(484e) Implicit Solvent Model for the Interfacial Configuration of Colloidal Nanoparticles and Application to the Self-Assembly of Truncated Cubes

This study outlines the development of an implicit solvent model that reproduces the behavior of colloidal nanoparticles at a fluid-fluid interface. The center-point of this formulation is the generalized Quaternion-based Orientational Constraint (QOCO) method. The model captures 3 major energetic characteristics that define the nanoparticle configuration – position (orthogonal to the interfacial plane), orientation, and inter-nanoparticle interaction. The framework encodes physically relevant parameters that provide an intuitive means to simulate a broad spectrum of interfacial conditions. Results show that for a wide range of shapes, we are able to replicate the behavior of an isolated nanoparticle at an explicit fluid-fluid interface, both qualitatively and quantitatively. Furthermore, the family of truncated cubes is used as testbed to analyze the effect of changes in the degree of truncation on the potential-of-mean-force landscape.

Thereafter, a large number of nanoparticles are simulated in a molecular dynamics setting, using coarse-grained polybead nanoparticles^[1],[2]. In agreement with experiments^[2]-[7], we observe the formation of bilayer honeycomb and monolayer square lattices. Finally, by exploring a broader range of interfacial conditions, we identify and suggest the assembly mechanism for a set of novel superlattice configurations.

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[4] W. H. Evers, B. Goris, S. Bals, M. Casavola, J. de Graaf, R. V. Roij, M. Dijkstra, and D. Vanmaekelbergh, “Low-Dimensional Semiconductor Superlattices Formed by Geometric Control over Nanocrystal Attachment,” Nano Lett., vol. 13, no. 6, pp. 2317–2323, Jun. 2013.

[5] M. P. Boneschanscher, W. H. Evers, J. J. Geuchies, T. Altantzis, B. Goris, F. T. Rabouw, S. A. P. van Rossum, H. S. J. van der Zant, L. D. A. Siebbeles, G. Van Tendeloo, I. Swart, J. Hilhorst, A. V. Petukhov, S. Bals, and D. Vanmaekelbergh, “Long-range orientation and atomic attachment of nanocrystals in 2D honeycomb superlattices,” Science, vol. 344, no. 6190, pp. 1377–1380, Jun. 2014.

[6] C. van Overbeek, J. L. Peters, S. A. P. van Rossum, M. Smits, M. A. van Huis, and D. Vanmaekelbergh, “Interfacial Self-Assembly and Oriented Attachment in the Family of PbX (X = S, Se, Te) Nanocrystals,” J. Phys. Chem. C, vol. 122, no. 23, pp. 12464–12473, May 2018.

[7] J. L. Peters, T. Altantzis, I. Lobato, M. A. Jazi, C. van Overbeek, S. Bals, D. Vanmaekelbergh, and S. B. Sinai, “Mono- and Multilayer Silicene-Type Honeycomb Lattices by Oriented Attachment of PbSe Nanocrystals: Synthesis, Structural Characterization, and Analysis of the Disorder,” Chemistry of Materials, vol. 30, no. 14, pp. 4831–4837, Jul. 2018.