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Volumn 312, Issue 5772, 2006, Pages 420-424

Electrostatic self-assembly of binary nanoparticle crystals with a diamond-like lattice

Author keywords

[No Author keywords available]

Indexed keywords

CRYSTAL LATTICES; CRYSTAL STRUCTURE; DIAMONDS; ELECTROSTATICS; GOLD; SELF ASSEMBLY; SILVER;

EID: 33645989760     PISSN: 00368075     EISSN: 10959203     Source Type: Journal    
DOI: 10.1126/science.1125124     Document Type: Article
Times cited : (845)

References (40)
  • 9
  • 12
    • 33645962689 scopus 로고    scopus 로고
    • note
    • For crystals composed of Ag and Au nanoparticles, the lattice is isostructural with sphalerite ZnS (SG 216). For crystals made of only one type of metal cores (compare Fig. 5B), the lattice is best described as diamond (SG 227). To account for both of these possibilities we use "diamond-like" nomenclature in the text.
  • 15
    • 33646003122 scopus 로고    scopus 로고
    • note
    • Supporting material is available on Science Online.
  • 17
    • 33645960305 scopus 로고    scopus 로고
    • note
    • After the evaporation of the "good" solvent, the NP crystals constituted only ∼0.01% v/v of the remaining solution, so crystallization cannot be attributed to confinement effects that might have been operative had all liquid been evaporated.
  • 19
    • 33645977361 scopus 로고    scopus 로고
    • note
    • -1 ∼ 2.7 nm. We emphasize that this number can only be treated as an estimate, because with NPs several nanometers in diameter, we are at the limit of applicability of the DLVO mean-field approach. At the same time, our approximation is qualitatively correct as verified by recent numerical Monte Carlo simulations of pairs of nanometer-sized charged particles (20).
  • 25
    • 33646002833 scopus 로고    scopus 로고
    • note
    • 2 group (26, 27). TEM images of the charged NPs that we used reveal that the SAMs are "rigid" (i.e., their thicknesses between aggregated NPs are the same as those on isolated ones) and that no interpenetration takes place. This observation is easily rationalized by noting that possible interpenetration of the alkyl chains would have to take place at the expense of favorable electrostatic interactions between oppositely charged head groups. Overall, the van der Waals forces in our system can be neglected even if two NPs touch each other. At such small separations, the interactions are dominated by attractive electrostatic forces. Finally, we note that entropic forces due to SAM squeezing (28) are also negligible, because the SAMs are not "compressible."
  • 29
    • 33645973100 scopus 로고    scopus 로고
    • note
    • Results of recent molecular dynamics simulations (21) indicate that mean-field screening concepts can be extended to the nanoscale and can be used to approximate electrostatic forces acting between nanoparticles screened by counterions comparable in size (within one order of magnitude) and present in small quantities (a few layers). Although quantitative analogies could thus be justified, we restrict our discussion to qualitative arguments that are sufficient to explain experimental observations.
  • 40
    • 33645992629 scopus 로고    scopus 로고
    • note
    • We thank J.-G. Zheng and M. Kowski for helpful discussions. B.A.G. gratefully acknowledges financial support from the Camille and Henry Dreyfus New Faculty Awards Program, NSF (grant 0503673), and the American Chemical Society Petroleum Research Fund (Award 42953-ACS). K.J.M.B. was supported by the NSF Graduate Fellowship.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.