Abstract

Open crystals are sparsely populated periodic structures, which, when composed of colloidal particles, are appealing for their variety of applications, for example, as photonic materials, phononic and mechanical metamaterials, as well as porous media [1-4]. Programming self- assembly of colloidal particles into open crystals has proved a long-standing challenge due both to the mechanical instability and lack of kinetic accessibility that colloidal open crystals typically suffer from. The issue of competing polymorphs adds up to this challenge. In this presentation, I will demonstrate a hierarchical self-assembly scheme for triblock patchy particles, yielding in silico colloidal open crystals via what we call closed clusters, which stop to grow beyond a certain size in the first stage and are thus self-limiting [5,6]. Our designer patchy particles are spherical in shape, having two attractive patches at the poles across a charged middle band – a close variant of those synthesized recently [7]. By employing a variety of computer simulation techniques, I will show that the design space supports different closed clusters (e.g. tetrahedra or octahedra with variable valences) en route to distinct open crystals [5,6]. Our design rules thus open up the prospects of realising a number of colloidal open crystals from designer triblock patchy particles, including, most remarkably, the cubic diamond crystal (see Figure 1), much sough-after for is attractive photonic applications.