Molecular dynamics of coalescence and collisions of silver nanoparticles

Guevara-Chapa, Enrique; Mejía-Rosales, Sergio

doi:10.1007/s11051-014-2757-8

Cited by 12 publications

(11 citation statements)

References 18 publications

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“…From the LCTEM data, we hypothesize that each micelle’s internal structure and its orientation at collision, related to possible surface “hot spots” or localized corona inhomogeneities, are important factors that govern micelle fusion and relaxation, and in collisions that do not result in fusion. This morphological and orientational influence on the outcome of collision-and-fusion seems analogous to the importance of the unique crystal structure and lattice-orientation of each particle in metal nanoparticle fusion, where oriented-attachment is well documented, and is known to heavily influence both the coalescence time and the final particle morphology, such as defects, twinning, and surface facets …”

Section: Resultsmentioning

confidence: 75%

“…This morphological and orientational influence on the outcome of collision-andfusion seems analogous to the importance of the unique crystal structure and lattice-orientation of each particle in metal nanoparticle fusion, where oriented-attachment is well documented, and is known to heavily influence both the coalescence time and the final particle morphology, such as defects, twinning, and surface facets. 80 Volume increase (generally ∼15−50%) associated with fusion is found in all of the LCTEM observed micelle fusion events, with the extent of increase varying for each specific event (Table S3 and Figure 3B). This finding indicates that although the total number of BCP chains can be assumed to remain essentially constant before and after collision, the distribution of polymer chains and the volume of internal water, in the postfusion assemblies, have reorganized into morphologies that do not directly mirror either of the prefusion micelles' morphologies, and cannot be modeled in their fusionbehavior as solid, homogeneous droplets or particles according to classical fusion theories.…”

Section: ■ Results and Discussionmentioning

confidence: 92%

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Directly Observing Micelle Fusion and Growth in Solution by Liquid-Cell Transmission Electron Microscopy

et al. 2017

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Amphiphilic small molecules and polymers form commonplace nanoscale macromolecular compartments and bilayers, and as such are truly essential components in all cells and in many cellular processes. The nature of these architectures, including their formation, phase changes, and stimuli-response behaviors, is necessary for the most basic functions of life, and over the past half-century, these natural micellar structures have inspired a vast diversity of industrial products, from biomedicines to detergents, lubricants, and coatings. The importance of these materials and their ubiquity have made them the subject of intense investigation regarding their nanoscale dynamics with increasing interest in obtaining sufficient temporal and spatial resolution to directly observe nanoscale processes. However, the vast majority of experimental methods involve either bulk-averaging techniques including light, neutron, and X-ray scattering, or are static in nature including even the most advanced cryogenic transmission electron microscopy techniques. Here, we employ in situ liquid-cell transmission electron microscopy (LCTEM) to directly observe the evolution of individual amphiphilic block copolymer micellar nanoparticles in solution, in real time with nanometer spatial resolution. These observations, made on a proof-of-concept bioconjugate polymer amphiphile, revealed growth and evolution occurring by unimer addition processes and by particle-particle collision-and-fusion events. The experimental approach, combining direct LCTEM observation, quantitative analysis of LCTEM data, and correlated in silico simulations, provides a unique view of solvated soft matter nanoassemblies as they morph and evolve in time and space, enabling us to capture these phenomena in solution.

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Section: Resultsmentioning

confidence: 75%

Section: ■ Results and Discussionmentioning

confidence: 92%

Directly Observing Micelle Fusion and Growth in Solution by Liquid-Cell Transmission Electron Microscopy

et al. 2017

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“…Despite of successful applications in interpreting a number of experimental measurements, this model suffers from problems caused by its assumptions ignoring the atomistic details of the system. Meanwhile, atomistic simulations have intensively been used to study the sintering [13][14][15] and coalescence [16][17][18][19][20][21] processes in nanomaterial synthesize. Notably, the mechanisms of melting temperature variation and phase transformation have been quantified by Koparde and Cummings [22,23].…”

Section: Introductionsmentioning

confidence: 99%

Size effect on the spontaneous coalescence of nanowires

Yang²,

Wang³

2019

Nanotechnology

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This paper investigates the size effect on the coalescence process of contacting nanoparticles. It is revealed by molecular dynamics that the nanometer-sized surface curvature coupled with the effective melting temperature exhibits a strong influence on the atom diffusion at the interface, and is therefore critical to the coalescence time. This effect is particularly pronouncing for surface curvatures below 20 nm. A phenomenological model is derived from the melting-point reduction approach to describe the kinetic process of nanowire coalescence and is validated against a variety of simulation datasets. The quantitative correlation between the sample size, the sintering temperature and the contact morphology evolution is demonstrated.1 arXiv:1706.08239v2 [cond-mat.mtrl-sci] 10 Apr 2019 INTRODUCTIONSThe spontaneous coalescence is critical for the self-assembly of nanomaterials. It is known to be strongly correlated with the surface atom diffusion, which manifests when the material size goes down below tens of nanometers. Experiments demonstrated significant surface diffusion taking place even at room temperature at sub-10 nm lengthscale [1]. Similar behaviors were reported by experiments of the cold-welding of gold nanowires (NWs) [2] and NPs [3,4], and of self-assembly of nanoparticle (NP) aggregates [5]. Understanding the sizeeffect on the mass-diffusion process at nanoscale solid interfaces is crucial for developing selfassembly technologies of nanostructures, which hold promise for a wide range of applicationsRecently, it is reported by simulations that the coalescence of NPs can start without the thermal activation [7], and that the NP size and the sintering temperature exhibit significant

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“…The MD simulations with classical potentials method is known to be a tool of great reliability in the study of structural evolution and dynamic information of NPs [17][18][19] . In this work, we carried out a comparative study of segregation characteristics of coalescence process between Au and Ni NPs by MD simulations.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Study on Structural and Atomic Evolution Between Au and Ni Nanoparticles Through Coalescence

et al. 2021

Preprint

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Motivated by the structure evolution experiments of Janus NiAu nanoparticles (NPs), we present a detailed study on the thermodynamic evolution of Ni and Au NPs with different ratios of Au and Ni through the molecular dynamics (MD) simulations. It is found that, for fixed Ni particle size (5.8 nm in diameter), the energy variation with the increasing temperature is related to the Au sizes (1.5–9.6 nm in diameter), due to the diverse atomic segregation modes. For a small Au particle, due to lattice induction, the structure will change from order to disorder and then to order. The interface defects of the merging NPs could be automatically eliminated by coalescence processes. The change in energy as the temperature increases is similar to that of monometallic NPs. For larger Au particles, the irregular variation of energy occurs and the atomic energy experience one or two reductions with the increase of the temperature. The segregation of Au atoms to the surface of Ni particle is dominant during the continuous heating process. The coalescence processes of Au atoms strongly determine the final morphology of the particles. Dumbbell-like, Janus and eccentric core-shell spherical structures could be obtained during the heating process. Our results will provide an effective approach to the design of novel materials with specific properties through thermal control.

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Molecular dynamics of coalescence and collisions of silver nanoparticles

Cited by 12 publications

References 18 publications

Directly Observing Micelle Fusion and Growth in Solution by Liquid-Cell Transmission Electron Microscopy

Directly Observing Micelle Fusion and Growth in Solution by Liquid-Cell Transmission Electron Microscopy

Size effect on the spontaneous coalescence of nanowires

Molecular Dynamics Study on Structural and Atomic Evolution Between Au and Ni Nanoparticles Through Coalescence

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