DMREF: Dynamic Control of 3-D Printed Hierarchical Soft Materials via Computation-Guided Molecular Design

3D打印使人们能够快速制作出形状精确的日常使用物品，从车辆零部件和制造原型等可定制的工程物品，到支架和假肢等患者特定的医疗设备。通过使用计算机编程指令，这项技术目前能够制造出精度为微米的统一物品。3D打印已经是一项革命性的技术，但仍然无法创造出在生物系统中找到的真正先进的材料，这些材料通过改变长度尺度上的结构来适应和改变刺激。例如，变色龙通过在纳米尺度上调整皮肤结构来改变它们的颜色。这项研究试图通过引入新的动态调整材料结构的能力来显著推进3D打印的前沿，这种能力可以精确到纳米级。这种能力将通过设计自组装材料来实现，其中自组装可以通过精确调整打印过程中的应力来控制。这种方法将使变色龙般的皮肤材料能够快速适应颜色。这个跨学科的团队汇集了制作材料、测试这些材料如何流动以及打印这些材料的专业知识。然后将其与先进的分子模拟相结合，以设计和评估能够满足纳米级结构的受控即时打印标准的可能材料。这些新材料将通过适应性地印刷具有潜在应用于伪装、减反射涂层、超材料和显示器的新物品，从而造福社会和美国。这项研究还将包括通过学生指导和对STEM领域中代表性较低的学生的教育推广，培养具有广泛专业知识的学生，横跨化学、工程和物理。这项研究将利用失衡的3D打印过程中的压力来‘拨入’打印结构中的层次结构特征。一类被称为瓶刷嵌段共聚物的候选材料可以形成纳米结构，在外加应力下很容易变形。瓶刷嵌段共聚物具有很大的分子设计空间，是一种很有前途的材料平台。绩效指标将开发和实施筛选方法，以探索这一设计空间，并确定用于分级印刷材料的最佳瓶刷嵌段共聚物。计算机驱动设计的整体方法将结合可扩展的合成、大规模模拟和流变特性来系统地设计聚合物分子，以产生所需的流动诱导纳米结构。这一设计程序将被用于优化3D打印纳米结构材料，最终实现具有不同光子(即颜色)属性的3D打印材料的概念验证。除了这一广泛的目标，这项研究将解决开发新的、可扩展的聚合物化学、驱动自组装和瓶刷嵌段共聚物的流变学方面的基本问题。

3-D printing enables the rapid creation of precisely shaped items for everyday use, from customizable, engineered items such as vehicle parts and manufacturing prototypes, to patient-specific medical devices like stents and prostheses. Through use of computer programmed instructions, this technology is currently capable of making uniform items with micrometer precision. 3-D printing is already a revolutionary technology, but still cannot create the truly advanced materials found in living systems that adapt and transform upon stimulation by altering structures across length scales. For example, chameleons change their color by adjusting their skin structure at nanometer length scales. This research seeks to significantly advance the frontier of 3-D printing by introducing the new on-the-fly dynamic capability of tuning material structures down to the nanoscale. This capability will be achieved by designing self-assembling materials, where the self-assembly can be controlled by precisely adjusting the stresses in the printing process. This approach will enable chameleon-skin-like materials capable of rapid color adaptation to be made. This interdisciplinary team brings together expertise on making materials, testing how these materials flow, and printing these materials. This is then combined with advanced molecular simulation to design and evaluate possible materials capable of meeting the criteria for controlled on-the-fly printing of nano-scale structures. These new materials will benefit society and the U.S. by adaptably printing new items with potential applications in camouflage, antireflection coatings, metamaterials, and displays. The research will also involve the training of students with broad expertise spanning chemistry, engineering, and physics, via both student mentorship and educational outreach to students underrepresented in STEM fields.This research will use the stresses in out-of-equilibrium 3-D printing processes to 'dial-in' hierarchical structural features in printed structures. A class of candidate materials known as bottlebrush block copolymers can form nanometer structures that readily deform under an applied stress. Bottlebrush block copolymers are a promising materials platform because they possess a large molecular design space. The PIs will develop and implement a screening methodology to explore this design space and determine optimal bottlebrush block copolymers for hierarchical printable materials. A holistic approach to computer-driven design will combine scalable synthesis, large-scale simulation, and rheological characterization to systematically design polymer molecules to yield desired, flow-induced nano-structures. This design procedure will be implemented to optimize 3-D printed nanostructured materials 'on-the-fly', culminating in a proof-of-concept of 3-D printed materials with heterogeneous photonic (i.e. color) properties. Along with this broad goal, this research will address fundamental questions in developing new, scalable polymer chemistry, driven self-assembly, and the rheology of bottlebrush block copolymers.