Rapid visualized hydrophobic-force-driving self-assembly towards brilliant photonic crystals

Methods that allow the self-assembly of colloidal nano/micro-particles into controllable structures are highly important in many applications, such as photonics, biosensors and electronic chemicals. However, the complicated procedures, low assembly efficiency and multiscale integration of self-assembly of colloidal particles have become great challenges. Here, we first develop a hydrophobic-force-induced self-assembly (HFSA) method to fabricate homogeneous and binary colloidal microdroplets by the feed of volatile fluorocarbon oil. Specially, both mono-color and dual-color colloidal photonic crystals (CPCs) can be architected via HFSA in an efficient (within 200 s), coffee-ring free and visualized fashion. Additionally, such effective HFSA process is further confirmed by dissipative particle dynamics (DPD) simulations. Moreover, a variety of multi-structural colored CPCs are available by using hydrophobic reagents, combining with the visualized HFSA process. This work presents an easy-to-perform platform for designing orderly structural materials, which will significantly highlight the development of colloidal assembly methodology.