Interactions between sterically stabilized nanoparticles in supercritical fluids: A simulation study

Patel, Nikhil; Егоров, С. А.

doi:10.1063/1.2434155

Cited by 45 publications

(70 citation statements)

References 26 publications

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“…[18][19][20][21] It is important to note that the effective NC-NC interactions in a solvent are very different from the ones in vacuum due to solvent-capping layer interactions. The work of Patel and Egorov 22 focused on the PMF for very small capped NC cores ͑Au 38 ͒ for varying solvent quality, and it was found that the PMF can be tuned from strongly attractive to fully repulsive. In our previous work, we have shown for one system that the interaction between alkylthiol capped NCs becomes purely repulsive in a good solvent ͑n-hexane͒; 23 we are currently investigating in detail the NC-NC interactions in different solvents at different conditions.…”

Section: Introductionmentioning

confidence: 99%

Understanding interactions between capped nanocrystals: Three-body and chain packing effects

Schapotschnikow

Vlugt

2009

The Journal of Chemical Physics

152

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Self-assembly of capped nanocrystals ͑NC͒ attracted a lot of attention over the past decade. Despite progress in manufacturing of NC superstructures, the current understanding of their mechanical and thermodynamic stability is still limited. For further applications, it is crucial to find the origin and the magnitude of the interactions that keep self-assembled NCs together, and it is desirable to find a way to rationally manipulate these interactions. We report on molecular simulations of interacting gold NCs protected by capping molecules. We computed the potential of mean force for pairs and triplets of NCs of different size ͑1.8-3.7 nm͒ with varying ligand length ͑ethanethiol-dodecanethiol͒ in vacuum. Pair interactions are strongly attractive due to attractive van der Waals interactions between ligand molecules. Three-body interaction results in an energy penalty when the capping layers overlap pairwise. This effect contributes up to 20% to the total energy for short ligands. For longer ligands, the three-body effects are so large that formation of NC chains becomes energetically more favorable than close packing of capped NCs at low concentrations, in line with experimental observations. To explain the equilibrium distance for two or more NCs, the overlap cone model is introduced. This model is based on relatively simple ligand packing arguments. In particular, it can correctly explain why the equilibrium distance for a pair of capped NCs is always Ϸ1.25 times the core diameter independently on the ligand length, as found in our previous work ͓Schapotschnikow, R. Pool, and T. J. H. Vlugt, Nano Lett. 8, 2930 ͑2008͔͒. We make predictions for which ligands capped NCs self-assemble into highly stable three-dimensional structures, and for which they form high-quality monolayers.

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Section: Introductionmentioning

confidence: 99%

Understanding interactions between capped nanocrystals: Three-body and chain packing effects

Schapotschnikow

Vlugt

2009

The Journal of Chemical Physics

152

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“…As the nanoparticles approach closer, chains enter the region between particles and align into blocks on each nanoparticle and then lie parallel to those on opposite nanoparticles, making an extended ordered block. There appears to be little apparent interdigitation of individual chains from opposite nanoclusters as was reported by Patel & Egorov (2007). At the short end of this range (approx.…”

Section: (A) Qualitative Descriptionmentioning

confidence: 54%

“…As the nanoparticles approach more closely, chains from opposite particles move into the inter-particle region. Patel & Egorov (2007) describe the interaction between opposing chains as interdigitation. However, the behaviour we observe is not well described by this term; we observe a lateral co-alignment of the aligned blocks on opposing nanoparticles (figure 1d).…”

Section: Discussionmentioning

confidence: 99%

“…Egorov (2005) devised a model for the nanoparticle interaction based on the classical density functional theory and Patel & Egorov (2007) performed molecular dynamics simulations similar in character to those presented there. Schapotschnikow et al (2007aSchapotschnikow et al ( ,b, 2008, Schapotschnikow & Vlugt (2009) and Pool et al (2007) have completed a comprehensive series of simulation studies, including a study of nanoparticle interactions (Schapotschnikow & Vlugt 2009), that is also highly relevant.…”

Section: Introductionmentioning

confidence: 99%

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A computer simulation study of the interaction between passivated and bare gold nanoclusters

et al. 2011

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Molecular dynamics simulations have been performed with the objective of understanding the phenomenon of nanoparticle aggregation. We have attempted to calculate the free energy associated with the interaction between two 38-atom gold nanocores, with attached passivating thiol chains, in a supercritical ethane solvent and in the vacuum, and without passivating chains in ethane at the critical density and twice the critical density. Our model differs from those used by others in that each gold nanocore is bound by a realistic metal potential that is not formally rigid. In the case of the passivated nanoparticles, we observe profound structural changes in the nanocores, which radically affect the nature of the interaction between them-to the extent that fusion of the two gold nanocores cannot be prevented under the conditions examined. Bare nanocores, on the other hand, do not exhibit much structural change until close contact occurs. The fused nanocores in the passivated and bare nanocore systems have significantly different morphologies. There is evidence that at higher solvent density, the interaction between bare nanocores is slightly repulsive.

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“…[15][16][17][18][19] Due to high computational cost, only few studies investigated properties of systems with several NCs. 16,20,21 The NCs in those studies were relatively small (up to 140 atoms) compared to the ones typically used in assembly experiments. 12 Recent simulation studies 19,21 show, in addition, that the presence of solvent strongly influences the structure of capping layers.…”

Section: 13mentioning

confidence: 99%

Coarse-grained model for gold nanocrystals with an organic capping layer

Schapotschnikow¹,

Pool²,

Vlugt³

2007

Molecular Physics

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Interactions between sterically stabilized nanoparticles in supercritical fluids: A simulation study

Cited by 45 publications

References 26 publications

Understanding interactions between capped nanocrystals: Three-body and chain packing effects

Understanding interactions between capped nanocrystals: Three-body and chain packing effects

A computer simulation study of the interaction between passivated and bare gold nanoclusters

Coarse-grained model for gold nanocrystals with an organic capping layer

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