Controlled Molecular Assembly for 3D Nanoprinting

加州大学戴维斯分校的刘刚宇教授得到化学系高分子、超分子和纳米化学(MSN)计划的支持，将三维(3D)打印技术进一步微型化，从目前的最小特征尺寸约0.3微米到小于0.1微米(100纳米)，这是人类头发厚度的一小部分(不到1/10万)。虽然3D打印在宏观和微观尺度上已经相对成熟，但实现纳米特征大小和精度仍然是一个挑战。为了解决这一问题，该项目解决了两个基本问题：(A)如何运送超少量材料；(B)如何以纳米精度将材料运送到设计位置。该项目提出了一种具有新的化学概念的新方法，通过设计将分子组装成3D纳米结构。这种方法可能会让我们更接近于通过控制分子的组装方式来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、纳米设备和传感器、组织工程以及生物化学和生物医学研究。它还提高了纳米级的添加剂制造能力，从而增强了美国3D打印行业的竞争优势。研究生在纳米技术和添加剂制造的前沿接受研究方法方面的培训。刘教授继续她与当地社区学院的长期合作以及她的国际教育和外展活动。推广活动包括暑期研究机会和研讨会，以激发不同组别的学生对高等化学教育的兴趣，并提高人们对3D打印及其社会效益的认识。该项目的重点是通过直接编写包含指定成分的解决方案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连接。前者是一种现有的纳米精度高分辨率成像技术，后者可以被认为是一种超小的针头(开口小到30 nm)。研究小组最近改进了飞升液滴的输送，之前的工作和初步数据已经证明了在微尺度水平上组装的可行性。该项目就是建立在这个基础上的。其目的是将液滴的大小降低到亚阿托勒尔水平。为此，对接触时间、压力和表面疏水性进行了修饰，以减弱分子间和分子-表面相互作用，从而增强组装过程的动力学。与当地社区学院的长期合作继续进行，包括设计的研究项目、暑期研究计划、研讨会和教育活动。这些活动吸引了更多不同类型的学生接受高级化学教育。国际研究和教育活动使团队在原子力显微镜和3D打印研究和开发领域获得了良好的信息和最新进展。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.