Controlled Molecular Assembly for 3D Nanoprinting

加州大学戴维斯分校的刘刚宇教授在化学系大分子、超分子和纳米化学（MSN）项目的支持下，进一步将三维（3D）打印技术从目前的最小特征尺寸约0.3微米缩小到小于0.1微米（100纳米），这是人类头发厚度的极小部分（小于1/100,000）。虽然3D打印在宏观和微观尺度上已经相对成熟，但实现纳米级的特征尺寸和精度仍然是一个挑战。为了解决这个问题，该项目解决了两个基本问题：(a)如何提供超少量的材料；(b)如何以纳米精度将材料输送到设计位置。该项目提出了一种新的方法，采用新的化学概念，通过设计将分子组装成三维纳米结构。这种方法可以通过控制分子的组合方式，使我们更接近于实现受控的物理和化学性质。该项目拓宽了3D打印在不同领域的应用，如纳米技术、纳米器件和传感器、组织工程、生物化学和生物医学研究。它还将增材制造的能力提升到纳米级，从而增强了美国3D打印产业的竞争优势。研究生接受纳米技术和增材制造前沿研究方法的培训。刘教授继续与本地社区学院的长期合作，以及她的国际教育和外展活动。外展活动包括夏季研究机会和研讨会，以激发不同群体的学生对高等化学教育的兴趣，并提高对3D打印及其社会效益的认识。该项目的重点是通过直接写入含有指定成分的溶液来控制聚合物分子的组装。为了实现分子水平的控制，最先进的原子力显微镜与纳米流体输送系统相结合。前者是现有的纳米精度高分辨率成像技术，后者可以认为是超小针头（开口小至30纳米）。研究小组最近改进了飞升液滴的输送，先前的工作和初步数据已经证明了在微观水平上组装的可行性。这个项目建立在这个基础上。其目的是将液滴尺寸减小到亚升水平。为此，通过改变接触时间、压力和表面的疏水性来减弱分子间和分子-表面的相互作用，从而增强组装过程的动力学。与当地社区学院的长期合作将继续进行，包括设计的研究项目、暑期研究项目、研讨会和教育活动。这些活动吸引了更多不同的学生进入高等化学教育。国际研究和教育活动使团队在原子力显微镜和3d打印研究和开发工作领域保持良好的信息和更新。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Professor Gang-Yu Liu of the University of California Davis is supported by the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program of the Division of Chemistry to further miniaturize three-dimensional (3D) printing technology from its current minimum feature size of about 0.3 micrometer to less than 0.1 micrometer (100 nanometer), which is a tiny fraction (less than 1/100,000) of the thickness of a human hair. While 3D printing at the macro- and micro-scale is relatively mature, achieving nanometer feature size and precision is still a challenge. To address this, the project tackles two fundamental issues: (a) how to deliver ultra-small amounts of material; and (b) how to deliver the materials to the designed location with nanometer precision. The project advances a new approach with novel chemistry concepts for the assembly of molecules into 3D nanostructures by design. This approach may bring us closer to achieving controlled physical and chemical properties by controlling how the molecules are put together. This project broadens the application of 3D printing in diverse fields, such as in nanotechnology, nanodevices and sensors, tissue engineering, and in biochemistry and biomedical research. It also boosts the capability of additive manufacturing down to the nanometer scale and consequently enhances the competitive edge of the United States 3D printing industry. Graduate students are trained in research methods at the forefront of nanotechnology and additive manufacturing. Professor Liu continues her long-term collaborations with local community colleges and her international education and outreach activities. The outreach activities include summer research opportunities and seminars to stimulate the interest of a diverse group of students in advanced chemistry education and to increase awareness of 3D printing and its societal benefits.The project focuses on controlling the assembly of polymer molecules by direct writing of solutions containing designated components. To achieve molecular level control, a state-of-the-art atomic force microscope is interfaced with a nanofluidic delivery system. The former is an existing technology for high-resolution imaging with nanometer precision, and the latter can be considered as an ultra-small needle (opening as small as 30 nm). The research team has recently improved the delivery of femtoliter droplets, and prior work and preliminary data have demonstrated the feasibility of assembly at the microscale level. The project builds on this foundation. The aim is to reduce the droplet size down to the sub-attoliter level. Towards this end, contact time, pressure and the hydrophobicity of surfaces are modified to weaken inter-molecular and molecule-surface interactions and consequently enhance the kinetics of the assembly process. Long-term collaborations with local community colleges continue with the designed research project, summer research program, seminar and educational activities. These activities attract a more diverse population of students into advanced chemistry education. International research and education activities keep the team well informed and updated in the field of atomic force microscopy and3D printing research and development efforts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.