Methods for dissolving droplet particle assembly with co-solvent, and particle assemblies obtained therefrom
Some variations provide a method of assembling a plurality of particles into particle assemblies, comprising: (a) obtaining a first fluid containing particles and a solvent for the particles; (b) obtaining a second fluid not fully miscible with the first fluid; (c) obtaining a third fluid that is a co-solvent for the first fluid and the second fluid; (d) combining the first fluid and the second fluid to generate an emulsion containing droplets of the first fluid in the second fluid; (e) adding the third fluid to the emulsion; and (f) dissolving out the solvent from the droplets into the third fluid, thereby forming particle assemblies. Some variations also provide an assembly of nanoparticles, wherein the assembly has a volume from 1 μm 3 to 1 mm 3 , a packing fraction from 20% to 100%, and/or an average relative surface roughness less than 1%, wherein the assembly is not disposed on a substrate.
1. A method of assembling a plurality of particles into particle assemblies, said method comprising:
(a) obtaining a first fluid containing particles and a solvent for said particles;
(b) obtaining a second fluid, wherein said first fluid is not fully miscible in said second fluid;
(c) obtaining a third fluid that is a co-solvent for said first fluid and said second fluid;
(d) combining said first fluid and said second fluid to generate an emulsion containing a dispersed phase of droplets of said first fluid in said second fluid;
(e) adding said third fluid to said emulsion; and
(f) dissolving said solvent from said droplets into a mixture of said second fluid and said third fluid, thereby forming particle assemblies.
2. The method of claim 1 , wherein said particles are present in said first fluid in a concentration from about 1 mg/mL to about 100 mg/mL.
3. The method of claim 1 , wherein said first fluid has a solubility in said second fluid from about 0.01 vol % to about 20 vol %.
4. The method of claim 1 , wherein said first fluid has a solubility in said third fluid from about 1 vol % to about 100 vol % (completely miscible).
5. The method of claim 1 , wherein said second fluid has a solubility in said third fluid from about 10 vol % to about 100 vol % (completely miscible).
6. The method of claim 1 , wherein said solvent in said first fluid is selected from the group consisting of water, dimethyl formamide, diethyl formamide, acetonitrile, dimethyl sulfoxide, methanol, ethanol, isopropanol, 1-propanol, isobutanol, 1-butanol, 2-butanol, t-butanol, acetone, tetrahydrofuran, and combinations thereof.
7. The method of claim 1 , wherein said second fluid is selected from the group consisting of methyl laurate, 1-butanol, t-butanol, 1-octanol, 1-hexanol, 1-decanol, ethyl ether, dibutyl ether, dihexyl ether, dioctyl ether, methyl t-butyl ether, methyl ethyl ketone, cyclohexane, ethyl acetate, and combinations thereof.
8. The method of claim 1 , wherein said third fluid is selected from the group consisting of 1-octanol, 1-butanol, t-butanol, 1-hexanol, 1-decanol, ethyl ether, dibutyl ether, dihexyl ether, dioctyl ether, methyl t-butyl ether, methyl ethyl ketone, cyclohexane, ethyl acetate, and combinations thereof.
9. The method of claim 1 , wherein an interface-stabilization substance is contained within said first fluid and/or said second fluid.
10. The method of claim 1 , wherein said particles contain a starting ligand, and wherein said particles are ligand-exchanged to render said particles soluble in said first fluid, before or during step (a).
11. The method of claim 10 , wherein said particles are ligand-exchanged to replace said starting ligand with an inorganic ligand selected from the group consisting of thiocyanate, borofluoride, hexafluorophosphate, and combinations thereof.
12. The method of claim 1 , said method further comprising adjusting pH of said first fluid, prior to step (d).
13. The method of claim 1 , wherein step (d) includes a step selected from the group consisting of vortex mixing, ultrasonic mixing, impeller mixing, microfluidizing, microfluidics droplet generation, porous-glass droplet generation, and combinations thereof.
14. The method of claim 1 , wherein in step (f), said droplets are agitated.
15. The method of claim 1 , wherein step (f) is conducted for a dissolving time from about 1 second to about 10 hours.
16. The method of claim 1 , wherein step (f) is conducted at a dissolving temperature from about 15° C. to about 150° C.
17. The method of claim 1 , wherein steps (d), (e), and (f) are continuous.
18. The method of claim 1 , wherein steps (d), (e), and (f) are conducted in batch.
19. The method of claim 1 , wherein in step (f), the number of said particle assemblies equals the number of said droplets.
20. The method of claim 1 , wherein in step (f), the number of said particle assemblies is less than the number of said droplets.
21. An assembly of nanoparticles, wherein said assembly has a volume from 1 μm 3 to 1 mm 3 , a packing fraction from 20% to 100%, and an average relative surface roughness less than 5%, wherein said average relative surface roughness is calculated as a ratio of size of an assembly-surface protrusion to the diameter of said assembly, averaged across the entire surface of said assembly, wherein said assembly is spherical, and wherein said assembly is not disposed on a substrate.
22. The assembly of claim 21 , wherein said packing fraction is at least 90%.
23. The assembly of claim 21 , wherein said average relative surface roughness is less than 0.1%.
24. The assembly of claim 21 , wherein said assembly is a core-shell assembly.
25. The assembly of claim 21 , wherein said assembly contains a material selected from the group consisting of metals, metal oxides, metal fluorides, metal sulfides, metal phosphides, ceramics, glasses, polymers, and combinations thereof.
26. The assembly of claim 21 , wherein said assembly is free of organic ligands.
27. The assembly of claim 21 , wherein said assembly consists essentially of lead(II) sulfide nanoparticles.