Colloidal Rings by Site-Selective Growth on Patchy Colloidal Disc Templates.

Anisotropic colloidal building blocks are quite attractive as they enable the self-assembly towards new materials with designated hierarchical structures. Although many advances have been achieved in colloidal synthetic methodology, synthesis of colloidal rings with low polydispersity and on a large scale remains a challenge. To address this issue we introduce a new site-selective growth strategy, which relies on using patchy particles. For example, by using patchy discs as templates, silica can selectively be grown on only side surfaces, resulting in formation of silica rings. We demonstrate that shape parameters are tunable and find that these silica rings can be used as secondary template to synthesize other types of rings. This method for synthesizing ring-like colloids provides possibilities for studying their self-assembly and associated phase transitions, and this patchy particles template strategy paves a new route for fabricating other new colloidal particles.