The well‐known coffee‐ring effect causes colloidal particles to convectively transport toward the contact line of an inkjet droplet leading to a nonuniform deposition of the colloidal particles. In this work, the self‐assembly of colloidal particles in a dual‐droplet inkjet printing configuration to produce a nearly monolayer closely packed deposition of colloidal particles that exhibits a colorful reflection are demonstrated. By controlling the ink surface tensions and jetting parameters, the wetting droplets (the second droplet) containing colloidal polystyrene (PS) nanoparticles quickly spread over the supporting droplets (the first droplet) upon impact. The well‐ordered deposition is achieved by tuning the solvent composition of the wetting droplets and functionalization of the PS nanoparticles to encourage a network formation among the colloidal particles at the air–droplet interface. The underlying self‐assembly mechanism is insensitive to substrates and can be applied to many other material/substrate combinations. Finally, the origin of the color generation is highlighted, and the potential of the dual‐droplet inkjet printing process is discussed for fabrication of optical devices.

中文翻译：

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双滴喷墨印刷中胶体纳米颗粒的界面自组装

众所周知的咖啡环效应会导致胶体颗粒对流地朝着喷墨液滴的接触线传输，从而导致胶体颗粒的沉积不均匀。在这项工作中，展示了在双液滴喷墨打印配置中胶体颗粒的自组装，以产生几乎单层紧密堆积的胶体颗粒沉积，并呈现出彩色反射。通过控制油墨表面张力和喷射参数，包含胶体聚苯乙烯（PS）纳米颗粒的润湿液滴（第二液滴）在撞击后迅速散布在支撑液滴（第一液滴）上。通过调节润湿液滴的溶剂组成和PS纳米颗粒的功能化，以促进在胶滴颗粒之间形成网状结构，可以在空气-液滴界面处形成有序的沉积。潜在的自组装机制对基材不敏感，可以应用于许多其他材料/基材组合。最后，突出了颜色生成的起源，并讨论了双液滴喷墨打印工艺在光学器件制造中的潜力。