Hiding in plain view: Colloidal self-assembly from polydisperse populations

Abstract

We report small-angle x-ray scattering (SAXS) experiments on aqueous dispersions of colloidal silica with a broad monomodal size distribution (polydispersity 18%, size 8 nm). Over a range of volume fractions the silica particles segregate to build first one, then two distinct sets of colloidal crystals. These dispersions thus demonstrate fractional crystallization and multiple-phase (bcc, Laves AB${}_2$, liquid) coexistence. Their remarkable ability to build complex crystal structures from a polydisperse population originates from the intermediate-range nature of interparticle forces, and suggests routes for designing self-assembling colloidal crystals from the bottom-up.

5 pages, 3 figures and 2 tables + supplemental analysis (5 pages, 1 figure, 3 tables)

References in corpus (2)

• Equilibrium phase behavior of polydisperse hard spheres
• Phase diagram of a polydisperse soft-spheres model for liquids and colloids

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