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Colloidal open crystals — sparsely populated periodic structures, comprising low-coordinated colloidal particles — are attractive targets for self-assembly because of their variety of applications, for example, as photonic materials, phononic and mechanical metamaterials, as well as porous media [1-4]. Colloidal particles in their primitive form offer short-range isotropic interactions and thus tend to form close-packed crystals. Despite remarkable advances over the last two decades in the synthesis of colloidal particles, endowed with anisotropic and/or specific interactions [5-7], programming self-assembly of colloidal particles into open crystals has proved elusive. In this presentation, I will first discuss a series of computational studies that establish facile bottom-up routes for rationally designed patchy particles to self-assemble into a variety of colloidal open crystals, especially those much sought after as photonic crystals [8-12]. The strategies include encoding hierarchical self-assembly pathways and ring size selection, in close connection with advances in colloid synthesis. I will also discuss how hierarchical self-assembly of designer patchy particles can instead be exploited to develop a colloidal model of water – a classic example of an empty liquid [13]. I will demonstrate how this colloidal model unravels a novel topological distinction between the two liquids of different densities involved in the liquid-liquid phase transition (LLPT) [13] – originally hypothesised in connection with the host of anomalous thermodynamic properties in water [14]. Finally, I will illustrate how entanglement can emerge as a general mechanism for densification by uncovering a hierarchy of topological transitions in a network liquid that densifies via two successive LLPTs [15]. References [1] X. Mao, Q. Chen and S. Granick, Nat. Mater. 2013, 12, 217. [2] J. D. Joannopoulos, P. R. Villeneuve and S. Fan, Nature, 1997, 386, 143. [3] K. Aryana and M. B. Zanjani, J. Appl. Phys., 2018, 123, 185103. [4] X. Mao and T. C. Lubensky, Annu. Rev. Condens. Matter Phys., 2018, 9, 413. [5] S. C. Glotzer and M. J. Solomon, Nat. Mater., 2007, 6, 557. [6] W. B. Rogers, W. M. Shih and V. N. Manoharan, Nat. Rev. Mater., 2016, 1, 16008. [7] T. Hueckel, G. M. Hocky and S. Sacanna, Nat. Rev. Mater., 2021, 6, 1053. [8] D. Morphew, J. Shaw, C. Avins and D. Chakrabarti, ACS Nano, 2018, 12, 2355. [9] A. B. Rao, J. Shaw, A. Neophytou, D. Morphew, F. Sciortino, R. L. Johnston and D. Chakrabarti, ACS Nano, 2020, 14, 5348. [10] A. Neophytou, V. N. Manoharan and D. Chakrabarti, ACS Nano, 2021, 15, 2668. [11] A. Neophytou, D. Chakrabarti and F. Sciortino, Proc. Natl. Acad. Sci. USA, 2021, 118, e2109776118. [12] W. Flavell, A. Neophytou, A. Demetriadou, T. Albrecht and D. Chakrabarti, Adv. Mater., 2023, 35, 2211197. [13] A. Neophytou, D. Chakrabarti and F. Sciortino, Nat. Phys., 2022, 18, 1248. [14] P. H. Poole, F. Sciortino, U. Essmann and H. E. Stanley, Nature, 1992, 360, 324. [15] A. Neophytou, F. W. Starr, D Chakrabarti and F. Sciortino, Proc. Natl. Acad. Sci. USA, 2024, 121, e2406890121. |