Understand Janus particle assembly assisted by surface active molecules

Janus particles assemble into remarkable superstructures due to different chemistry on the two sides of a single particle. The directional interactions between particles can lead to clusters, chains and stripes, which present new structures and physics of colloidal systems. However, how Janus particles assemble in the presence of surface active molecules has not been systematically studied. On the contrary, most of the previous studies have focused on purified Janus particles in the absence of surface active species. In our experiment, surface active molecules have drastically changed the assembly behavior of Janus particles. Using real time imaging and particle tracking algorithm, we studied the dynamics the Janus particles. We also observed intriguing new crystal structures with highly correlated orientation formed by amphiphilic Janus particles assembled with ionic liquid molecules.