Method of making monodisperse nanoparticles
A method of making particles of either spherical or cylindrical geometry with a characteristic diameter less than 50 nanometers by mixing at least one structure directing agent dissolved in a solvent with at least one amphiphilic block copolymer dissolved in a solvent to make a solution containing particles, where the particles can be subsequently separated and dispersed in a solvent of choice.
1. A method of making particles, comprising mixing at least one structure directing agent dissolved in a first solvent with at least one amphiphilic block copolymer dissolved in a second solvent to make a solution containing particles with a characteristic diameter less than 50 nanometers.
2. The method of claim 1 wherein said particles are monodisperse with a standard deviation of less than 15% around said characteristic diameter.
3. The method of claim 1 wherein said mixing occurs at a temperature greater than 50° C.
4. The method of claim 1 wherein said mixing occurs at a temperature less than 80° C.
5. The method of claim 1 wherein said particles are separated and then dispersed into a third solvent.
6. The method of claim 1 wherein said amphiphilic block copolymer is selected from the group consisting of polystyrene-b-polyvinylpyridine (PS-PVP), poly(isoprene)-poly(vinyl pyridine), poly(vinyl pyridine)-poly(styrene)-poly(vinyl pyridine), poly(styrene)-polyvinyl pyridine)-poly(styrene), poly(styrene-poly(acrylic acid), poly(styrene)-poly(butadiene)-poly(vinyl pyridine), poly(styrene-poly(methacrylic acid), poly(styrene)-poly(ethylene oxide), poly(butadiene)-poly(acrylic acid), poly(butadiene)-poly(ethylene oxide), poly(vinyl pyridine)-poly(butadiene)-poly(vinyl pyridine), poly(ethylene)-poly(ethylene oxide), and poly(styrene)-poly(vinyl pyridine)-poly(ethylene oxide).
7. The method of claim 1 wherein said structure directing agent is selected from the group consisting of 8,13-bis(1-hydroxyethyl)-3,7,12,17-tetramethyl-21H,23H-porphine-2,18-dipropionic acid, 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine, tetra(4-carboxyphenyl)porphine (TCP), 2-(4′-hydroxybenzeneazo)benzoic acid, hydrophilic dye molecules, such as fluorescein, small protein molecules, small peptide molecules, inorganic salts, and hydrophilic nanoparticles.
8. The method of claim 7 wherein said inorganic salts have the formula M(NO 3 ) 3 , where M is selected from the group consisting of Eu, Pr, Tb, Er, Tm, Ce, Fe, and ZnNO 3 .
9. The method of claim 1 wherein said first solvent and said second solvent are selected from the group consisting of dioxane, toluene, tetrahydrofuran and dimethylfuran.
10. The method of claim 1 wherein said third solvent is selected from the group consisting of toluene, dioxane and chloroform.
11. The method of claim 1 wherein the amphiphilic block copolymer comprises a hydrophilic block copolymer and a hydrophobic block copolymer.
12. The method of claim 11 wherein said hydrophilic block copolymer should have a molecular weight sufficiently large such that micelle formation occurs.
13. The method of claim 12 wherein said hydrophilic block copolymer comprises polyvinylpyridine with a molecular weight greater than approximately 10,000.
14. The method of claim 13 wherein said molecular weight is less than approximately 30,000 to form particles with a spherical geometry.
15. The method of claim 12 wherein said hydrophilic block copolymer comprises polyvinylpyridine with a molecular weight greater than approximately 40,000 to form particles with a cylindrical geometry.
16. The method of claim 11 wherein said characteristic dimension is changed by changing the molar ratio of hydrophilic block copolymer to said hydrophobic block copolymer.
17. The method of claim 1 wherein said solution is placed on a substrate, said solution containing particles and a liquid portion, said liquid portion evaporated to form a continuous film of ordered polymer particles on said substrate.
18. A method of making hollow particles, comprising mixing at least one alcohol-soluble structure directing agent dissolved in a first solvent with at least one amphiphilic block copolymer dissolved in a second solvent to make a solution; and removing said at least one alcohol-soluble structure directing agent with an alcohol wash to form hollow particles with a characteristic diameter less than 50 nanometers.
19. The method of claim 18 wherein said alcohol-soluble structure directing agent is 2-(4′-hydroxybenzeneazo)benzoic acid.
20. A method of making particles containing an inorganic component, comprising mixing a first solution comprising a metal precursor compound selected from an Au compound, a Pt compound, a Pd compound, a Ag compound and a M(NO 3 ) 3 .5H 2 O compound dissolved in a first solvent, where M is selected from Eu, Pr, Tb, Er, Tm, Ce, Fe, and ZnNO 3 , with a second solution of an amphiphilic block copolymer dissolved in a second solvent at an elevated temperature to make particles with a characteristic dimension of less than 50 nanometers.