the second solvent is water.

37. The method of 31, wherein the first solvent is an organic hydrocarbon solvent and the second solvent is water.

38. The method of 31, wherein the nanoparticle precursor does not comprise gold.

39. The method of 31, wherein the surface stabilizer does not comprise a thiol.

40. The method of 31, wherein the nanoparticle precursor does not comprise gold, and wherein the surface stabilizer does not comprise a thiol.

41. A method, comprising:

(a) providing a first mixture comprising at least one nanoparticle precursor, and at least one first solvent,

(b) providing a second mixture comprising at least one moiety that reacts with the nanoparticle precursor, and at least one second solvent, wherein the second solvent phase separates when the second solvent is mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer comprising an amino or carboxylic acid group, wherein the first and second mixtures phase separate and form nanoparticles.

42. The method of 41, wherein the surface stabilizer does not comprise sulfur.

43. The method of 41, wherein the surface stabilizer comprises a C2-C30 substituent bonded to an amino group or a carboxylic acid group.

44. The method of 41, wherein the surface stabilizer comprises an amino group.

45. The method of 41, wherein the surface stabilizer comprises a primary amine.

46. The method of 41, wherein the surface stabilizer comprises an alkylamine.

47. The method of 41, wherein the surface stabilizer comprises a carboxylic acid group.

48. The method of 41, wherein the surface stabilizer comprises a carboxylic acid group linked to an alkyl group.

49. The method of 41, wherein the first solvent is an organic solvent and the second solvent is water.

50. The method of 41, wherein the first solvent is an organic solvent in which the nanoparticle precursor is soluble, and the first mixture is provided without the use of a phase transfer catalyst.

51. A method, comprising:

(a) providing a first mixture comprising at least one first solvent and at least one nanoparticle precursor, wherein the nanoparticle precursor comprises a metal other than gold;

(b) providing a second mixture comprising at least one second solvent and at least one reactive moiety that reacts with the nanoparticle precursor, wherein the second solvent phase separates when the second solvent is mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer, wherein the first and second mixtures phase separate and form nanoparticles.

52. The method of 51, wherein the first solvent is an organic solvent and the second solvent is water.

53. The method of 51, wherein the first mixture is provided substantially without the use of a phase transfer catalyst.

54. The method of 51, wherein the nanoparticle precursor comprises a salt and the cation of the salt comprises a metal.

55. The method of 51, wherein the surface stabilizer comprises an amino compound or a carboxylic acid compound.

56. A method, comprising:

(a) providing a first mixture comprising at least one first solvent and at least one nanoparticle precursor, wherein the nanoparticle precursor comprises a metal;

(b) providing a second mixture comprising at least one second solvent and at least one reactive moiety that reacts with the nanoparticle precursor, wherein the second solvent phase separates when the second solvent is mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer that is not a thiol, wherein the first and second mixtures phase separate and form nanoparticles.

57. The method of 56, wherein the surface stabilizer does not comprise sulfur.

58. The method of 56, wherein the nanoparticle precursor does not comprise gold.

59. The method of 56, wherein the first mixture is provided without using a phase transfer catalyst.

60. The method of 56, wherein the first solvent is an organic solvent and the second solvent is water.

61. A method, comprising:

at least two precursor materials are reacted in the presence of at least one surface stabilizer and two immiscible solvents to form inorganic nanoparticles at an interface of the solvents, wherein a first precursor comprises a metal ion and a second precursor comprises a reducing agent.

62. The method of 61, wherein the nanoparticles comprise a conductive material.

63. The method of 61, wherein the nanoparticles comprise a semiconductive material.

64. The method of 61, wherein the nanoparticles comprise an electroluminescent material.

65. The method of 61, wherein the nanoparticles comprise Ag, Cu, Pt, Pd, Al, Sn, In, Bi, ZnS, ITO, Si, Ge, CdSe, GaAs, SnO₂、WO₃、ZnS:Mn、ZnS:Tb、SrS、SrS:Cs、BaAl₂S₄Or BaAl₂S₄Eu, or a combination thereof.

