Reconfiguring Self-Assembly of Photoresponsive Hybrid Colloids

The reconfigurable self-assembly of colloidal particles allows the bottom-up creation of adaptive materials, yetsignificant challenges remain. Here, we demonstrate a synthesis of photoresponsive Fe2O3/polysiloxane hybrid colloids that performa dynamically reconfigurable self-assembly. Such self-assembly is due to chemical gradients originating from the decomposition ofH2O2by the Fe2O3component under UV irradiation. The morphology of the self-assembly includes chains andflower-structures,where the chains can be transformedin situintoflower-like structures with decreasing UV intensity. Theflower-structures can befurther switched by applying an external magneticfield, leading to orientationally ordered clusters. This, interestingly, leads to anasymmetrical chemical gradient surrounding the assemblies, and transforms the cluster into a micromotor exhibiting a self-propulsion steerable by the magneticfield. Ourfindings demonstrate a new possibility to control and reconfigure the self-assembly ofcolloids, which offers an important pathway for fabrications of adaptive and smart materials at the microscale.