Hypothesis

Interfacial self-assembly has been demonstrated as a powerful driving mechanism for creating various nanostructured assemblies. In this work, we employed a dual-droplet printing process and interfacial self-assembly mechanism to produce deposits with controlled assembly structures of colloidal nanoparticles. We hypothesize that pH modulation of the droplet will influence the interfacial self-assembly through the multibody interactions, e.g. particle-particle, particle-interface, and particle-substrate interactions, correspondingly affecting the deposition morphology of the colloidal nanoparticles.

Experiments

During the dual-droplet printing, a wetting droplet, containing colloidal nanoparticles, was jetted over a supporting droplet that contains water only. pH modulation was carried out to the supporting droplet. The self-assembly of two kinds of functionalized polystyrene (PS) nanoparticles (carboxyl-PS and sulfate-PS) was systematically investigated under various pH conditions.

Findings

Depending on the pH level of the supporting droplet, deposits of carboxyl-PS particles ranging from clear ring-like patterns to nearly uniform monolayer depositions have been obtained. On the other hand, the sulfate-PS particles, even at extreme basic and acidic environments, successfully assemble into nearly monolayer depositions. The multibody interactions are discussed. Such findings can be harnessed in manufacturing high-performance optical and electronic devices.

中文翻译：

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双液滴喷墨印刷工艺中胶体纳米粒子的pH调节自组装

假设

界面自组装已被证明是用于创建各种纳米结构组装件的强大驱动机制。在这项工作中，我们采用了双液滴印刷工艺和界面自组装机制，以产生具有可控的胶体纳米颗粒组装结构的沉积物。我们假设液滴的pH调节将通过多体相互作用（例如颗粒-颗粒，颗粒-界面和颗粒-底物相互作用）影响界面自组装，从而相应地影响胶体纳米颗粒的沉积形态。

实验

在双液滴打印过程中，将包含胶体纳米颗粒的润湿液滴喷射到仅包含水的支撑液滴上。对载体液滴进行pH调节。在各种pH条件下，系统地研究了两种功能化的聚苯乙烯（PS）纳米粒子（羧基-PS和硫酸盐-PS）的自组装。

发现

根据载体液滴的pH值，已经获得了羧基-PS颗粒的沉积物，其沉积范围从清晰的环状图案到几乎均匀的单层沉积物。另一方面，即使在极端的碱性和酸性环境下，硫酸盐-PS颗粒也可以成功地组装成几乎单层的沉积物。讨论了多体相互作用。这些发现可用于制造高性能的光学和电子设备。