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Directed self-assembly into low-density colloidal liquid crystal phasesYongxiang Gao, Flavio Romano, Roel P.A. Dullens, Jonathan P.K. Doye and Dirk G.A.L. AartsPhys. Rev. Materials 2, 015601 (2018)AbstractAlignment of anisometric particles into liquid crystals (LCs) often results from an entropic competition between their rotational and translational degrees of freedom at dense packings. Here we show that by selectively functionalizing the heads of colloidal rods with magnetic nanoparticles, this tendency can be broken to direct the particles into novel, low-density LC phases. Under an external magnetic field, the magnetic heads line up in columns whereas the non-magnetic tails point out randomly in a plane perpendicular to the columns, forming bottle-brush-like objects; laterally, the bottle-brushes are entropically stabilised against coalescence. Experiments and simulations show that upon increasing the particle density the system goes from a dilute gas to a dense 2D liquid of bottle-brushes with a density well below the zero-field nematic phase. Our findings offer a new strategy for self-assembly into 3D open phases that may find applications in switchable photonics, filtration and light-weight materials.The full paper is available from Physical Review Materials. |