Capillary Force Driving Directional 1D Assembly of Patchy Colloidal Discs

Self-assembly from individual colloidal building units to complex superstructures provides a simple yet effective way for the fabrication of functional materials. A rational design of the unit interactions is essential for it to proceed in a desired manner. Here we show that nondirectional capillary force can be used for directional one-dimensional (1D) assembly of colloidal discs having a designed patch distribution, and colloidal discs with two liquid patches can assemble into long colloidal chains where the stacked colloidal discs have a well-matched configuration with parallel orientation. The length of the chains can be controlled by controlling the experimental parameters. We also found when liquid patches gradually turn into sticky patches, hydrophobic attraction comes into play and becomes dominant, which can also result in chains with continuously increasing length. This method opens an effective avenue for obtaining colloidal chains (or fibers), which can be adapted for the fabrication of other superstructures.