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Volumn 316, Issue 5822, 2007, Pages 261-264

Plastic and moldable metals by self-assembly of sticky nanoparticle aggregates

Author keywords

[No Author keywords available]

Indexed keywords

DITHIOL DERIVATIVE; METAL; NANOMATERIAL; NANOPARTICLE;

EID: 34247340971     PISSN: 00368075     EISSN: 10959203     Source Type: Journal    
DOI: 10.1126/science.1139131     Document Type: Article
Times cited : (253)

References (25)
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    • A. M. Kalsin et al., Science 312, 420 (2006).
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    • BT), and the nanoparticles would clump even in the absence of irradiation. Indeed, we verified experimentally that without excess DDA and DDAB, the nanoparticle solutions are unstable and precipitate rapidly to give disordered, black-powder aggregates.
    • BT), and the nanoparticles would clump even in the absence of irradiation. Indeed, we verified experimentally that without excess DDA and DDAB, the nanoparticle solutions are unstable and precipitate rapidly to give disordered, black-powder aggregates.
  • 11
    • 34247400514 scopus 로고    scopus 로고
    • Low-power irradiation for periods of up to several tens of minutes did not cause desorption of the thiols from nanoparticle surfaces. With more intense sources of UV light (>50 mW/cm2) or at elevated temperatures, however, desorption was observed, and the nanoparticles coalesced into larger particles and aggregates that precipitated from solution
    • 2) or at elevated temperatures, however, desorption was observed, and the nanoparticles coalesced into larger particles and aggregates that precipitated from solution.
  • 13
    • 34247359767 scopus 로고    scopus 로고
    • The nucleation-and-growth mechanism applies to this system only at short time scales, during which the supraspheres assemble by means of dipole-dipole interactions to consume all free nanoparticles in solution. At longer time scales, the suprasphere aggregates become cemented by dithiol cross-links and cannot coalesce with one another to achieve full phase separation.
    • The nucleation-and-growth mechanism applies to this system only at short time scales, during which the supraspheres assemble by means of dipole-dipole interactions to consume all free nanoparticles in solution. At longer time scales, the suprasphere aggregates become "cemented" by dithiol cross-links and cannot coalesce with one another to achieve full phase separation.
  • 14
    • 34247359328 scopus 로고    scopus 로고
    • -1/3.
    • -1/3.
  • 16
    • 34247335678 scopus 로고    scopus 로고
    • Light-controlled self-assembly gave supraspheres of smaller size dispersity than alternative methods described in the literature (7-9). Also, we verified that spheres connected by shorter dithiol ligands were less sticky and required prolonged heating at high temperatures in order to self-assemble into larger structures. These properties made such supraspheres unsuitable for the molding experiments we conducted.
    • Light-controlled self-assembly gave supraspheres of smaller size dispersity than alternative methods described in the literature (7-9). Also, we verified that spheres connected by shorter dithiol ligands were less "sticky" and required prolonged heating at high temperatures in order to self-assemble into larger structures. These properties made such supraspheres unsuitable for the molding experiments we conducted.
  • 17
    • 34247391332 scopus 로고    scopus 로고
    • Metal weight percent was estimated from that of underlying gold nanoparticles. Specifically, for a spherical core-shell nanoparticle with a core of radius Rc ∼ 2.8 nm and density ρc, 19.3 g/cm3 (for gold) and with a self-assembled monolayer (SAM) of thickness ∼1.4 nm and density ρSAM ∼ 0.73 (for linear hydrocarbons, the weight percentage of metal may be estimated as ρcRc3/[ρ cRc3, ρSAMR SAM3- Rc3 ∼ 0.92. Similar values are expected for other noble metals
    • 3 ∼ 0.92. Similar values are expected for other noble metals.
  • 19
    • 34247343498 scopus 로고    scopus 로고
    • When nanoparticles were simply cross-linked without forming the intermediate supraspheres, they formed precipitates that could not be assembled, molded, or hardened.
    • When nanoparticles were simply cross-linked without forming the intermediate supraspheres, they formed precipitates that could not be assembled, molded, or hardened.
  • 22
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    • 6 V/m [e.g., (23)].
    • 6 V/m [e.g., (23)].
  • 25
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    • We thank M. Ratner and G. C. Schatz for helpful discussions, as well as S. Smoukov for his help with nanoindentation experiments. This work was supported by the NSF CAREER (CTS-0547633) Award, 3M Non-Tenured Faculty Award, the Pew Scholarship, and the Sloan Fellowship to B.A.G, R.K. was supported by the N5F under the Northwestern Materials Research Science and Engineering Center Award. K.J.M.B. was supported by the NSF Graduate Fellowship. C.J.C. was supported by a Northwestern University Presidential Fellowship
    • We thank M. Ratner and G. C. Schatz for helpful discussions, as well as S. Smoukov for his help with nanoindentation experiments. This work was supported by the NSF CAREER (CTS-0547633) Award, 3M Non-Tenured Faculty Award, the Pew Scholarship, and the Sloan Fellowship (to B.A.G.). R.K. was supported by the N5F under the Northwestern Materials Research Science and Engineering Center Award. K.J.M.B. was supported by the NSF Graduate Fellowship. C.J.C. was supported by a Northwestern University Presidential Fellowship.


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