Colloidal Materials

How surface charge changes assembly

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Science  13 Mar 2015:
Vol. 347, Issue 6227, pp. 1214
DOI: 10.1126/science.347.6227.1214-f

The surfaces of colloidal particles can be made asymmetric, such as Janus particles, which can have both hydrophobic and hydrophilic faces. Recently, a method has been developed that can symmetrically decorate a polystyrene colloidal particle with two, three, or four patches bearing charged sulfonate groups. Song et al. show that these particles can pack into unanticipated structures under the influence of an alternating current electric field. Two-patch particles formed multilayers with lower symmetry than the close-packed face-centered cubic packing of uncharged colloids. Three-patch particles formed low-symmetry chains that could pair to create double-helix sections with higher symmetry.

J. Am. Chem. Soc. 10.1021/ja5127903 (2015).

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