Scalable Capillary-Driven Assembly of Asymmetric Nanoparticles via Inkjet Printing

这笔赠款为研究非对称纳米粒子在喷墨打印胶体悬浮液中的毛细驱动自组装提供了资金，用于可伸缩的纳米制造。用于将溶液处理的功能材料输送到柔性基板上的低成本喷墨打印已经成为电子和光伏产品卷到卷加工的革命性技术。然而，由于众所周知的咖啡污渍效应，目前的技术无法产生纳米尺寸的特征和良好控制的图案。不对称纳米粒子在毛细管驱动的自组装过程中可以打破对称性，并可能在打印过程中提高特征分辨率。Janus纳米粒子(JNPs)是指具有不同表面化学组成的两个区域的胶体粒子，由于取向相关的相互作用，将在本研究中用于促进粒子组装。该项目结合了新的纳米粒子合成、多尺度建模、现场观察和高级表征，将重点放在对JNPs与移动的接触线和远离平衡的气液界面的取向相关相互作用的基本理解上。如果成功，这项研究的结果将带来几项技术进步。使用JNPs作为固体表面活性剂，可以更好地控制JNPs的沉积，以避免喷墨打印结构中常见的咖啡环图案。使用JNP作为可调构建块将导致一大类可动态切换的微型设备和智能表面。拟议的工作将有助于建立从蒸发胶滴和薄膜中获得的基于JNP的油墨的组装和沉积之间的重要关联，以及JNP的设计、油墨配方、加工条件和基材性能。这些知识将潜在地实现环境友好的大面积喷墨打印、喷射沉积和开槽模涂覆工艺，以实现下一代柔性电子产品的高通量生产。该项目将通过Drexel？S REU和RET网站建立令人兴奋的跨学科合作，启用新的课程材料，并通过Drexel？S REU和RET网站直接使本科生研究人员和K-12教师以及女性和代表性不足的少数民族学生受益。

This grant provides funding for the investigation of capillary-driven self-assembly of asymmetric nanoparticles in inkjet printing of colloidal suspensions for scalable nanomanufacturing. Low-cost inkjet printing for the delivery of solution-processed functional materials onto flexible substrates has become a revolutionary technology for roll-to-roll processing of electronics and photovoltaics. However, the current technology is incapable of producing nanosized features and well-controlled patterns due to the well-known coffee-stain effect. Asymmetric nanoparticles can break the symmetry during capillary-driven self-assembly and may lead to improved feature resolution during printing. Janus nanoparticles (JNPs), which refer to colloidal particles with two regions of different surface chemical composition, will be used in this study to facilitate particle assembly due to the orientation-dependent interactions. The project that combines novel nanoparticle synthesis, multiscale modeling, in-situ observation, and advanced characterization will focus on the fundamental understanding of orientation-dependent interactions of JNPs with a moving contact line and a liquid-vapor interface away from equilibrium. If successful, the results of this research will lead to several technology advancements. Using JNPs as solid surfactants, the deposition of JNPs can be better controlled to avoid coffee-ring patterns commonly encountered in inkjet-printed structures. Using JNPs as tunable building blocks will lead to a large class of dynamically switchable micro-devices and smart surfaces. The proposed work will help establish important correlations between the assembly and deposition of JNP-based inks from evaporating colloidal drops and thin films, as well as the JNP design, ink formulations, processing conditions, and substrate properties. Such knowledge will potentially enable environmentally-benign, large-area inkjet printing, spray deposition, and slot-die coating processes for high-throughput production of next generation flexible electronics. This project will build an exciting interdisciplinary collaboration, enable new course materials, and directly benefit undergraduate researchers and K-12 teachers via Drexel?s REU and RET sites, as well as women and under-represented minority students.