Novel kinetic trapping in charged colloidal clusters due to self-induced surface charge organization

Abstract

Colloidal clusters are an unusual state of matter where tunable interactions enable a sufficient reduction in their degrees of freedom that their energy landscapes can become tractable — they form a playground for statistical mechanics and promise unprecedented control of structure on the submicron lengthscale. We study colloidal clusters in a system where a short-ranged polymer-induced attraction drives clustering, while a weak, long-ranged electrostatic repulsion prevents extensive aggregation. We compare experimental yields of cluster structures with theory which assumes simple addition of competing isotropic interactions between the colloids. Here we show that for clusters of size 4 ≤ m ≤ 7, the yield of minimum energy clusters is much less than expected. We attribute this to an anisotropic self-organized surface charge distribution which leads to unexpected kinetic trapping. We introduce a model for the coupling between counterions and binding sites on the colloid surface with which we interpret our findings.

Hunting mermaids in real space: known knowns, known unknowns and unknown unknowns

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The non-classical nucleation of crystals: microscopic mechanisms and applications to molecular crystals, ice and calcium carbonate

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Identification of structure in condensed matter with the topological cluster classification

“…33 Here we describe a recent addition to the collection of high-order structural detection algorithms, the topological cluster classification (TCC) algorithm. This algorithm has been used to investigate higher-order structure in colloidal 32,34 and molecular 35 gels, colloid-polymer mixtures, 36 colloidal clusters, [37][38][39] simple liquids, 60 liquidvapor interfaces, 40 supercooled liquids, [41][42][43] and crystallising fluids. 44 The method shares some characteristics with other topological methods (e.g., the VFA and CNA methods).…”