Collaborative Research: Dual-droplet Electrohydrodynamic Printing of 2D Nanosheets

合作研究：二维纳米片的双液滴电流体动力打印

• 批准号: 1634938
• 负责人: Hong Zhao
• 金额: $ 5万
• 依托单位: Virginia Commonwealth University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-10-01 至 2018-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1634938&HistoricalAwards=false
• 关键词: Collaborative; Research; Dual; droplet; Electrohydrodynamic

Atomically thin, 2D nanosheets are promising components for next-generation electronics. However, there is a lack of scalable manufacturing processes to fully showcase the superior properties of nanosheet materials. Specifically, no currently available technique has the requisite placement accuracy and topology control to build aligned stacks of unwrinkled nanosheets. This award supports fundamental research on a novel dual-droplet electrohydrodynamic printing process. Research results can enable the development of a unique additive manufacturing platform for patterning nanosheets, as well as other anisotropic colloidal particles (e.g., nanowires, and quantum dots). Such technology is crucial for the US to stay competitive in manufacturing and bring forth novel applications of nanosheets in high-performance printed electronics, sensors, actuators, and energy devices. The new dual-droplet electrohydrodynamic printing process involves first depositing a support droplet which acts as a Langmuir-Blodgett trough, followed by a wetting droplet containing colloidal 2D nanosheets. Assembly of the 2D nanosheets will occur as the support droplet evaporates. The research objectives are (1) to understand the effects of solvent surface tensionand volume ratio of the support and wetting droplets on the spreading of the wetting droplet over the support droplet; (2) to understand the effects of nanosheet size and concentration, and substrate wetting properties on the alignment of nanosheets; and (3) to establish the structure-property relationships of the deposited nanosheets. Graphene and Molybdenum disulfide nanosheets will be used in this study. To achieve the first objective, the dual-droplet printing experiments will be conducted. Solvent surface tension will be varied between 30-50 mN/m by changing solvent composition, and volume ratio will be varied from 1 to 100 by changing the driving voltage and pulse width for both support and wetting droplets. The temporal change of spreading area will be measured by high-speed photography with a few tens of microseconds resolution. The second objective will be achieved by both experimental study and computer simulation. For dual-droplet printing experiments, nanosheet size will be varied between 0.2-10 µm in mean diameter, nanosheet concentration in the wetting droplet between 0.01-1 mg/mL, and the receding contact angle of the support droplet will be varied from about 0° with a pinned contact line up to ~90° with a depinned contact line. The nanosheet alignment in the assembly will be analyzed by microscopy characterization. A model of Lagrangian particle tracking will be created for prediction of nanosheet alignment, where molecular dynamics simulation will compute nanosheet dynamics under the evaporation-induced flow. Simulation predictions will be verified by experimental results in terms of nanosheet orientation and alignment. To achieve the third objective, the structure (in terms of topological roughness, sheet-to-sheet alignment, gaps or overlaps between nanosheets) of the deposited nanosheet assembly will be measured using electron microscopy and atomic force microscopy, and the property (conductivity) will be measured using four-point probe.

原子薄的2D纳米薄片是下一代电子产品的很有前途的元件。然而，目前还缺乏可扩展的制造工艺来充分展示纳米片材的优越性能。具体地说，目前还没有可用的技术具有必要的放置精度和拓扑控制来构建未起皱的纳米片的对准堆叠。该奖项支持一种新型双液滴电液动力印刷工艺的基础研究。研究结果可以开发一种独特的添加剂制造平台，用于图案化纳米片材以及其他各向异性胶体粒子(例如纳米线和量子点)。这种技术对于美国保持制造业的竞争力并在高性能印刷电子产品、传感器、致动器和能源设备中带来新的应用至关重要。新的双液滴电液动力印刷工艺包括首先沉积作为朗缪尔-布洛杰特槽的支撑液滴，然后是含有胶体2D纳米片的润湿液滴。随着载体液滴的蒸发，2D纳米片的组装将发生。研究的目的是(1)了解溶剂表面张力以及载体和润湿液滴的体积比对润湿液滴在载体液滴上扩散的影响；(2)了解纳米片的尺寸和浓度以及衬底润湿性质对纳米片取向的影响；(3)建立沉积纳米片的结构-性质关系。本研究将使用石墨烯和二硫化钼纳米片。为了实现第一个目标，将进行双液滴打印实验。通过改变溶剂组成，溶剂表面张力在30~50mN/m之间变化，通过改变支撑液滴和润湿液滴的驱动电压和脉冲宽度，体积比从1到100变化。用几十微秒分辨率的高速摄影测量铺展面积的时间变化。第二个目标将通过实验研究和计算机模拟来实现。在双液滴印刷实验中，纳米片的平均直径在0.2-10微米之间，湿润液滴中的纳米片浓度在0.01-1 mg/mL之间，支撑液滴的后退接触角将从大约0°与钉扎接触线变化到~90°与脱钉接触线。组装中的纳米片状排列将通过显微镜表征进行分析。我们将建立一个拉格朗日粒子跟踪模型来预测纳米薄片的取向，其中分子动力学模拟将计算蒸发诱导流动下的纳米薄片动力学。在纳米片层取向和取向方面，模拟预测将得到实验结果的验证。为了实现第三个目标，将使用电子显微镜和原子力显微镜测量沉积的纳米片组件的结构(根据拓扑粗糙度、片间排列、纳米片之间的间隙或重叠)，并使用四点探针测量性质(电导率)。

项目成果

Interfacial Self-Assembly of Colloidal Nanoparticles in Dual-Droplet Inkjet Printing

• DOI: 10.1002/admi.201701561
• 发表时间: 2018-05-23
• 期刊: ADVANCED MATERIALS INTERFACES
• 影响因子: 5.4
• 作者: Al-Milaji, Karam Nashwan;Secondo, Ray Richard;Zhao, Hong
• 通讯作者: Zhao, Hong

pH-modulated self-assembly of colloidal nanoparticles in a dual-droplet inkjet printing process

• DOI: 10.1016/j.jcis.2018.06.008
• 发表时间: 2018-11-01
• 期刊: JOURNAL OF COLLOID AND INTERFACE SCIENCE
• 影响因子: 9.9
• 作者: Al-Milaji, Karam Nashwan;Radhakrishnan, Vinod;Zhao, Hong
• 通讯作者: Zhao, Hong