66. The method of 61, wherein the nanoparticles comprise silver.

67. The method of 61, wherein the nanoparticles have an average particle size of about 1nm to about 1,000 nm.

68. The method of 61, wherein the nanoparticles have an average particle size of about 1nm to about 20 nm.

69. The method of 61, wherein the nanoparticles have an average particle size of about 1nm to about 10 nm.

70. The method of 61, wherein the nanoparticles have a narrow particle size distribution.

71. The method of 61, wherein one of the two immiscible solvents is water.

72. The method of 61, wherein a precursor material is a hydride reducing agent.

73. The method of 61, wherein a precursor material is a hydroxyl generating reagent.

74. The method of 61, wherein the surface stabilizer is an amine or a carboxylic acid.

75. The method of 61, wherein the surface stabilizer is a substituted amine or a substituted carboxylic acid.

76. The method of 61, wherein the surface stabilizer does not comprise sulfur.

77. The method of 61, wherein the surface stabilizer does not comprise a thiol.

78. The process of 61, wherein the reaction is carried out without the use of a phase transfer catalyst.

79. The method of 61, wherein the nanoparticles are surface-coated inorganic nanoparticles that can be processed to form a film at temperatures below 400 ℃.

80. The method of 61, wherein the nanoparticles are surface-coated inorganic nanoparticles that can be processed to form a film at temperatures below 200 ℃.

81. A method consisting essentially of the steps of:

(a) providing a first mixture consisting essentially of at least one nanoparticle precursor and at least one first solvent for the nanoparticle precursor, wherein the nanoparticle precursor consists essentially of a salt comprising a cation comprising a metal;

(b) providing a second mixture consisting essentially of at least one reactive moiety that reacts with the nanoparticle precursor and at least one second solvent for the reactive moiety, wherein the second solvent phase separates when mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer, wherein upon combination the first and second mixtures phase separate and form nanoparticles.

82. The method of 81, wherein the first solvent consists essentially of an organic solvent and the second solvent consists essentially of water.

83. The method of 81, wherein the first mixture is provided without using a phase transfer catalyst.

84. The method of 81, wherein the anion of the salt is metal free.

85. The method of 81, wherein the surface stabilizer consists essentially of at least a substituted amine or a substituted carboxylic acid, wherein the substituent comprises 2 to 30 carbon atoms.

86. The method of 81, wherein the surface stabilizer consists essentially of an amino compound or a carboxylic acid compound.

87. The method of 81, wherein the first mixture consists essentially of the surface stabilizer and the second mixture is free of surface stabilizer.

88. The method of 81, wherein the combining is performed without externally applying heat or cooling.

89. The method of 81, wherein the combining is performed without applying pressure or vacuum.

90. The method of 81, wherein the first mixture and the second mixture are free of compounds that can react with each other to form a sulfide.

91. A composition, comprising:

nanoparticles comprising an amine or carboxylic acid surface stabilizer dispersed in at least one solvent, wherein the concentration of the nanoparticles is from about 1 wt% to about 70 wt%, and the nanoparticles have an average size of from about 1nm to about 20nm and exhibit a monodispersity with a standard deviation of about 3nm or less.

92. The composition of 91, wherein the concentration is about 5% to about 40% by weight.

93. The composition of 91, wherein the solvent is an organic solvent.

94. The composition of 91, wherein the nanoparticles comprise a metal.

95. The composition of 91, wherein the nanoparticles comprise a metal oxide.

96. The composition of 91, wherein the nanoparticles comprise a conductive material.

97. The composition of 91, wherein the nanoparticles comprise a semiconductive material.

98. The composition of 91, wherein the nanoparticles comprise an electroluminescent material.

99. The composition of 91, wherein the nanoparticles have an average particle size of about 1nm to about 20 nm.

100. The composition of 91, wherein the nanoparticles do not comprise gold.

101. A composition comprising metal nanoparticles exhibiting a DSC sintering temperature exotherm peak between about 110 ℃ to about 160 ℃.

102. The composition of 101, wherein the nanoparticles are silver nanoparticles.

103. The composition of 101, wherein the nanoparticles further exhibit a TGA weight loss beginning at about 100 ℃.

This includes 103 embodiments.

Claims (21)

1.A method of preparing nanoparticles, comprising:

(a) providing a first mixture comprising at least one nanoparticle precursor and at least one first solvent for the nanoparticle precursor, wherein the nanoparticle precursor comprises a salt comprising a cation comprising a metal;

(b) providing a second mixture comprising at least one reactive moiety that reacts with the nanoparticle precursor, and at least one second solvent for the reactive moiety, wherein the second solvent phase separates when the second solvent is mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer, wherein upon combination the first and second mixtures phase separate and form nanoparticles having a surface stabilizer layer disposed thereon, and

further comprising the step of collecting the nanoparticles, wherein the collected nanoparticles have an average particle size of 1nm to 100nm, and wherein the thickness of the surface stabilizer layer disposed on the nanoparticles is less than the diameter of the nanoparticles.

