Nanoparticle Interactions Guided by Shape‐Dependent Hydrophobic Forces |
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| Authors: | Shu Fen Tan Sanoj Raj Geeta Bisht Harshini V. Annadata Christian A. Nijhuis Petr Král Utkur Mirsaidov |
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| Affiliation: | 1. Department of Physics, National University of Singapore, Singapore, Singapore;2. Centre for BioImaging Sciences and Department of Biological Sciences, National University of Singapore, Singapore, Singapore;3. Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore;4. Department of Chemistry, University of Illinois at Chicago, Chicago, IL, USA;5. Department of Chemistry, National University of Singapore, Singapore, Singapore;6. NUSNNI‐NanoCore, National University of Singapore, Singapore, Singapore;7. Departments of Physics and Biopharmaceutical Sciences, University of Illinois at Chicago, Chicago, IL, USA |
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| Abstract: | Self‐assembly of solvated nanoparticles (NPs) is governed by numerous competing interactions. However, relatively little is known about the time‐dependent mechanisms through which these interactions enable and guide the nanoparticle self‐assembly process. Here, using in situ transmission electron microscopy imaging combined with atomistic modeling, it is shown that the forces governing the self‐assembly of hydrophobic nanoparticles change with the nanoparticle shapes. By comparing how gold nanospheres, nanocubes, nanorods, and nanobipyramids assemble, it is shown that the strength of the hydrophobic interactions depends on the overlap of the hydrophobic regions of the interacting nanoparticle surfaces determined by the nanoparticle shapes. Specifically, this study reveals that, in contrast to spherical nanoparticles, where van der Waals forces play an important role, hydrophobic interactions can be more relevant for nanocubes with flat side faces, where an oriented attachment between the nanocubes is promoted by these interactions. The attachment of nanocubes is observed to proceed in two distinct pathways: nanocubes either: (i) prealign their faces before the attachment, or (ii) first connect through a misaligned (edge‐to‐edge) attachment, followed by a postattachment alignment of their faces. These results have important implications for understanding the interaction dynamics of NPs and provide the framework for the design of future self‐assembled nanomaterials. |
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| Keywords: | hydrophobic interactions in situ transmission electron microscopy nanoparticles self‐assembly van der Waals forces |
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