Self assembled organic nanocrystal superlattices
View Patent ↗A process for the preparation of a self assembled superlattice thin film of organic nanocrystal particles is described comprising: (i) combining one or more functional organic material to be precipitated as nanocrystal particles and one or more surface active material in a compressed CO 2 phase with a density of at least 0.1 g/cc, where the functional material is substantially insoluble in the compressed CO 2 in the absence of the surfactant, the surfactant comprises a compressed CO 2 -philic portion and a functional material-philic portion, and the compressed CO 2 phase, functional material and surfactant interact to form an aggregated system having a continuous compressed CO 2 phase and a plurality of aggregates comprising surfactant and functional material molecules of average diameter less than 50 nanometers dispersed therein; (ii) rapidly depressurizing the compressed CO 2 phase thereby precipitating the dispersed functional and surfactant materials in the form of composite organic nanocrystals of average diameter less than 50 nanometers, and (iii) depositing the organic nanocrystals on a substrate surface, wherein the organic nanocrystals form a thin film having an ionic content of less than 0.001 M in equivalent sodium chloride concentration on the substrate surface, and the thin film exhibits a long range periodicity in the arrangement of the organic nanocrystals in a self assembled superlattice structure, as evidenced by x-ray diffraction.
1. A process for the preparation of a self assembled superlattice thin film of organic nanocrystal particles comprising:
(i) combining one or more functional organic material to be precipitated as nanocrystal particles and one or more surface active material in a compressed CO 2 phase with a density of at least 0.1 g/cc, where the functional material is substantially insoluble in the compressed CO 2 in the absence of the surfactant, the surfactant comprises a compressed CO 2 -philic portion and a functional material-philic portion, and the compressed CO 2 phase, functional material and surfactant interact to form an aggregated system having a continuous compressed CO 2 phase and a plurality of aggregates comprising surfactant and functional material molecules of average diameter less than 50 nanometers dispersed therein;
(ii) rapidly depressurizing the compressed CO 2 phase thereby precipitating the dispersed functional and surfactant materials in the form of composite organic nanocrystals of average diameter less than 50 nanometers; and
(iii) depositing the organic nanocrystals on a substrate surface, wherein the organic nanocrystals form a thin film having an ionic content of less than 0.001 M in equivalent sodium chloride concentration on the substrate surface, and the thin film exhibits a long range periodicity in the arrangement of the organic nanocrystals in a self assembled superlattice structure, as evidenced by x-ray diffraction.
2. A process according to claim 1 , where the molar ratio of the surfactant to the functional material is at least 1:1.
3. A process according to claim 1 , where the molar ratio of the surfactant to the functional material is at least 10:1.
4. A process according to claim 1 , wherein the compressed carbon dioxide is a supercritical fluid.
5. A process according to claim 1 , wherein the functional and surfactant materials are precipitated in the form of composite particles of average diameter from 0.5 to 10 nanometers.
6. A process according to claim 1 , wherein the functional organic material comprises a pure organic compound.
7. A process according to claim 1 , wherein the functional organic material comprises a metallo-organic compound.
8. A process according to claim 1 , wherein the functional material-philic portion of the surfactant comprises a CO 2 -phobic portion.
9. A process according to claim 8 , wherein the surfactant is a fluorinated, perfluoropolyether, or siloxane surfactant having a CO 2 -philic portion and a CO 2 -phobic portion.
10. A process according to claim 1 , wherein the ratio of compressed carbon dioxide to functional material is from about 100,000:1 to about 1:1.
11. A process according to claim 1 , wherein the thin film formed in step (iii) has a thickness of less than 10 micrometers.
12. A process according to claim 1 , wherein the thin film formed in step (iii) has a thickness of less than 1 micrometer.
13. A process according to claim 1 , wherein the thin film formed in step (iii) has a thickness of less than 0.1 micrometers.
14. A process according to claim 1 , wherein d-spacing of the self-assembled structure ranges from 0.5 nm to 100 nm.
15. A process according to claim 1 , wherein d-spacing of the self-assembled structure ranges from 0.5 nm to 10 nm.
16. A thin film obtained from the process of claim 1 comprising a self assembled superlattice of functional organic material nanocrystal particles.
17. A thin film according to claim 16 , wherein the functional organic material comprises a pure organic compound.
18. A thin film according to claim 16 , wherein the functional organic material comprises a metallo-organic compound.
19. A thin film according to claim 16 , having a thickness of less than 10 micrometers, and wherein d-spacing of the self-assembled structure ranges from 0.5 nm to 100 nm.
20. A thin film according to claim 16 , having a thickness of less than 1 micrometer, and wherein d-spacing of the self-assembled structure ranges from 0.5 nm to 10 nm.