2. The method of claim 1, wherein the first solvent comprises an organic solvent and the second solvent comprises water.

3. The method of claim 1, wherein the metal comprises a transition metal.

4. The method of claim 1, wherein the reactive moiety comprises a reducing agent.

5. The method of claim 1, wherein the surface stabilizer comprises at least one alkylene group and a nitrogen atom or an oxygen atom.

6. The method of claim 1, wherein the surface stabilizer comprises an amino compound, a carboxylic acid compound, or a thiol compound.

7. The method of claim 1, wherein the combining is performed without externally applied heat or cooling.

8. A method of preparing nanoparticles, comprising:

(a) providing a first mixture comprising at least one nanoparticle precursor and at least one first solvent for the nanoparticle precursor, wherein the nanoparticle precursor comprises a salt comprising an inorganic cation;

(b) providing a second mixture comprising at least one reactive moiety that reacts with the nanoparticle precursor, and at least one second solvent for the reactive moiety, wherein the second solvent phase separates when the second solvent is mixed with the first solvent; and

(c) combining the first and second mixtures in the presence of a surface stabilizer, wherein upon combination the first and second mixtures phase separate and form nanoparticles having a surface stabilizer layer disposed thereon, and

further comprising the step of collecting the nanoparticles, wherein the collected nanoparticles have an average particle size of 1nm to 100nm, and wherein the thickness of the surface stabilizer layer disposed on the nanoparticles is less than the diameter of the nanoparticles.

9. The method of claim 8, wherein the first solvent comprises an organic solvent and the second solvent comprises water.

10. The method of claim 8, wherein the salt comprises an organic anion.

11. The method of claim 8, wherein the first mixture comprises the surface stabilizer.

12. The method of claim 8, wherein the combining is performed without applying pressure or vacuum, or without externally applying heat or cooling.

13. The method of claim 8, wherein the second mixture is added to the first mixture continuously or semi-continuously.

14. The method of claim 8, further comprising the step of collecting the nanoparticles in a yield of at least 50%.

15. The method of claim 8, the surface stabilizer being represented by the formula:

(R)_nX

wherein R is an alkyl group, n is 1 to 4, and X is a functional group providing Lewis base properties.

16. The method of claim 8, wherein the inorganic cation comprises silver, the reactive moiety is a hydride, the first solvent is an organic solvent, the second solvent is water, and the surface stabilizer is an amine compound.

17. A method of preparing nanoparticles, comprising:

(a) providing a first mixture comprising at least one metal-containing nanoparticle precursor, and at least one first solvent;

(b) providing a second mixture comprising at least one moiety that reacts with the nanoparticle precursor, and at least one second solvent, wherein the second solvent phase separates when the second solvent is mixed with the first solvent; wherein the first and the second mixture are provided without the use of a phase transfer catalyst; and

(c) combining the first and second mixtures in the presence of a surface stabilizer, wherein the first and second mixtures phase separate and form nanoparticles having a surface stabilizer layer disposed thereon, and

further comprising the step of collecting the nanoparticles, wherein the collected nanoparticles have an average particle size of 1nm to 100nm, and wherein the thickness of the surface stabilizer layer disposed on the nanoparticles is less than the diameter of the nanoparticles.

18. The method according to claim 17, wherein the nanoparticle precursor is dissolved in the first solvent without using any phase transfer catalyst.

19. A method of preparing nanoparticles, comprising:

reacting at least two precursor materials in the presence of at least one surface stabilizer and two immiscible solvents to form inorganic nanoparticles having a surface stabilizer layer disposed thereon at an interface of the solvents, wherein a first precursor comprises a metal ion and a second precursor comprises a reducing agent, and

further comprising the step of collecting the nanoparticles, wherein the collected nanoparticles have an average particle size of 1nm to 100nm, and wherein the thickness of the surface stabilizer layer disposed on the nanoparticles is less than the diameter of the nanoparticles.

20. A composition, comprising:

nanoparticles comprising an amine or carboxylic acid surface stabilizer dispersed in at least one solvent, wherein the concentration of the nanoparticles is from 1 to 70 weight percent and the nanoparticles have an average size from 1 to 20nm and exhibit a monodispersity with a standard deviation of 3nm or less, and wherein the thickness of the surface stabilizer layer on the nanoparticles is less than the diameter of the nanoparticles.

21. A composition comprising (i) metal nanoparticles that exhibit a dsc sintering temperature exotherm peak between 110 ℃ and 160 ℃, and (ii) a surface stabilizer layer disposed on the nanoparticles, the surface stabilizer layer having a thickness less than the diameter of the nanoparticles, and wherein the nanoparticles have an average particle size of 1nm to 100 nm.